Due to the significant increase in demand, the contribution of aviation to climate change is expected to grow. Additionally, emissions from road traffic and shipping may also increase depending on changes in mobility and technological advancements. Therefore, it is crucial to develop and implement measures and methods to reduce the anthropogenic climate footprint, including the share of different transport modes. Possible methods to reduce the environmental impact of transport include alternative fuels, such as electricity or hydrogen, and technological advancements, such as after-exhaust treatment systems. Besides these rather technical measures, also operational measures are possible, such as optimized routes.
However, the assessment of the effects of such measures and methods with numerical atmospheric models relies heavily on state-of-the-art emission inventories. It is crucial to provide information on the uncertainties in the emission data to ensure a dependable assessment of air quality and climate effects. This information also contributes to the uncertainties in the representation of physical, chemical, and dynamic processes in atmospheric models.
The objective of this session is to bring together the community involved in the development of transport emissions inventories with the community involved in the use of these inventories. On one hand, the aim is to establish a shared understanding of the different requirements and uncertainties related to emission inventories. On the other hand, particular attention will be given to the latest research on the non-CO2 and air quality effects of transport emissions. Contributions can range from measurement campaigns to modelling results and implementing strategies for reducing the environmental impact of transport.
The non-CO2 effects of aviation on climate have received much attention recently from the aviation industry and European policymakers, and several research consortia are working on the topic. Focus is especially on the non-CO2 effects that are both most uncertain and potentially associated with sizeable radiative forcings compared to aviation CO2: contrail formation, the perturbation of atmospheric chemistry by aviation nitrogen oxides (NOx) emissions, and the interactions between aviation aerosols and clouds.
This talk will present recent insights into understanding and quantifying the radiative forcing of the non-CO2 effects of aviation obtained by the ACACIA and Climaviation research projects. Those projects involve several types of models, including computational fluid dynamics, large eddy simulation, and global climate models, and ground-, aircraft- and satellite-based observations. Key insights are (1) improved understanding of the influence of the near field for contrail formation and evolution, (2) a new estimate of global contrail radiative forcing and its adjustments in the LMDZ climate model, (3) quantification of the benefits and risks of contrail avoidance for a given flight, (4) improved understanding of the response of ozone and methane chemistry to aviation NOx perturbations, (5) new results on aviation aerosol-cirrus interactions.
Together, these results inform mitigation options aimed at reducing the climate impact of aviation non-CO2 effects.
How to cite: Bellouin, N. and the Climaviation and ACACIA projects: Recent insights into the non-CO2 effects of aviation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7589, https://doi.org/10.5194/egusphere-egu26-7589, 2026.
In October 2023, Boeing and NASA conducted a joint flight and ground experiment based out of Paine Field in Everett, Washington. This experiment measured the emissions and contrail properties of a Boeing 737-10 equipped with CFM LEAP-1B engines, utilizing the NASA DC-8 airborne laboratory as a chase aircraft. The experiment measured and evaluated particulate emissions and contrail properties from three fuel types over 11 flights and two ground tests. In-situ flight measurements on the DC-8 were typically conducted at distances ranging from 1 to 20 nautical miles behind and within a vertical range of +/- 100 feet of the altitude of the 737-10 for both contrail and plume sampling. Atmospheric conditions ranged from ice supersaturation for persistent contrails to subsaturated temporary contrails to non-contrail conditions. The fuels tested included low sulfur Jet A, 100% paraffinic sustainable aviation fuel, and local Jet A. Significant efforts were made to minimize fuel mixing to avoid contamination with sulfur and/or aromatics across fuel types.
Here we present preliminary data analyses from both the ground test and in-flight measurements, focusing on the measurements of total particles, non-volatile particles measured after passing through a 350C thermal denuder, and ice particle concentration measured using a Cloud Aerosol Spectrometer (CAS) and contrasting the results for different fuel types. Differences in particulate matter with fuel type were also captured by the NASA high-spectral-resolution lidar (HSRL) High Altitude Lidar Observatory (HALO) Water Vapor differential absorption lidar (DIAL) instrument, which sampled approximately 1,000-5,000 ft above the contrails made by the Boeing 737-10. Challenges of using instruments originally developed for particle measurements in clear air to the more complicated environment of an ice cloud such as a contrail will be discussed.
This presentation will also highlight challenges related to logistics, fuel handling, and sampling in contrails, which highlights the complex interactions between atmospheric chemistry and microphysical processes in cloud formation and ice nucleation. Next steps will encompass future campaign needs, outstanding research questions, and measurement techniques.
How to cite: Miller, R., Baughcum, S., Rahmes, T., Tully, C., Griffin, W., Moore, R., Miake-Lye, R., Voigt, C., Sauer, D., Märkl, R., Dischl, R., Roiger, A., and Dalakos, G.: Preliminary Data Analysis of the 2023 Boeing ecoDemonstrator Explorer SAF Emissions and Contrail Project, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2854, https://doi.org/10.5194/egusphere-egu26-2854, 2026.
Contrail cirrus, ice clouds produced when an airplane passes through cold, supersaturated air, make up over half of the effect of aviation on the global energy balance. In the shortwave spectrum, clouds (including contrails) reflect sunlight, exerting a negative forcing. Meanwhile, in the longwave spectrum, they exert a positive forcing, warming the planet due to their cold emission temperature. Thus, depending on atmospheric conditions, cloud properties, the time of day, and the season, the balance between the negative shortwave and positive longwave effects determines whether contrails cool or warm the planet overall. Furthermore, in the context of global climate modeling, the sign and magnitude of the net contrail radiative forcing can be sensitive to assumptions used in the radiation parameterization. For example, simplifications made to the cloud optical properties and assumptions about how clouds overlap within a model column increase the uncertainty in the calculated forcing. In this work, we examine the radiative forcing of contrails in idealized single-column simulations in order to isolate the effect of these assumptions on the calculated forcing. We compare calculations performed with the radiation parameterization used in the LMDZ climate model to a higher-complexity line-by-line code that serves as a reference calculation. Together these results allow us to identify the radiative transfer parameters and configurations that most strongly affect the magnitude and sign of the net contrail radiative forcing, which we will use to identify modeling priorities for the LMDZ contrail parameterization.
How to cite: Czarnecki, P., Bellouin, N., Boucher, O., and Vignon, E.: Sensitivity of Contrail Radiative Forcing to Radiative Transfer Parameterization, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7179, https://doi.org/10.5194/egusphere-egu26-7179, 2026.
Contrail cirrus contributes an estimated 1-2% of all anthropogenic radiative forcing, but this estimate carries significant uncertainty (~70%). A proposed mitigation strategy involves redirecting aircraft to avoid contrail-producing regions, which requires accurate predictions of atmospheric states. To improve these predictions, direct observations of aircraft forming contrails can validate and constrain atmospheric models. Ground-based cameras bridge the spatial resolution gap left by satellite observations, allowing us to observe contrail formation and attribute contrails to specific flights.
We present first results from a large-scale dataset of flight-attributed contrails observed by the Global Meteor Network (GMN) across two continents over several months. The GMN operates 1,600 calibrated ground-based video cameras in 45 countries which have been modified for 24-hour observations to monitor contrails. Contrails were detected and segmented from camera timelapses using machine learning algorithms, automatically associated with flights from Automatic Dependent Surveillance–Broadcast (ADS-B) flight data (then manually validated), and compared to the CoCiP model predictions.
Our analysis highlights the limitations of current prediction models, which early results suggest stem from insufficient vertical resolution to capture vertically thin ISSRs and a limited number of measurements of humidity in the upper troposphere. While errors in model wind data affect our flight associations, the discrepancy between predicted and observed contrail advection offers a new avenue to quantify this wind error and use the derived measurements to improve associations. Finally, we provide statistics of contrail properties observed by the GMN such as altitude, width, and lifetime.
How to cite: Tracey, E., Busquin, L., Vida, D., Schielicke, L., Schultz, L., Busquin, J., Wang, A., Shum, A., Rana, M., Ndabihayimana, D., Tchatchoua Ngassam, B., and Kapoor, K.: Global Meteor Network: Large Scale Ground-Based Camera Validation of Contrail Model Predictions using Machine Learning, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13947, https://doi.org/10.5194/egusphere-egu26-13947, 2026.
Contrails are ice clouds that form behind aircraft. Collectively, they are estimated to have a warming impact that is comparable to aviation’s accumulated CO2 emissions [1]. Individually, the warming impact of a contrail depends, inter alia, on the apparent emission index of ice crystals (AEIice), which is governed by its formation pathway. Accordingly, contrails form when hot exhaust gases mix with cooler ambient air and the plume exceeds water saturation. Under these conditions, water vapour condenses upon particles that are either exhausted by the aircraft or entrained from the environment. These water (or solution) droplets subsequently freeze to generate (contrail) ice crystals.
For aircraft powered by conventional rich-quench-lean (RQL) combustors, contrails predominantly form via non-volatile particulate matter (nvPM) in the “soot-rich” regime. However, lean-burn combustors reduce nvPM emissions by up to several orders of magnitude relative to RQL combustors, driving engine emissions into the “soot-poor” regime. Here, contrails are thought to form via ambient particles and volatile particulate matter (vPM), the latter generated from condensable gaseous emissions [2], including sulphuric acid and lubrication oil. Moreover, sulphuric acid has also been reported as a source of contrail ice crystals behind RQL combustors, for fuel sulphur content of ~500 ppm [3]. Therefore, global simulations that do not incorporate the role of vPM in contrail formation may underpredict AEIice and hence the warming potential of contrails formed under these conditions.
Recently, a model was developed to estimate AEIice across both the “soot-poor” and “soot-rich” regimes by including the role of vPM [4]. We previously integrated this framework into the contrail cirrus prediction model (CoCiP) and showed that incorporating vPM raises the 2019 global contrail net radiative forcing (RF) by up to 30% [5]. Since then, this work has been extended to better constrain the assumed vPM properties, leveraging outputs from two recent flight campaigns that measured AEIice in the “soot-poor” regime [6]. Here, we provide an updated estimate for the 2019 global contrail net RF and characterize the effects of lubrication oil and sulphuric acid emissions. Additionally, we investigate the contrail mitigation potential via fleetwide adoption of 100% sustainable aviation fuel and low-sulphur Jet A-1.
References
[1] D. S. Lee et al., Atmos. Environ., 2021, DOI: 10.1016/j.atmosenv.2020.117834.
[2] F. Yu, B. Kärcher, and B. E. Anderson, Environ. Sci. Technol., 2024, DOI: 10.1021/acs.est.4c04340.
[3] R. Dischl et al., Commun Earth Environ, 2025, DOI: 10.1038/s43247-025-02951-5.
[4] J. Ponsonby et al., Atmos. Chem. Phys., 2025, DOI: 10.5194/acp-25-18617-2025.
[5] R. Teoh, et al., EGU General Assembly, 2025. DOI: 10.5194/egusphere-egu25-17393.
[6] C. Voigt et al., In Review. DOI: 10.21203/rs.3.rs-6559440/v1.
How to cite: Ponsonby, J., Teoh, R., Voigt, C., Shapiro, M., and E. J. Stettler, M.: An updated global contrail forcing assessment accounting for volatile particulate matter, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17795, https://doi.org/10.5194/egusphere-egu26-17795, 2026.
Understanding the microphysics of contrail formation is crucial for predictive models to be developed and deployed. Reliable model predictions are essential to accurately assess the environmental impact of aviation and to develop strategies to mitigate the effects of aircraft-induced cloudiness. This research aims to enhance our knowledge of the nucleation processes involved in contrail particle formation, by investigating the effect of soot emission levels, as well as the more complex fuel effects. To investigate these effects, we developed an altitude chamber facility dedicated to the study of atmospheric nucleation from ground level up to the stratopause. This facility enables precise control on ambient pressure, temperature, and gas composition. Exhaust gases, including particulates from relevant aviation fuels, are being fed to the chamber, emulating the exhaust stream of a jet engine. Utilizing a suite of advanced laser and optical diagnostic techniques, we characterized water nucleation processes varying soot emission levels and fuel composition, while changing ambient temperature under realistic atmospheric conditions around commercial airliners’ cruise altitudes.
Our experimental results provide compelling evidence for the significant role of soot emissions in the water nucleation process. Specifically, we observe that contrail nucleation is both delayed and less intense at lower soot levels in the exhaust. These findings align with previous research, indicating that contrail nucleation intensity diminishes with soot levels up to a certain threshold, beyond which further reductions in soot do not influence contrail formation. Notably, we do not observe an increase in contrail formation intensity at low soot levels, at all tested temperatures, potentially due to the absence of other species or particles that could offer alternative nucleation pathways. Additionally, our measurements reveal variations in fuel effects that extend beyond the soot-contrail relationship. Differences in soot properties, as well as the levels and types of volatiles emitted during combustion, likely account for the observed behaviors when comparing fuels. Ongoing and upcoming tests aim to evaluate the role of ambient humidity on contrail formation and to consider longer residence times to assess contrail development further downstream.
