However, our understanding of these processes is still incomplete. Despite being a crucial milestone for reaching accurate projections of future climate change in Polar Regions, deciphering the interplay between the atmosphere, land ice and sea ice on different spatial and temporal scales, remains a major challenge.
This session aims at showcasing recent research progress and augmenting existing knowledge in polar meteorology and climate and the atmosphere-land ice-sea ice coupling in both the Northern and Southern Hemispheres. It will provide a setting to foster discussion and help identify gaps, tools, and studies that can be designed to address these open questions. It is also the opportunity to convey newly acquired knowledge to the community.
We invite contributions on all observational and numerical modelling aspects of Arctic and Antarctic meteorology and climatology, that address atmospheric interactions with the cryosphere. This may include but is not limited to studies on past, present and future of:
- Atmospheric processes that influence sea-ice (snow on sea ice, sea ice melt, polynya formation and sea ice production and transport) and associated feedbacks,
- The variability of the polar large-scale atmospheric circulation (such as polar jets, the circumpolar trough and storm tracks) and impact on the cryosphere (sea ice and land ice),
- Atmosphere-ice interactions triggered by synoptic and meso-scale weather phenomena such as cold air outbreaks, katabatic winds, extratropical cyclones, polar cyclones, atmospheric rivers, Foehn winds, and heatwaves,
- Role of clouds in polar climate.
- Role of aerosols, such as black carbon, organic carbon, dust, volcanic ash, microplastics, pollen, sea salt, diatoms, bioaerosols, bacteria, in snow/ice melt and albedo changes.
- Teleconnections and climate indices and their role in land ice/sea ice variability.
Presentations that include new observational (ground and satellite-based) and modeling methodologies specific to polar regions are encouraged. Contributions related to results from recent field campaigns in the Arctic and in the Southern Ocean/Antarctica are also welcome.
Orals: Mon, 4 May, 08:30–12:30 | Room L2
Warming on Svalbard is occurring up to seven times faster than the global average and is driving widespread glacier retreat. In addition to rising air temperatures, light absorbing particles (LAP; including black carbon and mineral dust) can enhance snow and ice melt by reducing surface albedo. While black carbon has been studied extensively on Svalbard, mineral dust remains relatively understudied despite growing evidence that high latitude dust emissions may increase due to decreases in snow cover and glaciers retreat.
To address this knowledge gap, we analyzed mineral dust and black carbon in seasonal snow and firn cores collected from twelve spatially distributed Svalbard glaciers between 2022 and 2026. Dust concentrations and deposition rates were quantified using gravimetric filtration and ICP-MS, while dust mineral composition was characterized using X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy. Black carbon was measured on select firn samples using a Single Particle Soot Photometer.
Results show pronounced seasonal variability, with low winter dust concentrations and enhanced summer–fall deposition, as well as substantial spatial variability in dust concentration, mineralogy, and spectral reflectance. Winter dust concentrations ranged from 0.3 to 17.6 µg g⁻¹ (median 0.9 µg g⁻¹), with deposition rates between 0.1 and 1.5 g m⁻² (median 0.4 g m⁻²). Mineralogical analyses reveal abundant sheet silicates and common rock-forming minerals across all sites, with carbonates largely restricted to central Svalbard glaciers, indicating variability in dust sources and depositional processes. Radiative transfer modeling demonstrates that mineral dust dominates LAP driven albedo reductions, exceeding contributions from black carbon. These findings highlight the growing importance of mineral dust for Svalbard snow and ice melt in the warming Arctic.
How to cite: Kaspari, S., Isaksson, E., Orme, O., Gallet, J.-C., Hodson, A., Hartz, W., Spoloar, A., Scoto, F., Diaz Vega, D., and Kraics, T.: Mineral Dust in Seasonal Snow and Firn on Svalbard Glaciers: Deposition Rates, Composition, and Albedo Impacts, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14783, https://doi.org/10.5194/egusphere-egu26-14783, 2026.
In recent decades, the Svalbard archipelago has experienced the fastest warming on Earth, with rates approximately four times higher than the global average. Due to Arctic amplification, the weakening of the polar vortex, rising sea surface temperatures, and retreating sea ice have led to increasingly frequent intrusions of warm, moist air masses from the North Atlantic, resulting in winter temperature anomalies often accompanied by liquid precipitation. In turn, winter rain-on-snow (RoS) events have become more frequent and intense in recent years, causing complex and unprecedented interactions with ecosystems, hydrology, transportation, and infrastructure. Precipitation can substantially alter the physical state of snow cover by increasing liquid water content (LWC) and enhancing surface runoff, while refreezing of meltwater can form basal and internal ice layers, limiting accessibility to the underlying tundra for wildlife such as reindeer. In addition, RoS can also promote early seasonal snowmelt, altering nutrient release timing in Arctic ecosystems and increasing risk to local communities due to flooding and avalanches.
Although remote sensing and atmospheric reanalyses have proven effective for detecting RoS, accurate and reliable in situ measurements remain critical for bridging the multiscale gap . Ground-based snow data not only provide essential validation, but also offer the spatial and temporal resolution needed to resolve rapid, small-scale physical processes within the snowpack. To this end, a comprehensive snow observation system was installed in Ny-Ålesund (Western Spitsbergen, Svalbard) at the end of 2020, providing continuous, high-resolution measurements of several key parameters, including snow depth, SWE, albedo, and vertical profiles of snow temperature and LWC. Over the past five years, the system has been able to record both the seasonal evolution of the snowpack, generally lasting from November to the end of May, and the short-lived perturbations triggered by RoS events, improving our understanding of Arctic snowpack dynamics during extreme events. Here we present the instrumental setup, the main observational results collected between 2020 and 2025, and discuss the diagnostic parameters relevant for RoS process studies and model evaluation.
How to cite: Scoto, F., Salzano, R., Mazzola, M., and Spolaor, A.: A Comprehensive Snow Monitoring System to Detect the Impact of Rain-on-snow (ROS) at Ny-Ålesund, Svalbard , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13536, https://doi.org/10.5194/egusphere-egu26-13536, 2026.
Snow plays a critical role in energy budget by reflecting a significant portion of incoming solar radiation, thereby influencing local and global climate dynamics. However, the state-of-the-art climate models still face challenges to simulating global snow amount partly due to inadequate representation of snow albedo. Current models predominately parameterize snow albedo as an age-dependent, exponentially decaying function, which oversimplify its complexity. Also, most of these models neglect the deposition of aerosols (such as dust, black and organic carbons) and their ability of absorbing visible part of solar radiation, leading to reduced albedo and accelerated snowmelt. This “snow darkening effect” process is essential for improving the transient simulation of snow for climate and enhancing our understanding of climate feedback mechanism. To incorporate this phenomenon in ORCHIDEE, the land surface component of IPSL’s Earth System Model, we have implemented a comprehensive tracer framework that simulate the deposition and vertical transport of four log-normal modes of dusts, hydrophobic and hydrophilic black and organic carbons within snowpack. In order to enhance the snow aging processes, a snow metamorphism approach has been used that explicitly simulates the physical evaluation of snow optical diameter and sphericity, rather than relying on a simple chronological aging parametrization. To replace the empirically decaying albedo parametrization with a physics-based impure snow albedo, we have employed unique combination of Warren-Wiscombe’s uni-directional snow radiative transfer scheme with online optical property calculations of snow using Khokhanovsky’s scheme and mie-theory based offline aerosol optical properties. This enhanced physical representation of snow albedo dynamics. For validation against observation, offline ORCHIDEE simulations are conducted using in-situ meteorological forcing and MERRA-2 reanalysis aerosol deposition data across observation sites localized in different climatic areas over the Earth. These sites are selected to represent different aerosols regimes, each characterized by distinct dominant aerosol species. In these simulations, as snowpack develops seasonally, it harnesses aerosols deposited on the surface which are subsequently buried by additional snowfall and redistributed during melt-refreeze cycles. Consequently, snow albedo fluctuates, starting at high values following fresh snowfall and decreasing gradually due to increase in snow optical diameter (metamorphism) and accumulation of impurities, influenced by snow liquid content, vertical temperature gradient, aerosol species and deposition rate. The buried aerosols act as a memory and re-emerge at the surface in high concentration during the melting season. This re-exposure further reduces snow albedo, thereby accelerating melt rates. This simulated behavior is validated against in-situ observation of surface aerosol concentration and snow albedo. Through sensitivity experiments isolating the effects of different modes of dusts and other species, we further identified non-linear dynamics that critically influence the timing of snow melt and the end of the snow season.
How to cite: Krishnakumar, S., Ménégoz, M., Albani, S., Dumas, C., Ottlé, C., Dumont, M., Amory, C., Conesa, P., and Balkanski, Y.: Impact of multi-mode and multi-species aerosols on 1D snow simulation at observational sites distributed at different latitudes., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8348, https://doi.org/10.5194/egusphere-egu26-8348, 2026.
Light-absorbing particles (LAPs) such as black carbon, mineral dust, and organic carbon, when deposited on snow, reduce its surface albedo and increase the absorption of solar radiation. This enhanced absorption accelerates snowmelt and alters snowpack dynamics, particularly during the melt season. Field studies have measured seasonal concentrations of LAPs and confirmed their presence and significant effects on snow albedo. Even small quantities of LAPs can measurably reduce reflectance, particularly in the visible spectrum, and lead to earlier melt-out. A snowpack modeling assessment that isolates the individual and combined effects of each particle type under controlled scenarios can improve our understanding of their specific roles in snowpack evolution. Identifying the contribution of different LAPs to albedo reduction and snowpack dynamics is essential for alpine snow hydrology, where snowmelt timing governs runoff generation and water availability, and helps anticipate how LAPs-driven changes may amplify with climate change and reshape mountain hydrological regimes.
We first developed a one-layer energy budget snowpack model based on HyS (De Michele et al., 2013) and applied it over 18 hydrological years (2005–2023) at the Col de Porte experimental site in the French Alps, using local meteorological forcing. The model, referred to as HyS 3.0, was evaluated against long-term in situ measurements of snow depth and snow water equivalent (SWE), confirming its ability to accurately reproduce seasonal snow accumulation and melt dynamics. Due to its simplicity and low computational cost, HyS 3.0 is also well-suited for hydrological applications and sensitivity testing.
To assess the radiative effects of LAPs, we used field measurements of them along with spectral albedo data from two alpine sites Col de Porte (2014) and Col du Lautaret (2016–2018), capturing contrasting snow conditions. These datasets were used to evaluate BioSNICAR radiative transfer model performance, which computes snow albedo based on impurity concentration, grain size, and snow layer structure. After validation, BioSNICAR was used to generate a suite of LAP scenarios with varying concentrations and compositions. The resulting albedo changes were then used as input to HyS 3.0 to simulate the snowpack response under each scenario.
Results from these simulations revealed measurable changes in snowpack behavior, particularly in melt-out timing and snow specific surface area (SSA), compared to clean-snow conditions. This highlights both the direct radiative and indirect metamorphic effects of LAPs on seasonal snow evolution.
This work is supported by the “Light-Absorbing ParticleS in the Cryosphere and Impact on Water ResourcEs (LAPSE)” project, funded by MUR under the PRIN22 program.
How to cite: Norouzi, S., De Michele, C., and Di Mauro, B.: Quantifying the Radiative Impact of Light-Absorbing Particles on Alpine Snowpack Dynamics , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12689, https://doi.org/10.5194/egusphere-egu26-12689, 2026.
The Arctic is warming three to four times faster than the global average due to multiple feedback processes – a phenomenon known as Arctic Amplification. Cloud feedbacks, in particular, represent one of the largest sources of uncertainty in projections of this amplified warming. Relative humidity (RH) is critical to these cloud feedbacks through its influence on cloud formation and radiation balance, yet changes in Arctic RH under a warming climate remain poorly understood.
Using 27 CMIP6 Coupled Model Intercomparison Project (CMIP6) models, this study investigates Arctic RH changes and their drivers by comparing historical conditions (1985-2015) with future projections under SSP5-8.5 (2070-2100). The multi-model mean reveals a robust vertical dipole pattern in surface-temperature-normalized RH changes across the Arctic. Near the surface (1000-925 hPa), RH decreases by up to 2 % K−1 in winter, while mid-tropospheric RH (950-750 hPa) increases. This counterintuitive pattern – surface drying despite increased open ocean from sea-ice loss – is particularly pronounced during autumn and winter. The dipole signal is strongest over regions experiencing substantial sea ice loss, but remains visible at reduced amplitude over persistent ice regions, indicating both local (sea-ice driven) and broader (stability-driven) components to the RH response.
The multi-model mean, however, emerges from markedly different individual model responses. DIPOLE models reproduce the characteristic dipole pattern with drying near the surface and moistening around 1 km above the surface; DECREASE models show drying in both layers; INCREASE models show moistening at both levels. While DIPOLE and DECREASE models both exhibit a dipole pattern over ice-loss regions, INCREASE models do not, suggesting fundamental differences in model physics that are also evident in present-day RH distributions. Cloud liquid and ice water changes do not follow the dipole pattern but instead show increases across all groups, with inter-group differences in magnitude and vertical extent. Cloud liquid water increases peak near 925 hPa in all groups but are strongest over ice-loss regions in DECREASE and DIPOLE models, while DIPOLE models show strong cloud ice increases throughout the lower troposphere (surface–700 hPa), INCREASE and DECREASE models exhibit two distinct maxima at 850 and 500 hPa.