How to cite: Manin, J. and Kaya Eyice, D.: The impact of soot emissions and fuel composition on contrail microphysics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13857, https://doi.org/10.5194/egusphere-egu26-13857, 2026.
A climate-friendly aviation sector requires the development of new propulsion technologies to replace conventional kerosene-based propulsion. Hydrogen propulsion is regarded as a promising alternative, and we assess its implications for the contrail effect. For hydrogen propulsion, water vapor emissions are higher, and soot particles—serving as condensation nuclei for ice crystal formation—are absent.
Using high-resolution simulations, we analyze contrails from hydrogen propulsion systems (either direct combustion or fuel-cell based) throughout their entire life cycle and compare them with contrails from conventional kerosene combustion.
The formation of H₂ contrails on entrained ambient aerosols is simulated, and the potential role of oil droplets and homogeneous droplet nucleation (HDN) is discussed. Because ambient aerosols are typically less abundant than soot particles in kerosene combustion, H₂ contrails contain fewer ice crystals. However, in unfavorable scenarios, ice crystal formation on oil droplets or via HDN can become the dominant mechanism.
We further analyze the early evolution of contrails in the presence of downward-moving wake vortices (age ≲ 5 min) and their transition into contrail cirrus over several hours.
To evaluate the effect of H₂ propulsion on contrail development, we adjust two key input parameters: the water vapor emission and the initial number of ice crystals (to reflect altered formation processes). We examine how the radiative properties of contrail cirrus change in response to systematic variations in the initial ice crystal number. Our results show that factors such as the initial ice crystal number, ambient temperature, and relative humidity strongly influence the contrail life cycle, whereas the increased water-vapor emissions have only a secondary effect. Contrails with fewer ice crystals are shown to have a substantially reduced radiative impact.
This work contributes to the joint efforts of the German Aerospace Center (DLR) and Airbus to evaluate the climatic impact of H₂ contrails.
How to cite: Unterstrasser, S., Lottermoser, A., Zink, J., Hillenbrand, D., and Thi, W.-F.: High-resolution simulations of contrails from hydrogen combustion and fuel cell propulsion, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19535, https://doi.org/10.5194/egusphere-egu26-19535, 2026.
The transport sector, and particularly aviation, is an important contributor to both climate forcing and local air pollution. While measures to mitigate emissions are advancing, airport-related particulate pollution remains insufficiently characterised, especially regarding ultrafine particles (UFPs), which affect both air quality and human health. Due to their aerodynamic diameter below 0.1 µm, UFPs can penetrate deep into the pulmonary alveoli and enter the bloodstream, where they can trigger oxidative stress, inflammatory responses and other adverse physiological effects (Jonsdottir et al. 2019). Airports are recognised as UFP sources, primarily due to emissions from jet engines and auxiliary power units as well as ground support operations. With the predicted growth of the aviation sector, airport-related UFP emissions are expected to increase.
Previous research has identified jet engine lubrication oils as a distinct class of organic compounds associated with airport-related UFPs (Ungeheuer et al. 2022). These compounds contribute to the local air quality burden and can serve as specific tracer species for aircraft emissions. However, detailed chemical characterisation of these compounds remains difficult, because UFPs are due to their low mass and size hard to detect and are often masked by other organic aerosol components. Currently used approaches are mostly based on offline, filter-based techniques that are labor-intensive and offer only limited temporal resolution.
In this study, we present a novel approach for the real-time detection of JetOil tracers using in-situ Orbitrap mass spectrometry (MS). Measurements were conducted approximately 15 km from Frankfurt International Airport using a dielectric barrier discharge ion source coupled to a high-resolution Orbitrap-MS. The setup was operated in fast polarity-switching mode to simultaneously detect JetOil tracers (positive ionization) as well as possible oxidation products and sulfate (negative ionization). In parallel, a scanning mobility particle sizer (SMPS) measured size-dependent particle number and mass concentrations. Over a period of four weeks in August and September 2025, JetOil tracers were frequently detected in air masses originating from the direction of Frankfurt International Airport, coinciding with the airport’s operating hours. Simultaneously, when JetOils are present an increase in UFP concentrations in the 20–40 nm size range. In contrast, no correlation with particle-phase sulfate was observed, indicating that airport operations are not a significant source of sulfate aerosol mass in an urban environment.
Jonsdottir et al. (2019) Commun. Biol., 2(1), 90.
Ungeheuer et al. (2022) Commun Earth Environ., 3(1), 319.
How to cite: David, J., Ungeheuer, F., and Vogel, A. L.: Real-time chemical characterisation of aviation based ultrafine particle using Orbitrap-MS , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6341, https://doi.org/10.5194/egusphere-egu26-6341, 2026.
Aviation non-CO2 emissions influence atmospheric chemistry and physics mainly through NOx, H2O, aerosols and contrail-induced cirrus cloudiness (CiC). These processes alter Earth's radiation budget and thus near-surface temperatures. Studies report that all aviation emissions together currently warm the climate at approximately three times the rate of that associated with aviation CO2 emissions alone. However, this factor is by no means universal, as the various natures of the different climate effects and in particular the different time scales they act on, make blending the effects into one number not straightforward. Climatologically, the CO2 to non-CO2 climate effect factor ranges between 0.5 and 10.5 as it depends on numerous decisions, including climate metric, time horizon and if pulse or continuous emissions are considered. We here explain the influence of some of these decisions on the calculated climate effect and discuss implications. The factor is additionally associated with large uncertainties and for individual flights, it strongly depends on meteorological conditions and location.
For this study, we first develop traffic scenarios with representative flight missions covering a wide range of flight regions, altitudes, distances and aircraft types to calculate air traffic emissions. To analyse how much the contribution of non-CO2 effects to the total climate impact varies for different trajectory types, climate metrics and time horizons, CO2 and non-CO2 climate effects are calculated for these trajectories using the AirClim model. Moreover, we identify the uncertainties of aviation non-CO2 effects, assess their ranges and derive probability distributions of these uncertainties, in particular with regard to lifetimes, radiative forcing and efficacies. To assess the influence of these input data to the uncertainties, we then conduct Monte Carlo simulations with the uncertainty distributions and analyse the confidence intervals for non-CO2 climate effects to be larger than that of CO2. Further, the relative climate effect differences through mitigation measures are calculated and the risk that a measure leads to unintentional climate warming is estimated. This work shall deepen the understanding of aviation non-CO2 uncertainties and help paving the way for their incorporation in operational application.
How to cite: Eichinger, R., Dahlmann, K., Pletzer, J., Grewe, V., Niklass, M., and Weder, C. M.: On the non-CO2 to CO2 ratio of aviation emissions and associated uncertainties, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10340, https://doi.org/10.5194/egusphere-egu26-10340, 2026.
Decarbonizing the transportation sector is a critical component of global climate change mitigation strategies. Achieving net-zero emissions in aviation remains particularly challenging due to the sector’s heavy reliance on carbon-intensive liquid fuels, as well as the substantial climate forcing from non-CO2 effects such as contrails. In China, the rapid expansion of high-speed rail (HSR) provides a promising alternative to short- and medium-haul flights and has the potential to directly reduce aviation demand. However, the magnitude of its contribution to emission mitigation remains uncertain. In this study, we employ a difference-in-differences approach to quantify the causal impact of HSR introduction on domestic civil aviation in China. We estimate CO2 emissions from both aviation and HSR, and further assess the additional substitution and mitigation potential of HSR under a set of future scenarios. Our results show that, between 2008 and 2019, the introduction of HSR led to a 24% reduction in aviation-related CO2 emissions among city pairs connected by HSR. In 2019, CO2 emissions from civil aviation and HSR were estimated at 87.0 and 17.9 Mt, respectively. Given the existing aviation and HSR networks in 2019, HSR operations could reduce aviation CO₂ emissions by approximately 9.1 Mt (10%). Under enhanced substitution conditions—assuming passengers are willing to extend travel time by up to two hours when switching to HSR, combined with power system decarbonization and full-speed HSR operation—the net mitigation potential increases to 50.6 Mt (48%) for the combined civil aviation and HSR transport system. Our findings demonstrate that HSR expansion can deliver substantial climate benefits by decarbonizing the civil aviation sector. With rising environmental awareness, continued electricity decarbonization, and accelerated HSR development, significantly larger emission reductions can be achieved through intermodal substitution.
How to cite: Liu, J., Hou, Y., An, H., Song, G., Mauzerall, D., Klimont, Z., Zhang, Q., and Zhu, T.: From air to rail: Carbon mitigation through modal shift in China’s intercity transport, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1706, https://doi.org/10.5194/egusphere-egu26-1706, 2026.
A comprehensive understanding of international trade-linked transportation CO2 emissions is essential for achieving net-zero emission goals. However, the current simplified representation of transportation patterns obscures the heterogeneity of these CO2 emissions in international trade and limits the development of targeted decarbonization policies. This study developed an integrated and highly detailed model that incorporated commodity-scale modal shares and shipping carbon intensities for each trade pair, assisted by machine learning and observed voyage signals, respectively. The results indicate that transportation modal shares vary significantly across different scales. In 2021, trade-linked transportation contributed 971 Mt CO2 emissions globally. When attributing CO2 emissions to countries and commodities, the simplification of modal share can lead to significant biases through carbon-intensity weighting. By shifting the focus from end-of-pipe emissions to upstream demand, this study identified a decarbonization potential of 41.6% through optimizing transportation distances. The findings offer valuable insights for designing targeted mitigation policies for international freight transportation.
How to cite: Luo, Z.: Global mapping of disaggregated international trade-linked transportation CO2 emissions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10040, https://doi.org/10.5194/egusphere-egu26-10040, 2026.
Abstract: Rapid motorization has established urban road transportation as a dominant contributor to both carbon dioxide (CO2) and air pollutants. However, the long-term co-evolution and potential for synergistic mitigation of greenhouse gases and air pollutants remain to be further quantified at the high-resolution city-fleet scale. Here, we present a comprehensive, vehicle-fleet-based emission dataset for 338 Chinese cities spanning 1985–2023, quantifying CO2, seven air pollutants (NOx, CO, PM2.5, VOCs, SO2, OC, BC), and specialized organic aerosol precursors (I/S/LVOCs ) with 1 km spatial resolution. Our analysis shows that the relationship between urban carbon emissions and pollutant emissions has undergone a profound transition from early synergistic growth to a subsequent period of divergent decoupling. Driven by the stringent implementation of China I to VI emission standards, the seven pollutants have peaked and entered a sustained decline, achieving reductions of 35.7%–84.2% by 2023 relative to their historical peaks. Conversely, while CO2 emissions have not yet peaked, they have begun to decouple from the exponential growth of the vehicle population (VP). We further reveal that this divergence is driven by unbalanced contributions of key factors: the substantial negative contribution of pollution intensity (pollutant/CO2) has effectively offset the pressures from motorization, whereas carbon intensity (CO2/VP) remained a primary driver of emission growth until 2015. By constructing a carbon-pollution peaking matrix at the city scale, we find that only 6.5% of cities—predominantly megacities—have achieved dual peaking of carbon and pollutants. In contrast, 57.6% of cities exhibit a pollutant-peaked and carbon-plateaued pattern, where the effectiveness of pollutant governance has been overwhelmed by the scale effect of vehicle intensity (VP/GDP), resulting in a temporal inconsistency between air quality improvements and climate targets. We propose that the transition toward synergistic mitigation is achievable as supported by scenario analysis: an integrated policy package combining accelerated vehicle electrification, obsolete vehicle phase-out, and freight structure optimization could achieve a 55.7% reduction in CO2 and a 57.9% reduction in air pollutants. These findings provide a robust evidence base for city-specific governance, highlighting the urgency for regions with inadequate carbon-pollutant synergy to proactively implement vehicle emission reduction strategies through structural transformation to align local air quality efforts with national carbon neutrality goals.
How to cite: Zhu, Y. and Zheng, B.: Four Decades of Road Transport Carbon and Air Pollution emissions across Chinese Cities: Trends, Drivers, and Synergistic Mitigation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4397, https://doi.org/10.5194/egusphere-egu26-4397, 2026.