The primary driver of the dipole pattern is the transition from a predominantly stable atmosphere over sea ice (with an RH maximum near the surface) to a well-mixed atmosphere over open ocean (with an RH maximum at cloud base). This physical mechanism suggests that the DIPOLE models have a more realistic representation of moisture in the Arctic boundary layer and its response to sea-ice loss. If further analysis can rule out the behaviour of the INCREASE and DECREASE models, we expect that this will allow us to better constrain Arctic cloud feedbacks.
How to cite: Wüsteney, S., Platis, A., Bange, J., and Pithan, F.: How Changes in Relative Humidity in the Polar Boundary Layer impact Arctic Amplification in Climate Models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20553, https://doi.org/10.5194/egusphere-egu26-20553, 2026.
While mean and extreme snowfall are projected to decline across many mid-latitude regions, particularly those close to the melting point. An opposing signal is expected in high-latitude and high-elevation regions, including the Arctic. Future changes in Northern Hemisphere extreme snowfall are investigated using KNMI’s Large ENsemble TIme Slice (LENTIS) model. Snowfall changes are closely linked to climate warming. Regional present-day seasonal mean climatological temperatures determine the sign of snowfall change through seasonally dependent temperature turning points. These turning points vary between -11℃ and -18℃ for median snowfall, whereas extreme snowfall exhibits higher turning-point temperatures ranging from -4 ℃ to -11℃ across seasons. As a result, increases in median snowfall event frequency and amount are confined to the coldest regions, while extreme snowfall is already increasing across a wider range of regions with higher climatological temperatures. Under warming conditions, sufficiently cold regions are projected to experience substantially larger increases in extreme snowfall frequency (up to 278%), and amount (up to 271%) than in median snowfall (up to 101%, and 152%, respectively). Regions that approach or exceed the melting point are primarily governed by thermodynamic effects, whereas colder regions remain influenced by a combination of thermodynamic and dynamical circulation changes. As snowfall is likely to influence the surface mass balance of the Greenland Ice Sheet, atmospheric circulation patterns over Greenland are examined in detail. Extreme snowfall over Greenland is found to occur predominantly during a dipole in sea level pressure anomalies spanning Greenland and Northern Europe, which promotes the northward transport of warm, moist North Atlantic air. Using the Greenland Oscillation Index (GOI), which quantifies the strength of this dipole, it is found that the projected increase in extreme snowfall is dynamically driven, with a higher frequency of circulation conditions, characterized by an above-median GOI, impacting particularly Eastern, Central and Northern Greenland. These future increases in extreme snowfall arise from more frequent favorable circulation patterns rather than from an intensification of circulation anomalies.
How to cite: Romijn, N., Bintanja, R., van der Linden, E., and Kolbe, M.: Future Changes in Northern Hemisphere Extreme Snowfall, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12858, https://doi.org/10.5194/egusphere-egu26-12858, 2026.
Short-term changes in Arctic sea-ice area are largely driven by weather events such as synoptic-scale cyclones, which typically cause ice loss during warm and stormy conditions in the Arctic. Physical mechanisms of this ice loss include enhanced sea-ice divergence, poleward ice drift, and changes in the surface energy budget due to advection of warm-moist air masses. In extreme cases, enhanced basal melt of sea ice occurs due to upward mixing of relatively warm ocean water. Such anomalous conditions are prolonged when several cyclones follow rapidly on each other, a phenomenon referred to as serial cyclone clustering. Serial cyclone clustering has been identified as a high-impact phenomenon, substantially amplifying wind damage, precipitation, and sea level extremes across several regions of the Earth. However, this weather phenomenon and its impacts have not yet been examined in the polar regions.
Here, we analyze changes in Arctic sea-ice concentration (SIC) for periods of serial cyclone clustering utilizing satellite observations and reanalysis data from 1979-2024. While cyclones generally decrease SIC compared to non-cyclone conditions in cold and warm seasons, the impact of cyclone clusters is approximately twice as strong and persists 2.5 times longer than for solitary cyclones. The amount of SIC-loss due to cyclone clusters scales with the intensity and number of clustered storms, and greater SIC-loss occurs during 2000-2024 compared to 1979-1999.
These findings emphasize the need to better understand drivers of serial cyclone clustering in the Arctic and more generally highlight the relevance of accumulated impacts of clustered weather events for Arctic sea-ice variability. Applying similar frameworks to other types of weather events and other target quantities (e.g. snow accumulation on sea ice or wind-driven ocean currents) could help to further sharpen our understanding of the role of weather extremes in the coupled polar climate system.
How to cite: Aue, L., Tiedeck, S., Finocchio, P., Vihma, T., Uotila, P., Spreen, G., and Rinke, A.: On the relevance of serial cyclone clustering for Arctic sea ice, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9380, https://doi.org/10.5194/egusphere-egu26-9380, 2026.
Compound warm and wet atmospheric events play a key role in driving extreme melt of the Greenland Ice Sheet (GIS), yet the relative contribution of different atmospheric phenomena remains poorly quantified. While atmospheric rivers (ARs) are frequently associated with extreme melt episodes, a systematic attribution of GIS melt to distinct types of atmospheric circulation features is still lacking.
Here, we apply a modified version of the Multi Object Analysis of Atmospheric Phenomena (MOAAP) tracking algorithm, optimized for Arctic conditions, to identify and track ARs, cyclones, jets, and frontal systems over Greenland. We quantify precipitation from each phenomenon. Together with temperature anomalies and surface melt, we relate these to individual phenomena and their compound occurrences. Extreme melt events are identified based on runoff, and attribution is performed by relating runoff to the presence and overlap of tracked phenomena over the ice sheet.
The analysis is applied to ERA5 reanalysis data and to PolarRES regional climate model projections. PolarRES includes a historical period and two RCP4.5 simulations representing distinct storylines. The first is characterized by enhanced Arctic amplification, which refelcts stronger local feedbacks. The second by reduced sea ice cover, which can indicate patterns of change is driven more by sea-ice loss and associated surface processes than by relative amplification of near-surface atmospheric warming. Using these scenarios allows us to investigate how differences in large-scale thermodynamic conditions may influence the atmospheric drivers of GIS melt, while applying the same phenomenon-based attribution framework across present-day and future climates.
By combining Arctic-optimized tracking of atmospheric phenomena with a GIS melt attribution framework, we investigate how extreme GIS melt events relate to specific atmospheric configurations and how these relationships may change under enhanced Arctic amplification or reduced sea ice. This study aims to improve our understanding of compound warm–wet events, their links to different types of atmospheric phenomena, and their role in GIS melt, as well as how they will shape the future GIS melt in climate projections.
How to cite: Vang, A., Muccioli, M., Düsterhus, A., Jomo Danielsen Sørup, H., Mooney, P., and Hesselbjerg Christensen, J.: Attributing atmospheric phenomena driving Greenland Ice Sheet melt and their future changes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5491, https://doi.org/10.5194/egusphere-egu26-5491, 2026.
Large-scale atmospheric circulation exerts a dominant control on the surface mass balance (SMB) of the Greenland Ice Sheet, yet circulation classifications are often optimized for atmospheric variability rather than for surface impacts. Here, we present an impact-oriented classification approach that emphasizes those regions of large-scale atmospheric circulation that are most relevant for Greenland’s SMB. Daily summer (June-August) 500 hPa geopotential height fields over a North Atlantic-Arctic domain encompassing Greenland are classified using self-organizing maps (SOMs). Prior to classification, the geopotential height fields are weighted based on their correlation with Greenland-wide SMB derived from a regional climate model (Modèle Atmosphérique Régional), such that regions exhibiting a strong linkage to SMB variability influence the circulation classification more. The weighting is derived from correlation patterns between geopotential height anomalies and Greenland-wide SMB anomalies, with a scaling factor systematically varied and selected to maximize both the separation of SMB characteristics across circulation regimes and the distinctness of the associated geopotential height composites. The resulting classification yields a set of circulation types that closely relate to differences in Greenland-wide SMB. Compared to unweighted SOM classifications, the impact-weighted approach enhances the separation of SMB responses across circulation regimes. By further analyzing the evolution of circulation regimes and their impact on Greenland’s SMB over time, we aim to improve understanding of changes in large-scale drivers relevant for the Greenland Ice Sheet mass loss.
How to cite: Fipper, J., Sasgen, I., and Abermann, J.: Connecting large-scale atmospheric circulation with Greenland's surface mass balance variability by impact-weighted self-organizing maps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3859, https://doi.org/10.5194/egusphere-egu26-3859, 2026.
The local microclimate is both a key driver and in turn impacted by glacier wastage. Such feedbacks become particularly relevant in rapidly changing regions such as for West Greenland, where e.g. Qaamarujup Sermia has retreated by approximately 2 km between 1930/31 and 2022. This is the site where Alfred Wegener’s last expedition took place and where its members conducted pioneering glaciological and meteorological studies . Starting in 2022, we re-established a spatially distributed monitoring network extending from the coastline to the upper glacier, including automated weather stations, distributed air-temperature and humidity sensors, and surface mass-balance stakes. These observations allow us to investigate how a significant increase in the extent of ice-free valley surfaces caused by glacier retreat influences altitudinal temperature profiles and, ultimately, glacier melt.
Cluster analyses of temperature gradients reveal that the often-assumed environmental lapse rate of −6.5 K per kilometer only applies under certain conditions. In several cases, lapse rates differ markedly between the ice-free valley and the air above the glacier and show complex patterns. We investigate how these patterns are linked to synoptic forcing and cloud conditions, which control the depth and persistence of temperature inversions.
To quantify the implications of these microclimatic structures for glacier melt, we combine the atmospheric observations with high-resolution melt measurements from automated and conventional mass-balance stakes. We find that in recent years, higher melt rates occur under the same air temperature departure as they did in the 1930s. Sparse snow observations indicate that snow accumulation in 1930/31, with a maximum snow height of approximately 2 m, was higher than in the years since 2022, but remains within the range of extreme snow amounts as for instance represented in the CARRA reanalysis period (1991-2024).
Together, our results demonstrate that ongoing glacier retreat at Qaamarujup Sermia not only responds to atmospheric forcing but can actively reshape the local microclimate, leading to increasingly effective melt processes. These feedbacks are critical for understanding future mass-balance evolution of glaciers in a changing climate.
How to cite: Schalamon, F. R., Scher, S., Trügler, A., Schöner, W., and Abermann, J.: Centennial Changes in Microclimate and Surface Mass Balance: A West Greenland Case Study, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18685, https://doi.org/10.5194/egusphere-egu26-18685, 2026.
In recent years a number of record-breaking, even record shattering, extreme weather and climate events have occurred over Antarctica. Such events can drive increased surface melt, thinning and even break-up of Antarctica’s ice shelves. They also pose threats to Antarctic species, ecosystems and the globally important services they provide. However, our knowledge and understanding of how extreme events over Antarctica may respond under climate forcing is lacking. To addresses this gap, the ExtAnt project is an ambitious four-year programme of research that brings together leading UK and international scientists to use new modelling resources and methods to elucidate drivers of extreme events in Antarctica. It aims to provide a comprehensive assessment of present day and future high impact extreme weather events in Antarctica, and associated risks. Key foci for impacts are surface melt on ice shelves and the highly specialised Antarctic biodiversity.
Recent science highlights will be presented on characteristics and drivers of extreme events and a new database of Antarctic extremes. An example of current early initial analysis relates to large ensembles, which shows that global climate models exhibit larger biases in mid-tropospheric daily meridional wind extremes at 65°S in summer (too weak) than in winter, in contrast to larger winter biases in the mean climatology. There is a fairly small, but clear, increase in the magnitude of meridional wind extremes in summer in the ozone hole period compared with the pre-ozone period. Wider implications the results so far will be discussed along with future plans for the project in downscaling (using both machine learning and traditional approaches), event attribution and surface melt modelling.
How to cite: Bracegirdle, T., Buzzard, S., Dow, W., Feltham, D., Fučkar, N., Kirchgaessner, A., Lu, H., Maycock, A., Orr, A., Shannon, S., Sharma, S., Widmann, M., and Williams, R.: Drivers and Impacts of Extreme Weather Events in Antarctica: Recent Results and Future Plans of the ExtAnt Project, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17631, https://doi.org/10.5194/egusphere-egu26-17631, 2026.
Polar lows (PLs) are intense small-scale cyclones whose detection remains challenging, limiting our understanding of their climatology. This study addresses this gap by developing an objective tracking algorithm to create a 35-year (1990-2024) climatology of potential PLs for the Southern Ross Sea using high resolution ERA5 reanalysis.