Various programs, regulations, and technologies targeting emissions from the vehicle fleet on roadways around the world have made significant air quality gains over the past few decades. However, recent monitoring in the San Francisco Bay and surrounding areas by the UC Berkeley Mobile Air Pollution Laboratory (CalMAPLab) has shown that high- emission vehicles (“super-emitters”) are likely now having an outsized impact on total fleet emissions. Fingerprinting and bounding the emission factors for these super-emitters is therefore critical in assessing the overall impact on air toxics from these vehicles. Here we present extensive chemical speciation (VOCs, combustion tracers, GHGs) from on- road and on-highway emissions measurements around the Bay Area performed by the CalMAPLab in 2025. We present and compare the speciated fingerprints for vehicles powered by gasoline and diesel, and super-emitters in these classes.
How to cite: Giordano, M. R., Cliff, S. J., Byrne, H. M., Goldstein, A. H., and Apte, J. S.: Super-Emitters On California Roads -On-road VOC fingerprinting from Mobile Monitoring, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8657, https://doi.org/10.5194/egusphere-egu26-8657, 2026.
The expansion of maritime trade has made ship emissions a significant target for SO2 reduction policies. However, there is still a lack of observational data to reflect the long-term changes in SO2 emission from ships. This study conducted continuous observational experiments using Differential Optical Absorption Spectroscopy (DOAS) from 2018 to 2023 in a shipping channel in Shanghai, China. By employing machine learning for gap filling and meteorological normalization, the trends of ambient SO2 related to ship emissions over the six-year period were revealed. Furthermore, whether ships in the channel were using low-sulfur fuels was determined by a decomposition of SO2-rich plumes signals (which reflect high-emission ships) and baseline variations. The findings indicate that ship activities increased ambient SO2 concentrations in the channel by 0.48 ± 0.25 ppbv (43.24% of urban background levels). During the policy adjustment phase (2018 to 2020), Ship related SO2 levels declined steadily due to low-sulfur fuel regulations. While from 2021 to 2023 (the policy stabilization phase), increased ship activity became the dominant driver of rising ship related SO2 levels. Despite policy effectiveness, excessive emissions from cargo ships persisted throughout the study period, suggesting that the emission inventory could be overestimating the actual abatement effectiveness of the policy. This study quantified the contribution of ship emissions to ambient SO2 during 2018–2023 based on observations, evaluating the effectiveness of low-sulfur policies and supporting ongoing efforts to mitigate SO2 pollution from maritime activities. The methodology developed here can be adapted to other global shipping channels, providing a framework for monitoring and regulating ship emissions worldwide.
How to cite: Liu, J., Wang, S., Zhang, Y., Wenig, M., Ye, S., and Zhou, B.: Six-year DOAS observations reveal post-2020 rebound of ship SO2 emissions in a Shanghai port despite low-sulfur fuel policies, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3154, https://doi.org/10.5194/egusphere-egu26-3154, 2026.
Aerosols originate from diverse sources, which determine their physical, chemical and optical properties, and influence both climate and clouds. Fine submicron particles are particularly hazardous; mostly linked to air pollution, they can penetrate deep into the human respiratory system and bloodstream, posing a significant health risk.
The AERO-HDF airborne campaign was conducted in July 2023 over the North of France, the English Channel, and the North Sea; a region characterized by dense shipping traffic. During the mission, a series of scientific flights utilized in situ instruments onboard the SAFIRE (Service des Avions Français Instrumentés pour la Recherche en Environnement) ATR 42 research aircraft to measure the size and optical properties of atmospheric particles using the AVIRAD sampling system, as well as gas concentrations. Additionally, remote sensing data were collected for the same air masses using OSIRIS (Observation System Including Polarisation in the Solar Infrared Spectrum), the airborne simulator for newly launched spaceborne 3MI (Multi-viewing Multi-channel Multi-polarisation Imager) satellite sensor. Atmospheric particles were also sampled to study their chemical composition, morphology and mixing state.
First, our measurements reveal that, in the marine boundary layer, aerosols displayed significant light absorption. They were predominantly externally mixed, and characterised by a dominant mode of particles below 100 nm in diameter and a fine mode mostly consisting in organic aerosols. Multiple passes at very low altitude measured an aerosol Single Scattering Albedo (SSA) of 0.85-0.80 at 630 nm in a fresh ship plume, significantly lower than in the background air (SSA=0.90). These fresh emissions were also accompanied by elevated levels of NOx, SO2, and water vapour. Traces of amorphous carbon, a signature profile of diesel ship engines, were also detected.
Finally, a chemical transport model model (WRF-CHIMERE) was used to model aerosols and gases. We will present comparisons between the model results, in situ data, and polarimeter retrievals. Potentially, we will share preliminary findings regarding the impact of these pollutants on cloud formation.
How to cite: Georgeot, A., Formenti, P., Yu, C., Bauville, A., Deboudt, K., Péré, J.-C., Choël, M., Derimian, Y., Chiapello, I., Fontaine, B., Auriol, F., Delegove, C., Loisil, R., Blarel, L., Hioki, S., Riedi, J., Parol, F., Goloub, P., Hu, Q., and Waquet, F. and the LOA team: Air-pollutants linked to shipping emissions observed in the North of France in July 2023 during the Aero-HdF campaign, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10922, https://doi.org/10.5194/egusphere-egu26-10922, 2026.
Here, IMO 2020 Sulfur Cap regulation impacts on air quality were comprehensively investigated over the Aegean and the Eastern Mediterranean by integrating satellite-based SO2 and NO2 retrievals, and shipping route density analysis for the period of 2019–2023. This approach provided insights into how international maritime fuel regulations affect SO2 and NO2 levels, and heavily trafficked seas. TROPOMI SO2 and NO2 retrievals were evaluated over major shipping routes, open sea areas and important ports. The findings demonstrated that IMO 2020 regulation improvements were regionally and seasonally heterogeneous. In the Aegean Sea, satellite data indicated reductions in SO2 levels, particularly during the summer and autumn. Ports such as Canakkale, Izmir and Aliaga exhibited declines in SO2 concentrations confirming the measurable impact of the Sulfur Cap on air quality around the coastal regions. In contrast, the Eastern Mediterranean presented a more complex picture. Certain ports and routes, notably around Mersin, Taşucu, and Iskenderun, exhibited either no change or even increases in SO2 levels during the post-2020 period. At the regional scale, TROPOMI retrievals showed elevated SO2 over high-traffic corridors, including the Suez Canal approaches and Levantine Basin, despite the Sulfur Cap. Several factors may account for this variability, with potential non-compliance and weaker inspection regime with the Sulfur Cap regulation and the growing intensity of maritime traffic in critical transit corridors such as the Suez Canal. All of these impacts can diminish the anticipated reductions in ship-related SO2 emissions, and thereby weaken the overall improvement in regional air quality.
Route-based analysis showed a slowly declining trend emerged along high-intensity corridors when SO2 concentrations were normalized by shipping activity. These decreases, ranging from 14–16% in the Aegean, and approximately 10% in parts of the Eastern Mediterranean, suggested that the regulation achieved per-unit emission reductions, even though absolute SO2 levels did not decline as strongly due to growing shipping traffic volumes. The analysis of NO2 revealed a different regulatory outcome. While localized reductions were evident around ports such as Beirut, Ashdod, Haifa and Souda, broad-area increases were observed in open-sea regions, particularly along the main transit corridors.
In conclusion, IMO 2020 Sulfur Cap has yielded positive, but irregular air quality improvements across the Aegean and the Eastern Mediterranean. The benefits were pronounced in the Aegean Sea and around major Turkish ports, while the Eastern Mediterranean exhibited mixed outcomes shaped by maritime traffic growth and possible regulatory non-compliance. The observed reductions were generally smaller than the expected emission decreases in fuel sulfur content. These findings showed the significant contribution of shipping to regional air pollution and the necessity for stricter control measures, especially on open seas where enforcement is limited. The observed spatial heterogeneity emphasizes the critical role of localized monitoring and regional governance complementing global maritime policies to achieve cleaner air.
Keywords: Eastern Mediterranean; Shipping; IMO Sulfur Cap; SO2; NO2
How to cite: Kaynak, B., Onay, M. G., and Saracoglu, S.: Impact of Sulfur Cap on Pollution Levels over the Aegean and the Eastern Mediterranean, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13222, https://doi.org/10.5194/egusphere-egu26-13222, 2026.
Air quality is a critical factor in both public health and environmental protection, particularly in coastal regions that are heavily influenced by maritime activity. This study quantifies the contribution of shipping emissions to atmospheric pollutant levels in coastal areas along the Gulf of Mexico, an important international trade hub.
The WRF-Chem v4.5.2 model was used with a horizontal resolution of 5x5 km and 38 vertical levels. The MOZART chemistry mechanism was coupled with the MOSAIC aerosol scheme, and the model was run with an hourly temporal resolution. Maritime emissions were derived from Automatic Identification System (AIS) data, while terrestrial emissions were represented using the CAMS inventory. Representative case studies were identified through long-term synoptic analysis based on 30 years using HYSPLIT. This analysis applied frequency and cluster analysis to air mass transport patterns enabled the dominant synoptic transport components over the Gulf of Mexico to be identified: northerly (N), northeasterly (NE), easterly (E), southeasterly (SE) and northwesterly (NW) flows. These collectively represent over 85% of prevailing atmospheric circulation conditions in the region. For each synoptic component, a representative case study was selected consisting of a four-day simulation period, excluding model spin-up time. Two numerical experiments were conducted for each synoptic component: one including ship emissions, and one excluding them while keeping all other emission sources constant.
The model results were evaluated using observations from 116 air quality monitoring stations (AQMS) located no more than 10 km from the coastline. The results show that shipping emissions have a significant impact on coastal air quality, which varies depending on the pollutant. Of the primary pollutants, nitrogen dioxide (NO2) was found to be the most sensitive to maritime emissions. Maximum contributions were found to be 37% under SE flow and 29% under E conditions, reflecting the efficient transport of emissions from major shipping corridors onto land. Sulfur dioxide (SO2) contributions peaked at around 13% under SE flow, highlighting the impact of fuel sulfur content and shipping density. Particulate matter concentrations were also notably affected, with PM10 contributions exceeding 20% under NE and SE regimes, while PM2.5 exhibited maximum increases of around 15% under E transport. For secondary pollutants, ozone (O3) formation showed positive contributions of up to 15% under E flow, highlighting the role of NOX derived from ships in photochemical processes. In contrast, carbon monoxide (CO) had comparatively smaller impacts, with maximum contributions below 9%. While observed concentrations generally remain within air quality limits, the relative contribution of shipping emissions is significant and represents an important emerging pressure on coastal air quality.
These findings demonstrate that maritime emissions significantly influence pollutant levels in the coastal areas of the Gulf of Mexico, particularly under dominant synoptic regimes. The results emphasize the importance of including shipping emissions in regulatory and mitigation strategies and highlight the need to strengthen the regional implementation and enforcement of MARPOL (Annex VI) regulations to protect air quality and public health in coastal environments.
How to cite: Cortez-Huerta, M., Segado-Moreno, L. C., Sosa Echeverría, R., Fuentes García, G., Baldasano, J. M., Montavez, J. P., and Jiménez-Guerrero, P.: Quantifying the impact of maritime AIS-based emissions on Gulf of Mexico coastal air quality using high-resolution modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4027, https://doi.org/10.5194/egusphere-egu26-4027, 2026.
Near-real-time emission inventories are essential for accurate modeling of air quality and climate impacts. While advances in transportation big data have enabled high-resolution emission inventories in various sectors, existing maritime models still face two key limitations. On one hand, ship technical parameters are updated much slower than activity data, leading to uncertainty in emission calculation. On the other hand, maintaining a dynamically updated inventory platform remains challenging. Here, to address these gaps, this study develops a near-real-time global ship emission inventory model with a daily-updated ship technical database and a scrubber-use simulation module. Our model identifies newly added ships from daily Automatic Identification System (AIS) data and predicts their deadweight tonnage and engine power using an XGBoost-based regression model, enabling more accurate emission factor matching. For sulfur-dioxide and particular matter emission calculation, both low-sulfur fuel use and scrubber use are considered as the potential choices of ships. Compared with models with daily-updated technical database, failure to supplement newly-identified ships results in an underestimation of approximately 12.9% to 16.1% in daily ship emissions. Results from our improved model show that from 2022 to 2024, global annual ship emissions experienced steady growth from 835 million tons to 872 million tons, consistent with the increase in maritime trade. The model also captured the abrupt decline by 40% in daily emissions in the Red Sea following the Red Sea crisis in December 2023, alongside the corresponding rise in the Indian Ocean and South Atlantic Ocean due to rerouted container ships.
How to cite: Zhang, W. and Liu, H.: A near-real-time global ship emission inventory model with daily-updated technical database, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13088, https://doi.org/10.5194/egusphere-egu26-13088, 2026.
Wind-Assisted Propulsion Systems (WAPS) are increasingly recognized as a promising means of exploiting the abundant wind resource, particularly given the high cost and limited availability of renewable fuels. WAPS can contribute significantly to the decarbonization of the shipping sector. Contemporary systems are tightly integrated with onboard energy systems to meet stringent supply chain requirements, with recent developments focusing on larger sail configurations and the integration of hydro-generators to enhance overall efficiency.
Unlike conventionally powered ships, which typically search for the shortest navigational safe route at nearly constant speed, wind-assisted vessels benefit from a more flexible operational paradigm in which routing and speed adaptation are key to realizing their full potential. In the present study, the benefit of jointly optimizing route and speed for a cargo vessel equipped with WAPS is demonstrated. A four-degree-of-freedom steady state simulation model is employed to evaluate vessel performance under varying environmental conditions based on ERA5 data. To identify energy-optimal routes between ports, a dedicated algorithm is developed and presented that combines probabilistic roadmap techniques with dynamic programming.
The proposed framework is highly flexible with respect to the integration of diverse meteorological datasets and ship performance models. A key novelty is its ability to accommodate negative power and energy values, thereby enabling the optimal recuperation of energy through hydro-generator operation. The results indicate a substantial reduction in energy consumption through the combined optimization of routing and speed adjustment across multiple transport routes over a one-year operational period Moreover, by avoiding harsh weather conditions, routing enabled numerous routes that would have been unviable without it. The case study demonstrated average energy savings of approximately 75%, and up to 100% for selected low-speed trans-Atlantic crossings.
How to cite: Schwedt, T., Gosala, D., Lampe, T., Fitz, A., Teske, T., Stutz, S., Schmitz, L., Gosala, V., Klein, M., and Ehlers, S.: Joint Optimization of Route and Speed for Energy-Efficient Wind-Assisted Shipping, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19969, https://doi.org/10.5194/egusphere-egu26-19969, 2026.
Aviation emissions at typical cruise altitude (~9-13 km) consists of a blend of chemical components including aerosols and their precursor gases, affecting the Earth's radiation budget via both direct and indirect aerosol effects, resulting in a significant climate effect. Current estimates of aviation-induced climate effects are based on coarse-resolution global aerosol-climate models, which are not able to resolve the microphysical processes at the aircraft plume scale. This results in large uncertainties in the aviation-induced impact on aerosol number and size, which are key quantities for estimating the aerosol indirect effect, especially for low-level liquid-phase clouds. A double-box aircraft exhaust plume model is developed to explicitly simulate the aerosol microphysics inside the dispersing aircraft exhaust plume, together with a simplified representation of the vortex regime (which begins ∼ 10 s after emission and captures the dynamics of aerosol particle interactions with contrail ice particles). This study focuses specifically on sulfate (SO4) and soot aerosols, as well as the total number concentration of aviation-induced aerosol particles. The plume model is used to quantify aviation-induced aerosol number concentrations at the end of the dispersion regime where the exhaust has dispersed on scales resolved by global models (~46 h), and the results are compared with those from the instantaneous dispersion approach commonly used in global models. The difference between the two approaches is defined as the plume correction. For typical North Atlantic cruise conditions, the plume correction ranges from −15% (with contrail ice in the vortex regime) to −4.2% (without contrail ice). A tendency-based process analysis shows that the negative value of the plume correction is due to the higher efficiency of coagulation process in the plume approach, leading to lower total particle number concentrations compared to the instantaneous dispersion approach. Sensitivity studies performed for different world regions highlight the role of background conditions for the plume-scale processes, with the plume correction varying between −12 % for Europe and −42 % for China. Parametric studies performed on various aviation emission parameters used to initialise the plume model demonstrate the strong influence of contrail ice in the vortex regime, which substantially reduces aerosol number concentrations in the plume approach. They also show a large sensitivity towards aviation fuel sulfur content, as SO2 emissions and subsequent H2SO4 formation are key drivers of nucleation. The plume model can be directly implemented in coarse-resolution global aerosol–climate models or used as offline parametrisation to constrain quantifications of the climate effects of aviation-induced aerosol particles.
How to cite: Sharma, M., Righi, M., Hendricks, J., Schmidt, A., Sauer, D., and Grewe, V.: A double-box model for aircraft exhaust plumes based on the MADE3 aerosol microphysics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2272, https://doi.org/10.5194/egusphere-egu26-2272, 2026.
Despite the ongoing climate crisis and recent pandemic-induced disruption, the aviation sector is expected to experience 5% annual growth over the next decade. While the industry moves towards decarbonisation through use of sustainable fuels and improved operating practices, the contribution by non-CO2 effects become ever more apparent. Contrails and contrail-induced cirrus clouds contribute an estimated 57% to the sector’s total effective radiative forcing (ERF). Contrail avoidance methods are gaining ground as tools to strategically reroute flights to reduce their ERF by predicting contrail forming regions in advance.
The task of prediction remains a challenge however, with typical methodologies employing either highly parametrised models that suffer from uncertainties, or machine learning methods that are heavily abstracted away from the background physics. We propose a novel, robust method for contrail prediction that leverages large-scale population behaviours. Using ERA-5 reanalysis and the OpenContrails dataset for over 50,000 confirmed contrails between 2019 and 2020 over North America, we train an informed contrail predictor using Bayesian methods which we verify on unseen data. We will present the results and statistical evaluation of this model, which we believe provides a scalable but interpretable contrail predictor that could be run using output from numerical weather prediction models.
How to cite: Williams, D., Morcrette, C., and Haywood, J.: Predicting Aviation Contrail Occurrence Using Bayesian Population Statistics From Reanalysis Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3555, https://doi.org/10.5194/egusphere-egu26-3555, 2026.
The impact of aviation soot on natural cirrus clouds is considered the most uncertain among the climate impacts of the aviation sector. In this study, a global aerosol-climate model equipped with a cirrus parametrisation is applied to quantify the impact of aviation soot on natural cirrus clouds and its resulting climate effect. For the first time, the cirrus parametrisation in the model is driven by novel laboratory measurements specifically targeting the ice nucleation ability of aviation soot, thus enabling an experimentally-constrained estimate of the aviation-soot cirrus effect. The results indicate no statistically significant impact of aviation soot on natural cirrus clouds, with an effective radiative forcing of −6.9 ± 29.8 mW m−2 (95% confidence interval). Sensitivity simulations conducted to investigate the role of other ice nucleating particles (INPs) competing with aviation soot for ice supersaturation in the cirrus regime (soot from sources other than aviation, mineral dust and ammonium sulphate) further show that the impact of aviation soot remains statistically insignificant also when the impact of these other INPs on cirrus is reduced in the model. Acknowledging that the complexity of the soot cirrus interaction is associated with uncertainties, the model results supported by dedicated laboratory measurements suggest that the climate impact due to the aviation soot cirrus effect is likely negligible with no statistical significance.
How to cite: Righi, M., Testa, B., Beer, C. G., Hendricks, J., and Kanji, Z. A.: Aviation soot interactions with natural cirrus clouds are unlikely to have a significant impact on global climate, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4926, https://doi.org/10.5194/egusphere-egu26-4926, 2026.
The climate impacts of aviation arise in 3 main ways. Carbon dioxide is the inevitable consequence of burning hydrocarbon fuels. Nitrogen oxides (NOx) are formed by the high temperatures in jet engines and subsequently affect the concentrations of the greenhouse gases ozone and methane. Contrails and cirrus are produced following the emission of a range of particle precursors under certain atmospheric conditions. Roughly, contrail-cirrus is responsible for half of the overall climate impact of aviation, NOx for a sixth, and CO2 the remaining third. Significant climate wins would result from reducing NOx and contrail-cirrus, the non-CO2 impacts from aviation.
The UK government has established a £30M research programme on Aviation’s non-CO2 Impacts on the Climate which covers atmospheric and technological projects involving academia and industry and funded through Natural Environment Research Council (NERC) and the Aerospace Technology Institute (ATI). In this way it links the climate science and technology research. The programme focuses on (a) improving our understanding of aviation’s non-CO2 impacts; and (b) identifying and developing mitigating actions to address those impacts.
The research programme brings together atmospheric scientists, technologists, industry partners and policymakers to research into how NOx emissions, contrails and other non-CO₂ effects influence climate, as well as into realistic mitigation options. The coordination team provides strategic direction, integrates findings to offer higher-level insights, and facilitates engagement with government (especially Department for Transport and Department for Business & Trade), industry, NGOs and international experts. Activities include workshops, annual meetings, cross-project synthesis and policy-facing assessments. The project aims to deliver evidence that informs operational, technological and regulatory decisions, supporting the UK’s transition to lower-impact aviation
This presentation describes the projects covered in the proposals, their achieved and intended key learnings and how research in the various projects will be used to provide actionable outcomes. Opportunities for collaboration with international partners will be discussed.
How to cite: Harris, N., Smallwood, A., Westwood, M., and Cui, X.: UK research programme on aviation’s non-CO2 impacts on the climate , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5636, https://doi.org/10.5194/egusphere-egu26-5636, 2026.
Contrails are a major contributor to aviation’s non-CO₂ climate effects, and trajectory-based mitigation concepts depend on robust estimates of contrail formation, persistence, optical properties, and radiative forcing. In EMAC, contrails evolve along Lagrangian trajectories and are subsequently transformed back to grid-point space to derive contrail climate change functions (CCFs; Frömming et al., 2021). However, the baseline EMAC contrail scheme has previously shown very low optical thickness values, which can be linked to low humidity values and to artefacts introduced by sampling and mapping between the Lagrangian and Eulerian frameworks.
We present targeted developments of the EMAC contrail submodel that address (i) humidity and saturation consistency and (ii) trajectory–grid coupling. First, we revise the humidity formulation by introducing an H₂O compensation factor and an explicit humidity threshold for contrail processes, implemented with a consistent treatment of saturation specific humidity and timestep handling. Second, we extend the grid-point-to-Lagrangian mapping by adding four-point bilinear horizontal interpolation of meteorological variables at the exact Lagrangian positions, reducing step-like gradients when trajectories cross grid boxes. Third, we update the Lagrangian-to-grid transformation to mitigate mapping artefacts affecting contrail ice water content and optical properties. In addition to the previously investigated North Atlantic flight region, we also analyse contrail climate change function fields for multiple days over Asia.
In the shown test cases, the added humidity threshold systematically reduces contrail persistence: the baseline setup (no threshold) yields a characteristic lifetime of ~7.8 h, while threshold-based setups reduce lifetimes to ~4.0–4.2 h and down to ~2.9–3.5 h depending on threshold strength. These developments improve numerical consistency and reduce sampling/mapping artefacts, providing a more robust basis for EMAC-based contrail RF estimates and for constructing contrail climate change functions for aviation applications.
The project leading to this study was funded by the European SESAR programme under Grant Agreement No. 101114785 (CONCERTO). High performance supercomputing resources were used from the DKRZ Cluster in Hamburg.
References:
[1] Matthes, S., Lührs, B., Dahlmann, K., Grewe, V., Linke, F., Yin, F., Klingaman, E. and Shine, K. P.: Climate-Optimized Trajectories and Robust Mitigation Potential: Flying ATM4E, Aerospace 7(11), 156, 2020.
[2] Frömming, C., Grewe, V., Brinkop, S., Jöckel, P., Haslerud, A. S., Rosanka, S., Van Manen, J., and Matthes, S.: Influence of weather situation on non-CO2 aviation climate effects: The REACT4C climate change functions, ACP, 21, 9151 – 9172, 2021.
How to cite: Peter, P., Matthes, S., Frömming, C., Jöckel, P., Dietmüller, S., and Grewe, V.: Improved humidity treatment and trajectory–grid mapping in the EMAC contrail submodel and their implications for contrail climate change functions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5744, https://doi.org/10.5194/egusphere-egu26-5744, 2026.
One of aviation's largest non-CO2 climate impacts originates from persistent contrails. Since only a small minority of flights cause persistent contrails, preventing contrail formation has potential to be cost-effective in comparison to other measures and therefore could be part of climate change mitigation strategies in the transport sector. However, determining which flights cause persistent contrails to form is uncertain, as is the overall extent of the impact of contrails on climate change. More research is needed in both areas to fully understand and mitigate these uncertainties.