The method employs a multi-scale filtering approach to identify the key dynamical drivers and characteristic signatures of mesocyclogenesis. Potential systems are first detected using a primary dynamical criterion, defined by a significant maximum in 850-hPa relative vorticity, typically associated with an upper-level trough. Candidates are then filtered using a deep static instability criterion representing the thermodynamic contribution. The final selection retains features that exhibit canonical mesoscale characteristics of mesocyclones, including a compact vortex size, a short lifetime, strong surface winds, and a distinct negative mean sea level pressure (MSLP) anomaly. The results reveal that the primary regions for potential PL formation are concentrated along the Transantarctic Mountain coastline, with key hotspots near Terra Nova Bay, the Byrd Glacier and Siple Coast. The seasonal cycle is dominated by peaks in the transitional months of March and October, which represent the highest frequency of polar low candidates annually. A secondary, less pronounced peak in activity is observed during the mid-winter months of June and July. On an interannual scale, the climatology reveals a significant negative trend in summer PLs from 2008 to 2018. This decreasing trend is strongly correlated with a concurrent decline in regional atmospheric static instability, suggesting that a stabilization of the lower troposphere is a key driver of potential decline in PL number occurrence in the Ross Sea region. A key limitation of this vorticity-based approach is the potential for false positives, particularly the detection of shear-induced vorticity features that lack a coherent surface circulation. This work creates the comprehensive, long-term, and objective climatology of mesocyclogenesis for the Ross Sea Region. This foundational dataset enables a quantitative analysis of the key drivers of mesocyclogenesis in the region. It provides a crucial benchmark for systematically investigating the interaction between large-scale atmospheric patterns, katabatic wind surges, sea ice extent, and topography in forcing high-latitude PLs activity, and for assessing how these relationships may shift under future climate change.
How to cite: Hassani, S., Katurji, M., Zawar-Reza, P., Malyarenko, A., and Gossart, A.: A Vorticity-Based Climatology of Mesocyclogenesis Hotspots in the Southern Ross Sea, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8363, https://doi.org/10.5194/egusphere-egu26-8363, 2026.
Antarctic sea ice and its snow cover play a pivotal role in regulating the global climate system through feedback on both the atmospheric and the oceanic circulations. Understanding the intricate interplay between atmospheric dynamics, mixed-layer properties, and sea ice is essential for accurate future climate change estimates. This study investigates the mechanisms behind the observed sea-ice and snow characteristics at a coastal site in East Antarctica using in situ measurements in winter–spring 2022. The observed sea-ice thickness peaks at 1.16 m in mid–late October and drops to 0.06 m at the end of November, following the seasonal solar cycle. On the other hand, the snow thickness variability is impacted by atmospheric forcing, with significant contributions from precipitation, Foehn effects, blowing snow, and episodic warm and moist air intrusions, which can lead to changes of up to 0.08 m within a day for a field that is in the range of 0.02–0.18 m during July–November 2022. A high-resolution simulation with the Polar Weather Research and Forecasting model for the 14 July atmospheric river (AR), the only AR that occurred during the study period, reveals the presence of AR rapids and highlights the effects of katabatic winds from the Antarctic Plateau in slowing down the low-latitude air masses as they approach the Antarctic coastline. The resulting convergence of the two airflows, with meridional wind speeds in excess of 45 m s−1, leads to precipitation rates above 3 mm h−1 around coastal Antarctica. The unsteady wind field in response to the passage of a deep low-pressure system with a central pressure that dropped to 931 hPa triggers satellite-derived pack ice drift speeds in excess of 60 km d−1 and promotes the opening up of a polynya in the Southern Ocean around 64° S, 45° E from 14 to 22 July. Our findings contribute to a better understanding of the complex interactions within the Antarctic climate system, providing valuable insights for climate modeling and future projections.
How to cite: Fonseca, R., Francis, D., Nelli, N., Heil, P., Wille, J., Gorodetskaya, I., and Massom, R.: Drivers of observed winter–spring sea-ice and snow thickness at a coastal site in East Antarctica, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3486, https://doi.org/10.5194/egusphere-egu26-3486, 2026.
Earth system models (ESMs) often exchange solar fluxes and albedos between components using only two spectral bands (visible (VIS) and near-infrared (NIR)). In an effort to predict the albedo of cryospheric surfaces, which varies significantly through the NIR region, models often attempt to repartition these spectrally coarse incident solar fluxes into higher resolutions using prescribed, time-invariant weights. Here, we increase the resolution of solar fluxes and albedos exchanged between the atmosphere and snow-covered land surfaces within a fully coupled ESM from two bands to eight (one VIS and seven NIR bands). The exchange of higher resolution solar fluxes at the surface allows the surface models to dynamically weight the mean NIR albedo in response to time-varying atmospheric conditions. Diagnostic experiments within a fully coupled ESM show that the induced forcing on surface absorption caused by using the dynamic high resolution NIR insolation rather than prescribed weights ranges between -1.90-4.73 Wm-2. This forcing is strongly modulated by atmospheric humidity, as the presence of water vapor absorbs NIR radiation, thus changing the spectral distribution of NIR radiation at the surface, which cannot be captured with fixed weights. We find low/high humidity generally increases/reduces surface absorption. Regional climate responses over snow-covered surfaces are consistent with the applied forcing both in sign and magnitude. Replacing the coarse two-band surface albedo with an eight-band albedo better captures the steep drop of snow reflectance at longer NIR wavelengths, reducing the solar warming rate in the lower atmosphere. These advances provide a foundation for implementing a high resolution, spectrally consistent coupling of solar radiative fluxes across components within ESMs, demonstrating that increasing the spectral resolution of radiative processes yields a more physically realistic representation of albedo, surface absorption, and atmospheric absorption.
How to cite: Tolento, J., Zender, C., Roberts, A., Thomas, E., and Flanner, M.: Impacts of High-Resolution Coupling of Solar Radiation Between Atmospheric and Cryospheric Components in Earth System Models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13334, https://doi.org/10.5194/egusphere-egu26-13334, 2026.
Atmospheric rivers (ARs) represent the main intrusions of moisture and heat into Antarctica, exerting a major influence on the continent’s surface mass balance. Yet, due to geometric and directional constraints, existing detection algorithms often fail to track their evolution inland after landfall or in regions where abrupt directional changes occur. We introduce DARK (Detecting ARs using their Kurvature), a new Antarctic AR detection framework designed to overcome these limitations. DARK applies a strict 98th-percentile threshold to total integrated vapor transport and computes AR length along the curved axis to evaluate the 2000-km AR criterion. This enables the continuous detection of ARs with complex geometries, including those that curve, overturn, or extend across the South Pole. An additional AR-children module identifies smaller but still intense moisture remnants that detach from parent ARs after landfall yet continue to transport vapor and heat inland. The resulting climatology shows that DARK ARs account for about 18 % of total Antarctic precipitation and are linked to roughly half of top 1 % daily precipitation anomalies, 60 % of top 1 % daily maximum temperature anomalies, and 80 % of compound warm-and-wet events. DARK provides a more detailed assessment of AR-related precipitation and temperature impacts in the South Pole region. Despite slightly higher occurrence, risk-ratio analysis shows that DARK ARs more effectively capture the most intense events than earlier Antarctic schemes. Including AR-children further strengthens these associations, especially over Victoria Land, where they contribute to about one-third of AR-related precipitation.