Observations of persistent contrails through geostationary satellite-based imagers can be used to develop non-CO2 climate impact inventories. Recent work has focussed on training machine learning models to detect contrails at large scale. To date, these models have been trained and evaluated on observations from the same satellite instrument. But in order to get global contrail coverage, one must consider multiple instruments mounted on different satellites (e.g., GOES-ABI for the Americas, Meteosat-FCI for Europe and Africa, and Himawari for Asia).
In this work, we analyze whether a deep learning model trained on one satellite instrument can be applied to data from others. Validating this approach is important, as it could eliminate the need to create large labeled datasets for every new instrument which is a time-consuming and expensive process. We also explore if training models on a combined dataset of multiple satellite instruments can lead to overall quality improvement in contrail detection.
How to cite: Michlmayr, E., Ng, J. Y.-H., Kuebler, J., Favia, A., Van, S., Vogler, M., and Geraedts, S.: Towards Global Contrail Observation: From Single-Instrument to Global Geostationary Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7834, https://doi.org/10.5194/egusphere-egu26-7834, 2026.
Preliminary data analyses from the 2023 joint NASA and Boeing ecoDemonstrator campaign indicate that volatile particulate matter (vPM) contributed significantly to the measured ice emissions indices (AEI ice) as non-volatile PM (i.e., soot) emissions were very low for the particular engine studied. Similarly, as the fuel sulfur contents of the two primary fuels tested during the campaign were also very low, it is likely that lubrication oil vented from the engine into the core flow of the exhaust made up a large portion of the vPM; however, there is very little measurement data to verify this claim. Widely available modelling tools are now starting to include simplified vPM activation parameterizations in their contrail ice formation schemes, without the necessary data for evaluation. This may overstate the climate impacts of the simulated contrails, which has broader implications on contrail mitigation strategies.
In this study, the pycontrails model was adapted to include the properties of the fuels used during the ecoDemonstrator campaign. The current vPM activation scheme in the model follows a competition-based, temperature-dependent approach for ice formation, where a constant vPM concentration competes for available water vapor with emitted soot particles (non-volatile PM) and ambient aerosol particles. Temperature values are sourced from meteorological input data to the model that is subject to some uncertainty. To test the temperature sensitivity of the vPM activation scheme on the predicted AEI ice, this study will compare model output between meteorological initializations using ERA5 reanalysis data and similar parameters measured during the 2023 ecoDemonstrator campaign. Comparisons are also made with measured AEI ice values.
This study will provide insights into how simple treatments of particle activation are likely to be highly influenced by the input assumptions of the model. The findings will help to determine future campaign goals that aim to make measurements of vPM more thoroughly as well as identify key sensitivities to test in future contrail modeling intercomparison projects.
How to cite: Tully, C., Baughcum, S., and Miller, R.: The role of volatile particulate matter in simulated contrail AEI ice compared to the Boeing ecoDemonstrator campaign, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2951, https://doi.org/10.5194/egusphere-egu26-2951, 2026.
Contrail cirrus contributes significantly to aviation’s climate warming impact. To limit this impact, flight trajectories can be climate-optimised by minimising both CO2 and non-CO2 emissions. Operationally, safety is often an overriding consideration that must be accounted for before a climate-optimised flight trajectory can be undertaken. Since atmospheric turbulence is the leading cause of commercial aviation accidents, it is vital to establish if and how ice supersaturated regions (ISSRs) are spatially related to region with moderate-or-greater (MOG) turbulence. This link is motivated by the role of vertical air motions, which promote ice supersaturation through adiabatic cooling and are also a defining characteristic of atmospheric turbulence.
Using European Centre for Medium-Range Weather Forecasts ERA5 reanalysis data and the most relevant clear air turbulence (CAT) diagnostics, we first examine whether ISSRs and MOG turbulence occur concurrently and whether they are correlated. Preliminary results indicate a weak relationship exists between the two regions. Analysis of the instantaneous plots indicate that, while co-occurrence is uncommon, the two regions often occur adjacent to each other. This adjacency is particularly evident in three-dimensional reconstructions of regions where an intersection had occurred. We quantified this spatial relationship via the Euclidean distance from an ISSR to a MOG CAT region and aggregated these distances (e.g., mean distance) to identify regions that frequently exhibits this behaviour. Finally, this measure is used to establish whether ISSRs that originate from large scale vertical movements and MOG CAT are related. These insights provide a foundational step toward establishing whether this underlying relationship between the two regions can be leveraged to improve forecast confidence and the implications on the operational complexity of safe, climate-optimised flight trajectories.
How to cite: Wong, H. L., Palacios, R., and Gryspeerdt, E.: Is There a Spatial Link Between Ice Supersaturation and Aviation Turbulence?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13064, https://doi.org/10.5194/egusphere-egu26-13064, 2026.
Aviation’s contribution to climate change stems from both CO2 and non-CO2 emissions. Among the latter, the warming effect generated by contrail-cirrus is recognised as a major contributor, albeit large uncertainties remain (Lee et al. 2021).
A condensation trail - or contrail - is composed of ice crystals which form behind an aircraft at high altitudes in sufficiently cold air. The formation is also influenced by engine technology, operating conditions and the fuel type. On the other hand, contrails are persistent in Ice Super-Saturated Regions (ISSRs) and their transition into contrail-cirrus depends on many atmospheric parameters and also on early contrail properties. ISSRs are local atmospheric air masses characterised by low temperatures and a high humidity level that is saturated versus ice.
In order to reduce aviation’s climate impact, hydrogen propulsion has been considered as one promising alternative, in line with the European Green Deal and Clean Aviation Strategic Research and Innovation Agenda (SRIA). In this context, the EU-funded HYDEA project was launched in 2023.
The advantage of a hydrogen-powered aircraft compared to kerosene is that the former combustion is free of carbon-dioxide emissions as well as soot particles and sulphur oxides, classical pathways to ice formation. However, H2 combustion also produces NOx and approximately 2.6 times more water-vapour than kerosene combustion. In this case, a need for modelling new ice crystal formation pathways is required to understand how ice crystals are formed and what properties they would have in order to ultimately understand their climate impacts.
Consequently in HYDEA WP6, we investigate several aspects of ice crystal formation modelling for a hydrogen-powered engine. Three distinct ice crystal (IC) formation pathways were considered and investigated. On one hand ONERA uses their 3D CFD model, CEDRE, to perform high-fidelity simulations and their box model MOMIE to investigate the potential role of NOx to act as condensation nuclei. On the other hand, DLR uses their Lagrangian Cloud Module (LCM) box model approach to investigate the role of background aerosols and that of lubrication oil on IC formation. However, they need dilution information from an engine exhaust in order to perform such a study.
Several simulations were performed using ANSYS CFX solver by GEAP and FLUSEPA solver by AIRBUS to “feed” DLR’s box model. The use of two distinct solvers allows for an inter-model comparison and their potential impact on the IC formation. The use of the Common Research Model (engine and aircraft) allows comparison of isolated versus installed configurations. Three configurations were considered: an isolated engine, an engine-pylon and a full aircraft configuration. While we limit our simulations to the “jet regime” (approx. 300 m downstream of the exhaust), these configurations should provide insights on their influence on the mixing process in the plume.
References:
Lee, David S., et al. "The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018." Atmospheric environment 244 (2021): 117834.
How to cite: Purseed, J., Mackay, C., Unterstrasser, S., Zink, J., Thi, W.-F., Vannini, F., Roszkiewicz, K., Iglewski, T., Bonne, N., and Terrenoire, E.: HYDEA Project Work Package 6: Contrail formation pathways for hydrogen combustion, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9775, https://doi.org/10.5194/egusphere-egu26-9775, 2026.
Current best estimates suggest that aviation contributes around 5% to global warming, with a substantial fraction arising from non-CO₂ effects. While contrail cirrus dominates these non-CO₂ impacts, aerosol-cloud interactions have also been suggested to play an important role. However, aviation-induced aerosol-cloud interactions remain poorly quantified, limiting our ability to inform future aviation climate mitigation policies. Improving our understanding of aviation-induced aerosol-cloud interactions is therefore essential, particularly in the context of ambitious mitigation targets and emerging alternative fuels.
Here, we quantify the effective radiative forcing (ERF) from aerosol–radiation interactions (ARI) and aerosol-cloud interactions (ACI) driven by aviation emissions using the UK Earth System Model (UKESM). Three-dimensional emissions of H2O, SO2, soot, and NOx are constructed based on fuel consumption data from two independent aviation inventories: the Aviation Environmental Design Tool (AEDT) and the Aviation Integrated Model (AIM), and are implemented within the UKCA chemistry-aerosol framework. Atmospheric chemistry, aerosol microphysical processes, and cloud microphysical processes are simulated with UKCA and its GLOMAP component.
A present-day simulation for 2018 indicates a net aviation aerosol ERF (ARI + ACI, SW + LW) of -24 mW m-2 when using AEDT-based emissions, relative to a control simulation without aviation emissions. This forcing is dominated by ACI (-22 mW m-2), with shortwave and longwave contributions of -17 and -5 mW m-2, respectively, while ARI contributes only -3 mW m-2. Very similar results are obtained using AIM-based emissions, yielding a net ERF of -27 mW m-2. These values are large enough to offset approximately half of the best-estimate ERF from contrail cirrus reported by Lee et al. (2021).
Changes in cloud macrophysical properties such as cloud fractions and liquid water paths remain difficult to detect above internal variability, whereas cloud microphysical responses are clearly visible. Cloud droplet number concentrations in the upper troposphere increase by up to ~15% over northern mid- to high-latitude regions, primarily driven by sulphate-liquid cloud interactions. Interactions between soot and ice clouds, including contrail cirrus, are not yet fully represented and will be addressed in future work by coupling UKESM with more sophisticated cloud microphysics model, CASIM.
Ongoing simulations extend this analysis to 2050 under multiple fuel scenarios, including conventional fuels, sustainable aviation fuel (SAF), and liquid hydrogen. While growing aviation demand amplifies both warming and cooling effects under conventional fuels, reduced aerosol emissions from alternative fuels are expected to weaken aviation-induced aerosol cooling effect. Results from these future scenarios will also be presented.
How to cite: Yoshioka, M., Dray, L., Field, P., Zhang, W., Schafer, A., and Rap, A.: Effective radiative forcing of aviation-induced aerosols in present-day and future climate simulated with UKESM, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13213, https://doi.org/10.5194/egusphere-egu26-13213, 2026.
Contrail cirrus, aviation-induced condensation trails and their associated cloudiness form when ice crystals nucleate on exhaust and ambient aerosols. The size, morphology, and chemical composition of these aerosols influence contrail formation and the resulting atmospheric perturbations, and are controlled by multiple factors, including fuel type and combustion conditions. To investigate these physicochemical effects, emissions from an aircraft Auxiliary Power Unit (APU) were characterised under full-load and ready-to-load operating conditions. Particle size distributions (PSDs) were measured for conventional Jet A-1 and aviation fuel surrogates composed of n-paraffins and iso-paraffins, to assess the influence of fuel composition on emissions. Under full-load conditions, n-paraffin surrogates produced the smallest particles, with a modal diameter of 22 nm, compared with 28 nm and 32 nm for iso-paraffin surrogates and Jet A-1, respectively.
The fractal structure of the emitted particles was examined using a tandem Aerodynamic Aerosol Classifier (AAC) - Scanning Mobility Particle Sizer (SMPS) system and Transmission Electron Microscopy (TEM). In parallel, the ice-nucleating behaviour of APU emissions was investigated using the Portable Ice Nucleation Experiment (PINE) chamber.
The IATA Net Zero Roadmap projects that 62% of aviation-sector CO2 reductions by 2050 will rely on replacing 80-90 % of conventional aviation fuel with sustainable alternatives (IATA, 2023). As higher sustainable aviation fuel (SAF) blend ratios are increasingly adopted, understanding how fuel-dependent emission properties and ice-nucleating behaviour influence contrail formation is essential for assessing the full climate impact of these mitigation strategies.
Reference: IATA: Energy and New Fuels Infrastructure Net Zero Roadmap, International Air Transport Association, https://www.iata.org/en/programs/sustainability/roadmaps/, 2023.
How to cite: Winter, E., Macklin, J., Gamble, G., Ahmed, I., Murray, B., Pourkashanian, M., and Stettler, M.: Characterisation of aircraft APU aerosol emissions relevant to contrail formation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9492, https://doi.org/10.5194/egusphere-egu26-9492, 2026.
Non-CO2 effects from aviation, particularly aerosol-cloud interactions, remain one of the largest uncertainties in the climate impact assessment of the transport sector. A key challenge is how aviation-emitted soot contributes to cirrus formation by acting as a potential ice-nucleating particle (INP). Current estimates span a wide range in both sign and magnitude, largely due to limitations in representing atmospheric ice nucleation and the dynamics governing cirrus formation, as well as the poorly constrained ice-nucleating properties of aviation soot in numerical models.
Here, we present a combined modelling and experimental framework to quantify how aviation soot ice nucleation perturbs cirrus properties and the resulting radiative impacts. We use the Met Office Unified Model (UM) coupled with the two-moment Cloud AeroSol Interaction Microphysics scheme (CASIM), which enables prognostic representation of ice crystal number concentration and explicit simulation of INP-driven perturbations. To represent soot-specific ice nucleation, we implement an active site density parameterisation for soot deposition freezing following Ullrich et al. (2017) within CASIM. In parallel, laboratory measurements are conducted using the Portable Ice Nucleation Experiment (PINE), a cloud expansion chamber, to characterise ice nucleation by aviation-relevant soot under cirrus conditions. The resulting constraints on soot INP efficiency across temperature and ice supersaturation are used to evaluate and refine the model parameterisation. Together, the laboratory constraints and regional simulations provide physically based estimates of aviation soot impacts on cirrus and associated radiative forcing.
The model is run in a regional configuration over Europe, focusing on high-traffic flight corridors and selected meteorological case studies relevant for cirrus formation. Model experiments compare baseline and aviation-perturbed simulations and explore sensitivity to assumptions on soot INP activity and emissions. Aviation soot emissions are prescribed using a new emission inventory developed in this work, built upon the GAIA (Global Aviation emissions Inventory based on ADS-B; Teoh et al., 2024). GAIA provides high-resolution, real-world flight activity and emissions, while our inventory explicitly separates contrail-processed and unprocessed soot particles. This separation captures the potential influence of contrail processing on soot ice-nucleating ability and provides a more comprehensive representation of the soot INP population available for cirrus formation.
How to cite: Qiu, K., Yoshioka, M., Field, P., Macklin, J., Murray, B., Daily, M., and Rap, A.: Constraining the role of soot in ice formation for robust estimates of aviation aerosol-cloud interactions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17802, https://doi.org/10.5194/egusphere-egu26-17802, 2026.
Quantitative assessments of CO2 and non-CO2 climate effects of aviation emissions require the choice of a physical climate metric. In consequence estimating mitigation potentials or integrating non-CO2 effects in legislation or cost-benefit analyses require the choice of a metric. However, since various metrics are currently in use and estimates and numbers vary over different climate metrics, it is desirable and necessary to have conversion factors available which allow to convert from one physical climate metric to another. Hence, we introduce an approach how such climate metric conversion factors can be calculated and present an initial set based on the climate response model AirClim. These conversion factors can be used for various applications. These include, for example, converting results from models that only calculate radiative forcing into a climate metric and scaling model results calculated with different metrics to the same one for one-to-one comparisons.
In addition, the conversion factors can be used for convenient analyses of the influence of metric choice on the results of a climate assessment. To this end, it is shown here how the ratio of non-CO2 to CO2 differs depending on the choice of metric. The metrics GWP, EGWP, GTP and ATR are analysed, each with a time horizon of 20, 50, 100 and 500 years. The choice of the temporal emission curve is also analysed and it is shown exemplarily why a sequence of pulse emissions does not provide the same climate metric result as constant emissions.
How to cite: Dahlmann, K., Matthes, S., Grewe, V., and Eichinger, R.: Role of climate metrics in aviation climate assessments , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20106, https://doi.org/10.5194/egusphere-egu26-20106, 2026.
One option for quantitative assessment of climate effects of single aircraft trajectories relies on spatially and temporally resolved climate change functions (CCFs) and their algorithmic version (aCCFs). Such aCCFs estimate radiative forcing or temperature change of aircraft emissions depending on their time and location of emission. However, the confidence of these estimates is limited by uncertainties arising at several levels: estimates of aircraft emissions, model representations and the probabilistic nature of numerical weather prediction (NWP) forecasts, and the analysis and representation of atmospheric processes when modelling climate effects and associated uncertainties. Aviation’s climate effects originate from perturbations of atmospheric concentrations in the upper troposphere and lower stratosphere (UT/LS), the principal region where contrails, NOₓ, and other aerosols exert their influence. Consequently, our uncertainty framework explicitly incorporates information from both observational techniques and numerical simulation models representative for this atmospheric layer.
In this study we present an integrated workflow that combines uncertainties from four principal sources: emissions, NWP forecast spread and skill, representation of atmospheric processes in atmosphere-climate models, and reduced complexity from regressions. In the numerical workflow as explored in our study, each uncertainty source is described either by a probability distribution (normal, log‑normal, or empirically derived) or by an ensemble of realizations. Through Monte‑Carlo sampling we propagate these uncertainties across the physical relationships that couple emissions to climate effect estimates, producing a probabilistic estimate of the net climate‑impact reduction and its confidence interval.
Application of this proposed uncertainty workflow to a set of city‑pair routes demonstrates how uncertainties can be represented with confidence levels, and with the help of hypothesis test, we can evaluate the robustness of individual proposed alternative aircraft trajectories. This numerical workflow allows balancing in fuel consumption, operational cost, and reduction in climate effects in a mathematical and statistical way. Ultimately, such type of workflow is designed for integration into automated flight‑planning and decision‑support systems. Limitations include a possible underestimation or overestimation of uncertainty values and the current lack of systematic observational validation of the aCCFs. Future work will aim to improve scientific understanding on non-CO2 climate effects, and to integrate prevailing uncertainties in an overall decision-making-process.
How to cite: Matthes, S., Dietmüller, S., Dahlmann, K., and Patrick, P.: Identifying confidence intervals for aviation climate effect mitigation potentials – using algorithmic climate change function, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20936, https://doi.org/10.5194/egusphere-egu26-20936, 2026.
Approximately two-thirds of aviation’s climate impact are attributed to contrail cirrus, the clouds resulting from the persistence of initially linear contrails [1]. This persistence can only occur in regions of the atmosphere where the relative humidity w.r.t. ice (RHi) is larger than 100%: these regions are known as ice supersaturated regions (ISSRs). The climate impact of contrail cirrus could be mitigated by means of minor trajectory adjustments that re-route aircraft around ISSRs (or subsets of these regions) at the cost of minor increases in fuel burn [2, 3]. The viability and effectiveness of this mitigation option rely on skillful forecasts of these regions: existing approaches to numerical weather prediction (NWP) have been found to be relatively poor at forecasting such regions of contrail persistence [4, 5]. This lack of skill is attributed to the coarse spatial resolution of such NWP model, simplified treatment of ice clouds, and the scarcity of high-quality measurements of humidity in the upper troposphere.
This study evaluates the ability of in-flight humidity measurements to improve humidity forecasts, and contrail avoidance relying on these forecasts, through an Observation System Simulation Experiment (OSSE). An original RHi forecast is updated by employing 4D-Var data assimilation of simulated humidity data into ERA5 ensembles. A proof-of-concept case study is first presented, using real IAGOS flights: humidity observations from one transatlantic IAGOS flight are used to improve the humidity forecast for another, temporally adjacent, IAGOS flight. The updated forecast, based on the first flight observations, is validated against the independent RHi observations from this second flight, showing an improvement in RMSE relative to the original forecast.
Next, the climate impact and operational cost of the improvements to the forecast are assessed for various simulated scenarios at a fleet-wide scale. The scenarios consist of: 1) 6 different levels of allocation of aircraft in the fleet that are equipped with humidity sensors (0%, 20%,40%, 60%, 80%, 100% of fleet penetration), 2) 4 levels of discrepancy between humidity forecasts and ground truths (10%, 30%, 50%, 70% recall on ISSR prediction), and 3) 3 levels of simulated accuracy of the humidity sensors used (3%, 6%, 12%).
Results show that targeted sensor allocation among a fleet yield increased persistent contrail reduction under realistic forecast discrepancies, supporting scalable aviation climate strategies using on-situ humidity measurements.
[1] Lee et al. (2021). The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018. Atmospheric Environment 244, 117834. https://doi.org/10.1016/j.atmosenv.2020.117834
[2] Teoh et al. (2020). Beyond contrail avoidance: Efficacy of flight altitude changes to minimise contrail climate forcing. Aerospace, 7(9), 121. https://doi.org/10.3390/aerospace7090121
[3] Frias et al. (2024). Feasibility of contrail avoidance in a commercial flight planning system: An operational analysis. Environmental Research: Infrastructure and Sustainability, 4(1), 015013. https://doi.org/10.1088/2634-4505/ad310c
[4] Gierens et al. (2020). How well can persistent contrails be predicted? Aerospace, 7(12), 169. https://doi.org/10.3390/aerospace7120169
[5] Geraedts et al. (2024). A scalable system to measure contrail formation on a per-flight basis. Environmental Research Communications, 6(1), 015008. https://doi.org/10.1088/2515-7620/ad11ab
How to cite: Oostwoud, W., Meijer, V., Smith, J., and Barrett, S.: Improving contrail avoidance through targeted deployment of humidity sensors on aircraft and advanced weather data assimilation., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20759, https://doi.org/10.5194/egusphere-egu26-20759, 2026.
Aircraft emissions play a role in human induced climate change, in particular condensation trails (contrails) formation, NOx and CO2 emissions. Recent years have seen increased research output in contrail studies and mitigation. Geo-engineering has gained attention in recent decades, with the objective to increase the global albedo resulting in reduced radiative forcing. Scenarios for geo-engineering include stratospheric aerosol injection (SAI), Marine Cloud Brightening (MCB), silver iodide injection as well as more niche scenarios. The interaction between aviation and geo-engineering remains underexplored. We explore the role of geo-engineering on contrail formation, persistence and aircraft plume chemistry employing the Aircraft Plume Chemistry, Emissions, and Microphysics Model (APCEMM). We apply this to jet fuel A-1 as well as potential alternative fuels with respective emission indices’ parameters including Synthetic aviation fuels (SAFs), hydrogen internal combustion jet engines and ammonia. We evaluate the chemistry background composition using theoretical adjustments and the G6-Sulfur experiment in CMIP6 model outputs. We explore how the result of increased particulate matter from increased aerosol number density, resulting from geo-engineering, facilitate the seeding of contrail formation. We find changes in ice crystal number density, heterogenous reaction rates of nitric acid, ozone perturbations optical depth of contrails, contrail lifetimes and total extinction, providing insights into the radiative forcings from SAI influenced contrails. [An increase in ice crystal number density is observed due to an abundance of sulfate aerosols acting as condensation nuclei. Reductions in the efficacy of alternative fuels such as hydrogen at minimising contrails, both in lifetime and forcing, when background aerosols replace soot as nucleating particles. Enhanced heterogonous reaction rate were found to increase HNO3 with SAI by 5 % for a 50 % increase in SO2 ]
How to cite: Foster, A., Khan, A., Shallcross, D., and Lowenberg, M.: The impact of Stratospheric Aerosol Injection and other geo-engineering scenarios on aircraft plume chemistry and contrails from conventional and alternative fuels, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18790, https://doi.org/10.5194/egusphere-egu26-18790, 2026.
Contrails and contrail cirrus, induced by civil aviation and posing a radiative warming threat to the climate, form and persist at high altitudes in the upper troposphere in regions characterized by low temperatures and high relative humidity with respect to ice (RHice). Both temperature and humidity are critical variables controlling the formation of contrails and contrail cirrus. Variability in RHice in the upper troposphere is intrinsically associated with changes in ambient temperature. Recent years have seen record-breaking surface temperatures, particularly across continental regions. However, the relationship between upper-tropospheric temperature and humidity and surface temperatures remains poorly understood.
This work uses 30 years of airborne temperature and relative humidity measurements from the European Research Infrastructure IAGOS to investigate changes in Potential Contrail Cirrus Regions (PCCRs) in relation to surface temperature extremes (heatwaves and cold waves) over Europe. Surface temperature extremes are identified for each season using temperature measurements in the planetary boundary layer (<1.5–2 km altitude), applying statistical methods and significance tests. This classification provides the basis for examining the seasonal variability of RHice and PCCRs during heatwaves and cold waves. This study aims to improve understanding of how an increasingly warming world may affect the formation of contrails and contrail cirrus.
How to cite: Li, Y., Rohs, S., Bundke, U., Smit, H. G. J., and Petzold, A.: Insights into Potential Contrail Cirrus Regions During Surface Temperature Extremes from Three Decades of Airborne Measurements, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17067, https://doi.org/10.5194/egusphere-egu26-17067, 2026.