How to cite: Buffet, V., Pohl, B., Favier, V., and Wille, J.: Curved atmospheric rivers and their moisture remnants: a new detection tool for Antarctica, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12591, https://doi.org/10.5194/egusphere-egu26-12591, 2026.
Antarctica experienced a rapid decline in sea ice extent in 2016 following a modest increase in annual sea ice extent. Rapid changes in Antarctic sea ice have consequences for the Antarctic climate system; however, the coupled atmosphere-ocean-ice processes driving these changes remain poorly understood. Precipitation is a key atmospheric variable influencing both the surface mass balance of the Antarctic ice sheet and the formation and persistence of Antarctic sea ice. Two major moisture sources contribute to precipitation: local evaporation due to the reduced insulation effect of sea ice and poleward moisture transport from lower latitudes, often associated with atmospheric rivers (ARs) – long, narrow corridors that transport large amounts of heat and moisture from the mid-latitudes to the polar regions.
Despite their rarity, ARs play an important role in the Antarctic climate system, contributing to surface melt on the West Antarctic Ice Sheet and extreme precipitation events across East Antarctica. However, the role of ARs and AR-related precipitation, particularly in relation to Antarctic sea ice, has been less explored.
Here, we analyze ERA5 reanalysis data to investigate the contribution of ARs to precipitation over the Southern Ocean (60 – 90S), distinguishing between different surface characteristics (open ocean and sea ice) and precipitation phase (rain and snow). Our results show that ARs contribute more to rainfall (50%) than snowfall (25%). AR-related snowfall is relatively evenly distributed across the entire study region, whereas around 75% of AR-related rainfall occurs over the Ross Sea and Amundsen-Bellingshausen Seas. While AR-related snowfall exhibits weak seasonal variability, AR-related rainfall is more pronounced in winter and spring. Regarding different surface types, AR-related rainfall primarily occurs over the open ocean throughout the year but extends over sea ice during winter. In contrast, AR-related snowfall shifts seasonally, dominating over the open ocean in summer and autumn and over sea ice in winter and spring.
Area-normalized precipitation reveals that AR-related precipitation events are more intense than non-AR events, with higher intensities in winter compared to summer. These findings highlight the important role of ARs and their potential changes in Antarctica. Finally, we compare these results with simulations from the newly developed climate model ICON-XPP to assess its ability to represent AR characteristics over the Southern Ocean.
How to cite: Lauer, M., Horvat, C., McCrystall, M., and Possner Lowdon, A.: Climatology of Atmospheric Rivers-related precipitation over different surface types in the Southern Ocean, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16196, https://doi.org/10.5194/egusphere-egu26-16196, 2026.
While persistent snow cover traditionally preserves high surface albedo and buffers against early glacier melt, shifting precipitation regimes and light-absorbing aerosols are disrupting this protective mechanism. MODIS data indicates that the pre-monsoon snow season in the North Western Himalayas (NWH) extended by 7±3 days between 2000 and 2020. This extension is driven by large-scale dynamics, specifically moisture convergence and a deepened geopotential trough at 200 hPa.Crucially, snowfall resulting from these conditions enhances the wet deposition of atmospheric aerosols. As these aerosols resurface, they diminish the albedo benefits of fresh snow by 20%. This establishes a critical feedback loop wherein increased snowfall paradoxically facilitates surface darkening and accelerates melt. This snow-aerosol interaction necessitates a revision of surface energy balance models to accurately project future regional water availability.
How to cite: Zargar, S. A., Sarangi, C., Bhariti, P., Deb, P., Banerjee, A., and Rittger, K.: Evidence of Increasing trend of snow cover in himalayas implicate snow darkening, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13762, https://doi.org/10.5194/egusphere-egu26-13762, 2026.
Snowmelt from the Andes is the primary source of freshwater for central Chile, a region experiencing prolonged drought and increasing anthropogenic pressures. Light-absorbing particles (LAPs), such as black carbon (BC) from mining vehicles and locally derived mineral dust (MD), accelerate snowmelt by reducing surface albedo. This study presents experimental results from a field campaign conducted on 27 August 2025 near Laguna del Maule, where controlled deposits of BC and MD were applied to the snow surface to quantify their impact on spectral albedo. BC (simulating mining truck emissions) and MD (local soil) were deposited cumulatively at masses of 1, 2, 3, 5, and 7 grams over a defined snow area. Surface albedo was measured using a spectroradiometric system consisting of six synchronized spectroradiometers covering 300–2500 nm. For each contamination level, 12 replicate measurements were taken. Broadband albedo (300–2500 nm) was averaged across replicates to evaluate the reduction induced by each LAP type. Due to wind-driven dispersion, the average effective mass deposited on the snow surface was 58% of the applied BC and 93% of the applied MD. Results show a consistent decrease in average broadband albedo with increasing deposition mass. A linear regression between broadband albedo and the effective surface concentration (accounting for wind loss) yielded an average albedo reduction slope of 0.014 ± 0.002 per gram of BC and 0.011 ± 0.001 per gram of MD. This indicates that, under these experimental conditions, BC exerts a stronger per-mass darkening effect than MD. These findings demonstrate that vehicular BC and wind-blown MD from mining and disturbed soils can significantly darken snow surfaces, thereby enhancing melt rates. In a region already affected by megadrought and shrinking snowpack, such albedo reductions threaten to further diminish freshwater availability. This study emphasizes the need to integrate local aerosol emissions—particularly from mining and transport activities—into hydrological and climate models for the Central Andes. The authors acknowledge the support of the National Research and Development Agency of Chile (ANID), namely, ANID-FONDECYT 3230555, ANID-FONDECYT 11220482, ANID-FONDECYT 11220525, ANID Vinculación Internacional FOVI240088, and ANID FONDEQUIP EQM250078, as well as the Multidisciplinary Research Project PI_M_24_03 from Universidad Técnica Federico Santa Maria (Chile). The spectroradiometric system was funded by the Spanish Ministry of Science and Innovation through the Acquisition of Scientific-Technique Equipment (2019) grant (ref. EQC2019-006105-P).
How to cite: Bolaño-Ortiz, T. R., McCracken, F., Ruggeri, M. F., Castro, L., González-Faune, L. A., Neira Román, J. A., Tovar-Bernal, F. A., and Lapuerta, M.: Experimental Reduction of Snow Surface Albedo by Local Black Carbon and Mineral Dust Deposition in the Andes of Laguna del Maule, Chile, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17638, https://doi.org/10.5194/egusphere-egu26-17638, 2026.
Posters on site: Tue, 5 May, 10:45–12:30 | Hall X5
Dust storms are driven by land-atmosphere interaction that transport dust and sand particles over vast distances. Dust storms have far-reaching impacts on air quality, ecosystems and human health, that affect hundreds of millions of people worldwide each year. Recognizing the importance of mitigating dust storm events and impacts, the United Nations has declared 2025-2034 as the Decade on Combating Sand and Dust Storms. However, a comprehensive understanding of the global distribution, seasonality, and land-surface controls of dust storm events remains limited, largely due to the lack of consistent ground-based, long-term, globally measured datasets.
NASA’s Atmospheric Infrared Sounder (AIRS) satellite provides a valuable global record of dust indicators, and analyzing these data enables large-scale tracking of where dust storm events occur and how their intensity evolves over time. In this study we analyze monthly dust storm data of AIRS satellite from 2003 to 2023 to show the global spatiotemporal trends in dust storms. In addition to mapping the spatial and temporal distribution of these events, we estimate the population affected by dust storms each year and assessed the intensity and frequency of these events across different land cover types. The study enables a better understanding of the regions and populations most at risk and provides valuable insights for policymakers and planners to develop strategies for mitigating the impacts of dust storms on human health, agriculture, and infrastructure.
How to cite: Soleimani, Y., Dashtian, H., AghaKouchak, A., Madani, K., and Shokri, N.: Spatio-temporal patterns of dust storms and population exposure across land use and land cover types, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1447, https://doi.org/10.5194/egusphere-egu26-1447, 2026.
Snow cover can significantly influence climate via modulating surface energy balance, yet its cross-seasonal impacts on Arctic temperatures remain poorly understood. Here, based on diagnostic analysis and numerical experiments, we reveal a robust linkage between reduced early spring (March-April) snow water equivalent (SWE) in northern Europe and increased May-June-July (MJJ) 2m air temperature over the East Siberian-Chukchi Sea during 1951–2022. Specifically, March-April SWE negative anomaly can persist to June and result in drier surface conditions due to reduced snowmelt. It led to elevated turbulent heat fluxes and positive geopotential height anomalies over northern Europe via snow-albedo and snow-hydrological effects during April-May-June. Hence, the eastward-propagating wave train enhanced over northern Europe and reaches South Siberia, causing cyclonic activity and enhanced precipitation. The resultant soil moisture increases persist into MJJ, favoring less sensible heat fluxes, upward wave activity flux, and wave train poleward-propagation. Finally, an anticyclonic anomaly appears over East Siberian-Chukchi Sea, enhancing anomalous descending motion, water vapor and downward longwave radiation, collectively raising near-surface temperatures. Moreover, numerical experiments successfully reproduce this cascade of mechanisms, confirming the physical pathway. Our study provides a new perspective for the studies of the snow cover climate effect, especially its impacts to the Arctic temperature variability.
How to cite: Wei, Z. and Ma, L.: Mechanism of Cross-Seasonal Response of Arctic Temperature to Eurasian Early Spring Snow Loss: The Critical Roles of Soil Moisture and Stationary Wave Propagation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2661, https://doi.org/10.5194/egusphere-egu26-2661, 2026.
The relationship between El Niño-Southern Oscillation (ENSO) and Southern Annular Mode (SAM) during austral summer is examined. It is found that their relationship is nonstationary and depends on the phase of the Interdecadal Pacific Oscillation (IPO). A strong ENSO-SAM relationship is observed during the positive IPO phase, while this relationship is weak during the negative IPO phase. The effects of sea surface temperature anomalies (SSTA) in the equatorial central-eastern Pacific, atmospheric stationary wave train, and synoptic-scale high-frequency eddies are found to be responsible for this interdecadal change in ENSO-SAM relationship. During the positive IPO phase, warm SSTA in the equatorial eastern Pacific associated with El Niño events induce a poleward-propagating wave train and cause an anomalous anticyclone over Antarctica. The anomalous baroclinicity to the north of the anomalous anticyclone is conducive to the eastward extension of eddy activity within the entrance of the mid-latitude jet stream, resulting in the development and maintenance of the negative SAM phase. However, during the negative IPO phases, the tropical SSTA centers during ENSO events shift towards the equatorial central Pacific, forcing the Rossby wave train that generates an anomalous anticyclone over the Ross-Amundsen Sea, to the north of that caused by ENSO during the positive IPO phase. Consequently, the anomalous baroclinicity does not align with the mid-latitude jet stream core, and the eddy-mean flow interaction at the jet stream cannot be effectively triggered, inducing a meridionally arched pattern confined to the Pacific-South American sector. Additionally, when the IPO and ENSO are out of phase (in phase), the superposition effect tends to amplify (dampen) the ENSO-SAM connection.
How to cite: Cai, X., Zhang, R., and Tan, Y.: Modulation of Interdecadal Pacific Oscillation on the Relationship Between El Niño-Southern Oscillation and Southern Annular Mode during Austral Summer, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9116, https://doi.org/10.5194/egusphere-egu26-9116, 2026.
It was recently demonstrated using an ensemble of seasonal hindcasts with the “UNprecedented Simulated Extremes using ENsembles” (UNSEEN) technique that most of the Antarctic continent could experience record-breaking heat in both January and August. Here this analysis is continued, through the investigation of the role of large-scale modes of variability with known teleconnections to Antarctica, namely the Southern Annular Mode (SAM) and the El Niño-Southern Oscillation (ENSO), towards bringing relative warmth to Antarctica and its ice shelves during these months. The relationship between 2-metre temperature (T2m) and the SAM in the UNSEEN ensemble is consistent with the observed correlations: predominantly negative in both January and August. This negative correlation is strongest in magnitude along the coast of East Antarctica, while in the extreme north of the Peninsula a weaker positive correlation emerges. January correlations between T2m and ENSO are mostly positive in both observations and the UNSEEN ensemble, but spatial disparity between the two arises in August and perhaps suggests that the phase of ENSO could have a more varied influence on heatwave occurrence on different parts of the continent.
The polarity of the SAM dominates the Antarctic-wide mid-level circulation, and the teleconnection of ENSO is superimposed on top of this through modulation of the Amundsen Sea Low. This behaviour is identified in both observations and the UNSEEN ensemble. Therefore, for much of the continent heatwave days are dominated by negative SAM (SAM-) and are often combined with El Niño (EN) conditions. For example, SAM- patterns are more than twice as common during Antarctic-wide heatwave days than during all other days, and the combination of SAM- and EN is the most prevalent pattern that leads to heatwave days in the UNSEEN ensemble. However, in some locations (notably on ice shelves along the Peninsula) the relative occurrence of SAM- is no different between all days and heatwave days, and heatwaves occur with approximately equal probability across all combinations of SAM and ENSO phases. Strikingly, unprecedented T2m in Antarctica does not result from unprecedented SAM or ENSO values, suggesting either a deficiency in the UNSEEN ensemble, or that other processes not considered in this work are responsible for the most exceptional heatwaves in Antarctica. Further investigation into the large-scale drivers of unprecedented heat days in Antarctica is therefore required.