International shipping is a major source of anthropogenic sulfur emissions, affecting both climate and air quality. The high fuel sulfur content (FSC) in marine fuels leads to high sulfur dioxide (SO2) emissions and subsequent sulfate aerosol particle formation in the atmosphere, particularly over major shipping lanes and along coastal regions where cloud susceptibility is high. Sulfate aerosol particles act as cloud condensation nuclei (CCN) and can alter the microphysical and radiative properties of clouds, enhancing cloud albedo and exerting a net cooling effect on the climate. At the same time, sulfate aerosol particles deteriorate air quality and pose risks to human health. To mitigate the adverse health effects, the International Maritime Organization (IMO) implemented the “IMO2020” regulations, which reduced the maximum allowed FSC in marine fuels from 3.5% to 0.5% as of January 2020. However, the resulting reduction in sulfate aerosol particle burden also diminishes the aerosol-induced cooling effect, potentially unmasking part of the previously suppressed anthropogenic warming. In this thesis, aerosol-climate model simulations suggest that IMO2020 regulations led to a loss of aerosol-induced cooling of +67 mW m−2 globally, while the concentration of ship-induced fine particulate matter simultaneously dropped by ~60% across continents. Sensitivity simulations to test the effects of hypothetical region-specific regulation strategies demonstrate that the strongest air quality improvements occur when IMO2020 regulations are enforced in coastal regions where population density is high, while open-ocean regulations have little effect on air quality. However, the largest loss of aerosol cooling is also attributable to FSC reductions in coastal regions, where ship traffic is dense and cloud albedo highly susceptible to aerosol perturbations. Consequently our results highlight a fundamental trade-off: efforts to reduce air pollution caused by the shipping sector simultaneously lead to a substantial loss of aerosol-induced cooling. The balance between air quality improvements and retaining the cooling strongly depends on the spatial distribution of ship traffic, population exposure and cloud cover. Future research should explore the trade-off across multiple models and for region-specific regulation strategies under different climate change scenarios.
How to cite: Isselhorst, L., Righi, M., Schmidt, A., and Lauer, A.: Fundamental trade-off between climate and air quality from sulfur reductions in marine fuels , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9150, https://doi.org/10.5194/egusphere-egu26-9150, 2026.
Accurately constraining real-world vehicular emissions remains a major challenge for megacities where certification values often fail to represent on-road behaviour. To address this gap for Delhi, we conducted near-tailpipe measurements of Black Carbon (BC), Carbon Monoxide (CO), and Carbon Dioxide (CO2) from a representative fleet of 42 gasoline Two-Wheelers (2Ws) and Light-Duty Vehicles (LDVs) across Bharat Stage (BS) III, IV, and VI categories. Emissions were quantified under controlled idling and high-idling conditions using an Aethalometer AE33 for BC and Horiba/LI-850 analysers for CO and CO2, with fuel-based emission factors derived through carbon-balance calculations. To incorporate real-world usage, active in-use fleet fractions (45% for 2Ws and 60% for LDVs) were applied to estimate idling-related fuel demand. Annual idling fuel consumption was 24.93 × 103 ton for Two-Wheelers and 79.75 × 103 ton for LDVs, corresponding to 5.7% and 14% of their respective total fuel use. These mode-specific contributions were used as weighting factors for composite BC, CO, and CO2 emission factors. Measured idle emission factors averaged 1.24 mg km-1 (BC) and 5.11 g km-1 (CO) for Two-Wheelers, and 0.10 mg km-1 (BC) and 0.72 g km-1 (CO) for Light-Duty Vehicles. BS VI vehicles exhibited more than an order-of-magnitude reduction in BC compared with BS III–IV, confirming the efficiency of newer emission-control technologies. However, strong heavy-tailed behaviour was observed: approximately 30% of the fleet contributed nearly 80% of total BC emissions, indicating a pronounced super-emitter segment. Fuel-scaled annual emissions for Delhi’s gasoline fleet were estimated as 0.029 Gg yr-1 (BC), 100.86 Gg yr-1(CO), and 2.86 Mt yr-1 (CO2). The findings underscore the substantial impact of ageing and poorly maintained vehicles on urban pollution burdens and provide high-resolution, measurement-based emission factors essential for improved inventories and targeted mitigation strategies.
How to cite: Ali, A., Haque, A., Pandey, A., Singh, V., and Kumar, M.: Influence of Fuel Standards on Vehicular Emissions: Assessing the Impact of Bharat Stage Regulations in Urban Idling Conditions (Black Carbon and Carbon Monoxide), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-980, https://doi.org/10.5194/egusphere-egu26-980, 2026.
Spatial interpolation methods (SIMs) are widely used in local environmental assessments, yet their computational cost and performance vary substantially across datasets. High resolution modelling of elements of local environmental studies, including pollutant concentrations and noise, is often computationally demanding. As a result, SIMs are widely used to estimate values between modelled points and construct exposure contour maps. The choice of interpolation method therefore has a direct influence on both computational efficiency and the accuracy of subsequent impact assessments.
This work develops a structured framework for comparing and selecting SIMs by examining how they differ in three practical respects: how strongly they smooth or preserve sharp spatial features, how sensitive they are to the spacing of available data points, and how computationally demanding they are to apply. To demonstrate these distinctions, we analyse pollutant concentration and noise datasets using airport sites as the case study. High resolution model outputs are used as reference values, against which we evaluate interpolated estimates derived from coarser grids across a range of SIMs. This enables a systematic assessment of method behaviour under realistic sampling conditions typical of local environmental modelling.
We compare commonly used SIMs including nearest neighbour, inverse distance weighting, linear and Clough–Tocher triangulation, radial basis functions and several kriging variants across multiple sampling densities. Errors relative to fine grid values are analysed together with measures of local spatial gradients, allowing us to identify when methods smooth peaks, distort steep transitions or perform reliably in more uniform regions. The study also reviews recent machine learning and hybrid interpolation approaches and summarises current software support for SIMs.
The outcome has two components. First, we present a decision tree that groups SIMs according to their ability to represent sharp spatial changes, their sensitivity to spatial sampling and their computational requirements. This framework provides a general guide for method selection in local environmental assessments. Second, the case studies show that interpolation performance depends strongly on the structure of the dataset being modelled, meaning that method choice should always be verified for the specific application. Together, the framework and case study findings offer both a basis for SIM selection and insight into how different methods perform in practice when balancing accuracy and computational cost.
How to cite: Percival, B., Lim, L., Zhao, X., Li, C., Kolb, M., Muslić, A., Türkyilmaz, B., and Yin, F.: A guide to spatial interpolation methods for local environmental assessments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7091, https://doi.org/10.5194/egusphere-egu26-7091, 2026.
How to cite: Luo, Q. and Huang, B.: The Hidden Shipping Carbon Cost of Extreme Weather: Unveiling the Hydrodynamic Penalty of Hurricane Evasion, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5344, https://doi.org/10.5194/egusphere-egu26-5344, 2026.
LNG adoption in shipping is often presented as a route to lower air-pollutant emissions and meet tighter sulphur limits under IMO 2020 and EU in-port requirements. The climate side is trickier: LNG-related methane (CH4) emissions depend heavily on CH4 slip, and that matters more under new EU policies that price and regulate greenhouse gases (GHG) emissions. Since January 2025, the FuelEU Maritime applies well-to-wake GHG-intensity targets, while from January 2026, CH4 emissions from maritime transport also fall under the EU Emissions Trading System.
Here we present results on shipping CH4 emissions over Spain derived from a near-real-time, high-resolution Automatic Identification System (AIS)-based emission model developed within the RESPIRE-CLIMATE national project, which received formal endorsement from the WMO-IG3IS initiative. Using 2019–2025 AIS trajectories, we quantify CH4 slip from LNG-fuelled ships using engine-type- and load-dependent emission factors. The system is fully operational and generates daily outputs per ship type on a 0.01°×0.01° grid.
Across Spanish waters, we detect a marked increase in LNG-related activity after 2022, consistent with Europe’s rapid shift in gas supply chains following the war in Ukraine. Spain is indeed a major LNG gateway in Europe, with roughly one-third of Europe’s regasification capacity, which supports high LNG carrier traffic and enables re-export flows.
A Barcelona case study shows how this trend intersects with intensified LNG operations, reaching 618 port calls of LNG-fuelled ships during 2023. Results highlight where and when CH4 slips concentrate near ports and in traffic lanes and which ship types are driving the largest emission peaks. They also show how, for several major cruise and cargo ships, CH4 slip can substantially change the CO2-equivalent balance of LNG-fuelled ships under certain operating profiles.
The results presented in this study can contribute to the monitoring, reporting, and verification activities of GHG emissions from the maritime transport.
How to cite: Lombardich, I., Castesana, P., Legarreta, O., Tena Medina, C., Piñero-Megías, C., Viñas Ferran, A., Gehlen, J., Rizza, L., Pérez García-Pando, C., and Guevara Vilardell, M.: Assessing the climate footprint of LNG as a marine fuel: evidence from a high-resolution AIS-based emission model for Spain, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8063, https://doi.org/10.5194/egusphere-egu26-8063, 2026.
Emissions from transport contribute significantly to anthropogenic climate change, and evaluating the climate effect induced by aerosols from transport in different emission scenarios usually relies on computing-intensive general circulation models (GCMs). As an alternative approach, simple climate response functions between the emissions from a given sector and their resulting climate impact are desirable, to evaluate emissions scenarios in a more efficient way.
In this study, the Perturbed Parameter Ensemble (PPE) method is applied to generate such simple response functions (emulators), based on simulations with the global aerosol–chemistry–climate model EMAC equipped with the aerosol microphysical submodel MADE3. Emission rates of four species from land-based transport emissions (NOx, SO2, black carbon and organic carbon) are varied simultaneously across a four-dimensional parameter space using the Latin Hypercube method, which generates 41 representative combinations. Global model simulations are conducted for each of these combinations and used to train Gaussian Process (GP) emulators that represent the aerosol climate effects arising from emission changes. Finally, a variance-based sensitivity analysis is performed to quantify the relative contributions of individual emission parameters to the aerosol-induced radiative forcing change.
The emulators are generated and evaluated separately in five world regions: Europe, Asia, North America, South America, and the rest of the world. The results demonstrate that the emulators successfully capture the relationship between aerosol-climate effects and emissions and accurately reproduce the model results. The results further reveal pronounced regional differences in the relative contributions of emission parameters to the aerosol climate effect. In South America, organic carbon emissions account for approximately 55% of the land-transport-induced climate effect, with SO₂ contributing the remaining ~45%. By contrast, in all other regions, SO₂ contributes more than 90% and represents the dominant emission parameter driving the aerosol-induced change in radiative forcing.
How to cite: Li, J., Righi, M., Hendricks, J., Kaiser, J. C., Beer, C. G., and Schmidt, A.: Emulating the effect of land-based transport emissions on aerosol-induced radiative forcing change based on a perturbed parameter ensemble method, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9063, https://doi.org/10.5194/egusphere-egu26-9063, 2026.
Ship exhaust emissions are recognized as a major source of air pollution in coastal regions and an important target of international maritime regulations. With the strengthening of fuel sulfur content regulations, there is an increasing demand for quantitative emission estimates that explicitly account for operational conditions and regulatory application criteria. The U.S. Environmental Protection Agency (EPA) provides guidelines for ship emission estimation, including engine power and load factor calculations based on AIS-derived operational data, low-load operation adjustments, and the application of fuel sulfur regulations. In this study, these EPA-recommended procedures are implemented as a computational framework and algorithm applicable to large-scale AIS data, and are applied to ships operating in Korean waters. The analysis targets oceangoing vessels operating in Korean waters during the period 2021–2024, using AIS-based operational data combined with detailed ship specification data from IHS. Operating time is derived from the time differences between consecutive AIS records, while engine load factors are calculated using relationships between vessel speed and Maximum speed, as well as between draft and Maximum draft. Operating conditions with load factors below 20% are defined as low-load operation, and corresponding low-load adjustment factors recommended by the EPA are applied. Fuel sulfur content regulations are incorporated by reflecting time-dependent and spatially differentiated regulatory criteria to classify fuel types, and emission factors are applied at the level of individual AIS records according to these conditions. Through this procedure, ship emissions are estimated while simultaneously accounting for operational characteristics and regulatory applicability. The estimated pollutants include NOx, CO, HC, PM10, PM2.5, SO₂, and CO₂. The results indicate that low-load operation accounts for 42.56% of all valid AIS records, including 13.69% under stationary conditions (SOG = 0) and 28.87% under low-speed operation. The average SO₂ emission intensity is estimated at 2446.95 g/h in non-regulated areas and 20.30 g/h in regulated areas. These results suggest that ship emission characteristics in Korean waters vary substantially depending on operational conditions and the application of time and space dependent fuel sulfur regulations. The resulting emission inventory enables comparisons of emission characteristics across regions and periods, and can serve as a basis for discussions related to coastal air quality analysis, evaluation of emission control effectiveness, and assessments of emission changes under different regulatory scenarios.
How to cite: An, M., Lee, J., and Kim, T.: Big Data–Driven Emission Inventory of Ship Exhaust Gases Considering Operational Scenarios, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16312, https://doi.org/10.5194/egusphere-egu26-16312, 2026.
Climate change is expected to alter wave conditions across the world’s oceans, potentially affecting ship navigation safety and maritime transportation efficiency. In East Asia, where international shipping routes are highly concentrated, understanding future changes in wave climate is particularly important for assessing climate-related maritime risks. In this study, future changes in significant wave height (Hs) along major shipping routes in East Asia are investigated using regional climate projections from the CORDEX framework. Significant wave height data for a historical reference period and future climate scenarios were analyzed to examine changes in annual and seasonal mean conditions as well as high-wave occurrences. The analysis focuses on route-based characteristics by extracting Hs along representative major shipping corridors, allowing spatial variations in wave conditions to be evaluated from an operational maritime perspective. Changes in the frequency of high-wave conditions exceeding selected Hs thresholds were also assessed to identify potential increases in navigational risk. The results indicate that future changes in significant wave height exhibit pronounced spatial and seasonal variability across East Asian seas. While mean Hs changes are modest in some regions, several shipping route segments show an increase in high-wave occurrences, particularly during winter seasons. These changes suggest that climate-driven modifications of wave conditions may lead to increased operational challenges along specific routes, even in the absence of large changes in mean wave height. This study highlights the importance of route-oriented wave climate assessments for maritime applications and demonstrates the usefulness of CORDEX regional climate projections for evaluating future wave-related risks. The findings provide a basis for climate adaptation strategies in maritime transportation, including route planning and risk management under future climate conditions.
How to cite: Kim, T. and Cha, D.-H.: Future Changes in Significant Wave Height along Major Shipping Routes in East Asia using CORDEX-EA data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16902, https://doi.org/10.5194/egusphere-egu26-16902, 2026.
The increasing intensity of typhoons associated with climate change has significantly elevated the risk of anchor dragging of vessels sheltering in coastal anchorages, leading to collisions, groundings, and secondary maritime accidents. Despite its operational importance, anchor dragging under extreme weather conditions remains poorly understood and is rarely addressed as a predictive problem. This study proposes a data-driven framework to detect and predict anchor dragging of anchored vessels during typhoon events by integrating vessel motion data with meteorological and oceanographic forcing. Automatic Identification System (AIS) data were combined with typhoon track and intensity information, high-resolution marine weather fields, and bathymetric data for Typhoon Kong-Rey (2018), which directly affected Jinhae Bay, one of the largest typhoon shelter areas in Korea. Anchored vessels were identified using speed-based criteria, and vessel-specific anchor circles were constructed by estimating anchor positions from AIS heading information, anchor chain length, and vessel dimensions. Anchor dragging events were labeled based on deviations from the anchor circle, supported by visual verification. To predict dragging occurrence, a genetic algorithm-based automated machine learning framework (TPOT) was applied to optimize preprocessing steps, feature selection, model structure, and hyperparameters. The explanatory variables included vessel kinematics, wind speed and direction, atmospheric pressure, and local water depth. The resulting model successfully distinguished high-risk vessels during peak typhoon influence, demonstrating strong predictive performance and robustness across vessel types. The proposed approach provides a probabilistic early-warning capability for anchor dragging, enabling prioritized monitoring of high-risk vessels rather than uniform risk management. This framework supports proactive decision-making for Vessel Traffic Services (VTS), port authorities, and emergency response agencies, and contributes to reducing cascading maritime accidents under intensifying extreme weather conditions.
How to cite: Lee, J., An, M., Kim, T., and Do, Y.: Data-Driven Prediction of Anchor Dragging of Vessels under Typhoon Conditions , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16188, https://doi.org/10.5194/egusphere-egu26-16188, 2026.
Ocean currents play a key role in determining optimal maritime routes, particularly in regions characterized by complex mesoscale and coastal dynamics. This study assesses the sensitivity of weather routing to ocean model resolution by comparing optimal routing paths obtained with the VISIR-2 model [1] forced by ocean circulation models with different spatial resolution. The Bastia (Corsica)–Nice (France) route was selected as a representative ferry corridor in the Mediterranean Sea. The route crosses the Ligurian Sea, a region characterized by a strong boundary current and intense mesoscale activity, making it a suitable test case to assess the sensitivity of optimal ship routing to ocean current resolution. Optimal routes between the two ports are computed daily for one year using: (i) the 4.2 km resolution Copernicus Marine Environment Monitoring Service (CMEMS) Mediterranean reanalysis product [2] (reference experiment), and (ii) a regional NEMO configuration at 2 km horizontal resolution covering the broader Lingurian Sea (high-resolution experiment). The simulated vessel is a Ro-Pax passenger ferry with an overall length of 125 m, whose propulsion characteristics and CO₂ emission model are derived from [3]. In both experiments, time-varying ocean currents are used by VISIR-2 to compute time-optimal and least-CO₂ trajectories under realistic vessel dynamics. Wave conditions are also accounted for using the CMEMS wave dataset [4]. The comparison focuses on route geometry, travel time, CO₂ emissions and seasonal variability. The analysis aims to assess how differences in ocean model resolution influence optimal maritime routing.
References:
[1] Mannarini, G., Salinas, M. L., Carelli, L., Petacco, N., and Orović, J.: VISIR-2: ship weather routing in Python, Geosci. Model Dev., 17, 4355–4382, https://doi.org/10.5194/gmd-17-4355-2024, 2024.
[2] Mediterranean Sea Physics Reanalysis. E.U. Copernicus Marine Service Information (CMEMS). Marine Data Store (MDS). DOI: 10.25423/CMCC/MEDSEA_MULTIYEAR_PHY_006_004_E3R1 (Accessed on 13-01-2026)
[3] Mannarini, G.; Carelli, L.; Orović, J.; Martinkus, C.P.; Coppini, G.: Towards Least-CO2 Ferry Routes in the Adriatic Sea. J. Mar. Sci. Eng. 2021, 9, 115. https://doi.org/10.3390/jmse9020115
[4] Mediterranean Sea Waves Reanalysis. E.U. Copernicus Marine Service Information (CMEMS). Marine Data Store (MDS). DOI: https://doi.org/10.48670/mds-00376 (Accessed on 13-01-2026)
Acknowledgement: This research has received funding from the European Union’s H2020 innovation programme under the Grant Agreement No. 101112752.
How to cite: Metheniti, V., Parasyris, A., Alexandrakis, G., Kozyrakis, G., Kampanis, N., and Mannarini, G.: Assessing the impact of ocean circulation model resolution on optimal maritime routing in the Ligurian Sea using VISIR-2, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19086, https://doi.org/10.5194/egusphere-egu26-19086, 2026.
The maritime sector, traditionally one of the hardest sectors to decarbonize, is currently rapidly changing driven by demands for emission reductions. Increasingly stringent regulatory frameworks, including the International Maritime Organization’s (IMO) net-zero ambitions and the European Union’s (EU) greenhouse gas (GHG) reduction targets are driving the maritime sector to adopt low-emission technologies and practices. Increased attention has been previously allocated by the scientific community to the exploration of alternative fuels and efficiency improvements. Nevertheless, the full life-cycle implications of completely electrifying passenger vessels remain insufficiently assessed.
This study estimates the emission pay-back time associated with replacing a conventional marine gas oil (MGO) powered passenger vessel with a concept vessel fully powered by battery and rigid auxiliary sails. The analysis assumes one year of continuous operation for both vessels along the traditional Norwegian coastal route. A life-cycle assessment (LCA) framework is applied. The system boundaries are covering the production of lithium iron phosphate (LFP) batteries with a net capacity of 60 MWh; sails manufacturing, installation, operation, and energy savings; charging infrastructure; energy requirements for vessel’s operation and end-of-life treatment. The resulting total carbon footprint for one year of operation is compared with the one corresponding to the reference vessel, the fossil-fuel powered one, where manufacture, operation, and disposal of diesel engines are considered.
The vessel’s operational energy demand is derived from real-world timetable data and reflects seasonal variations. The energy requirements range between 642 and 666 MWh per roundtrip. The assessment takes into consideration the battery losses as well as the depth-of-discharge constraints. Battery charging is modelled using realistic electricity mixes from Norwegian bidding zones NO2 to NO5 which are corresponding to the geographical route of the vessel. In contrast to the generic national-average electricity mixes usually applied in LCA studies, this dynamic approach for electricity modelling considers the spatial and temporal variations in electricity generation sources. This has a direct impact on the associated emission intensities of the electricity consumption of the vessel. The fossil-fuelled reference vessel requires approximately 50 000 MWh of gross energy annually, assuming an average engine efficiency of 37% and auxiliary heating partly supplied by oil-fired boilers. In contrast, the battery-electric vessel requires about 28 000 MWh per year, enabled by an optimized system design, high propulsion efficiency (around 90%), and improved heat recovery.
Our preliminary results highlight that the emissions pay-back period is highly sensitive to the carbon intensity of the electricity supply as well as to the spatial distribution of charging infrastructure localized in the harbours where the vessel stops. We find as critical for the operational feasibility the availability of high-power chargers in ports such as Ålesund and Trondheim.
Under the current Norwegian grid conditions and the power purchase agreements in place modelled here in the study, the pay-back time is sufficiently short. We therefor find that battery electrification can be one of the near-term decarbonization strategy for the maritime sector. Overall, our results show that full replacement of fossil-fuel coastal vessels with battery-electric solutions can deliver substantial GHG reductions, supporting both IMO and EU climate objectives.
How to cite: Iordan, C.-M., Ravi, R., Viken Strand, A., Schluter, K. M., and Bruyat, A.: Emission pay-back time of battery-powered versus fossil-fuel powered passenger vessel , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19369, https://doi.org/10.5194/egusphere-egu26-19369, 2026.
Posters virtual: Tue, 5 May, 14:00–18:00 | vPoster spot 5
EGU26-15593 | ECS | Posters virtual | VPS3
Horizontal grid and meteorology resolution impacts on aviation’s air quality impactsTue, 05 May, 14:51–14:54 (CEST) vPoster spot 5
Simulations of aviation's air quality impacts near airports are critical for enhancing our understanding of how aviation impacts air quality regionally, and the potential effects of sustainable alternatives. In order to better understand such impacts, a research to investigate the effects of the resolution of the simulation grid and of the meteorology inputs on the air quality impact estimates due to aircraft emissions, specifically in the context of stretched gnomonic cubed-sphere grids for the simulation of a specific area was conducted. Such grids allow for the possibility of having a region with finer grid elements while coarsening the grid outside a specified area.
The research questions that the present research effort aims to address are: which parameter (grid resolution or meteorology resolution) impacts most the simulations, how grid and meteorology resolution impact air quality estimates, and whether stretched grids can be used for regional simulations.
To address the matter, we use the distributed-memory, high-performance version of the GEOS-Chem atmospheric chemistry-transport model to simulate the evolution of aviation attributable to Landing and Take-Off operations (LTO) emissions throughout the year of 2019. The LTO emissions were obtained from the OpenAVEM emissions inventory, whereas the remaining non-aviation emissions were taken from the default GCHP databases.
Three different grid resolutions were chosen to evaluate the impact of the horizontal grid resolution: C24, C36, and C48, with grid cell lengths ranging between 40 km, 30 km, and 20 km, respectively. All grids use the same stretch parameters, i.e., target latitude, target longitude, and stretch factor. These parameters were set so as to have a finer resolution around Europe. For the meteorology sensitivity, two resolutions were used, 2 ° ×2.25 ° and 0.5 ° ×0.625 ° from MERRA2 for the three grid resolutions aforementioned.
A comparison between the area weighted concentrations for NO2, PM2.5, and O3 showed that the resolution of the meteorology plays a more important role than the horizontal grid resolutions, for the resolutions tested. For the human health impacts, the deaths attributable to each component have also been estimated and compared for each grid resolution.
How to cite: Kavabata, L., Quadros, F., Meijer, V., Snellen, M., and Dedoussi, I.: Horizontal grid and meteorology resolution impacts on aviation’s air quality impacts, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15593, https://doi.org/10.5194/egusphere-egu26-15593, 2026.