How to cite: Suitters, C., Screen, J., Catto, J., Jones, J., and Li, S.: The Role of the Southern Annular Mode and the El Niño-Southern Oscillation on Extreme and Unprecedented Antarctic Heat, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10119, https://doi.org/10.5194/egusphere-egu26-10119, 2026.
Sea ice acts as a dynamic membrane around the Antarctic continent, modulating atmosphere-ocean interactions and dampening the waves, precipitation, and heatwaves associated with poleward-propagating storms. In May 2025, intense wind and waves from an atmospheric river family wrought destruction on the Amundsen-Bellingshausen sea ice margin, leading to major sea ice retreat at the time of year typically marked by sea ice growth, and closing coastal polynyas.
In this study, we examine the linkages between anomalous atmospheric forcing and storm structure in May 2025, associated with the atmospheric rivers, and the resultant ocean response and sea ice retreat in the Amundsen Sea. First, we use ERA5 atmospheric reanalysis and satellite observations to classify the large-scale atmospheric drivers of the initial mid-May event and subsequent month-long marine intrusion conditions, including successive Rossby waves breaking and the buildup of a blocking high over the Antarctic Peninsula. Then, using the 1.5km resolution version of the atmosphere-only UK Met Office Unified Model (with sophisticated microphysics CASIM), we dynamically downscale ERA5 to examine the detailed vertical and spatial characteristics of the storm at the sea ice margin, including winds, air temperature, clouds, and rainfall and snowfall on sea ice. Finally, we examine the downstream, lasting impacts of the storm on sea ice, polynyas, and ocean temperature in the Amundsen Sea using a regional configuration of the Massachusetts Institute of Technology general circulation model (MITgcm) and satellite observations of sea ice concentration and drift.
Ultimately, after a monotonic decrease in extent from mid-May until mid-June, sea ice extent in the Amundsen-Bellingshausen sector never recovered in 2025. Our results suggest that individual atmospheric events can produce compounding impacts on the ocean and sea ice of the Amundsen Sea Embayment.
How to cite: Maclennan, M., Haigh, M., Holmes, C., Orr, A., Gumber, S., Tang, H., LaChat, G., Baiman, R., Sharp, M., Holland, P., Li, S., and Jones, J.: Impacts of atmospheric rivers on major West Antarctic sea ice retreat in May 2025 , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11340, https://doi.org/10.5194/egusphere-egu26-11340, 2026.
Aeolian dust surface deposition on seasonal snowpacks strongly influences snow albedo and melt dynamics, yet the environmental drivers of dust accumulation and redistribution at metre-scale resolution remain incompletely understood. UAV-based multispectral imagery enables detailed mapping of snow surface darkening associated with Light Absorbing Particles (LAP) such as mineral dust, offering new opportunities to investigate spatial distribution patterns in complex alpine terrain. This study examines the potential of UAV multispectral acquisitions to determine dust-on-snow spatial distribution and the relative influence of topographic factors on its variability during the seasonal evolution of the snowpack.
Data were collected in 2025 over a ~0.5 km2 alpine study basin in the Spanish Pyrenees using a MicaSense Altum multispectral sensor mounted on a DJI Matrice 300 UAV. Five UAV acquisition campaigns were conducted between initial Saharan dust deposition and snowpack melt-out. Spectral indices sensitive to snow surface darkening by LAP were computed from the UAV imagery. Additionally, from 10 to 20 distributed in situ snow surface samples were manually collected concurrently with UAV acquisition flights to determine surface LAP concentration and close-range spectral response using a hand-held hyperspectral radiometer to calibrate UAV-derived surface LAP concentration.
A suite of potential predictors to represent potential controls on surface LAP redistribution and accumulation were selected: elevation, slope, northness, topographic position index (TPI), maximum upwind slope (Sx), diurnal anisotropic heat index (DAH), snowpack depth and snowpack depth difference. Random forest (RF) models were applied independently to each acquisition date in order to assess how the relative importance of these controls evolved through time considering the different states of the dust layer in the snowpack.
The RF models generally reproduced the spatial variability of the LAP indices well, according to internal out-of-bag evaluation and the RMSE errors remained around low for days with larger LAP concentration variability. Throughout the study period, the state of the snowpack notably influenced the relative importance of the predictors to the response variable. We were able to observe days in which fresh snow partially covered the dust layer, causing predictor variables related to snow accumulation and elevation to show the highest relative importance. Subsequently, after the full surfacing of the dust layer, the largest LAP concentrations were found in concave areas, notably increasing the relative importance of TPI.
The results demonstrate the value of combining multi-temporal UAV multispectral observations with interpretable machine-learning approaches to account for the temporal sequence of dust deposition, burial, re-exposure, and melt to advance understanding of aeolian dust processes in alpine snow-covered environments.
How to cite: Domínguez Aguilar, P., Revuelto, J., Izagirre, E., Bandrés, J., Rojas Heredia, F., Ezquerro, P., and López Moreno, J. I.: Spatio-temporal variability of dust on snow: interactions with topography and snowpack dynamics observed with UAVs, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11393, https://doi.org/10.5194/egusphere-egu26-11393, 2026.
Sand and dust storms, including High Latitude Dust (HLD), were identified as a natural hazard that affects 11 of the 17 Sustainable Development Goals. HLD is a significant contributor to land degradation, severe erosion and ecosystem collapse, as documented for example in Iceland. HLD contributes to Arctic Amplification, and it was recognized as an important climate driver in Polar Regions (IPCC SROCC, 2019; AMAP, 2021). HLD has impacts on climate, such as effects on cryosphere, cloud properties, atmospheric chemistry and radiation, and marine and terrestrial environment. Main socio-economic sectors such as health protection, road safety, energy production, aviation, and land degradation, are negatively impacted by HLD (eg. severe air pollution, mortality on roads due to reduced visibility).
Many extreme events causing severe air pollution were observed and measured in Iceland, Svalbard and Antarctica. In Iceland, we measured i. tens of severe dust storms at multiple locations annually as well as long-range transport from Iceland to Scandinavia, Faroe and British Isle, and Svalbard; ii. Snow-dust storms; iii. Saharan dust plumes causing air pollution in Iceland; iv. Extreme wind erosion events of volcanic ash mixed with dust; v. dust storms during high precipitation/low wind periods; vi. Dust storms during glacial outburst floods, vii. Arctic winter dust storms during Polar Vortex conditions, and viii. Black/Organic Carbon haze from burning mosses around the eruption in Reykjanes Peninsula, transported > 300 km to Northeast Iceland. Several dust storms were measured also in Antarctic Peninsula. In Svalbard, aerosol measurements revealed high concentrations of both dust, coal dust and Black Carbon, while dirty snow evidenced the occurrences of Snow-Dust Storms, similarly to Iceland.
In-situ particulate matter data and observations from these extreme events will be presented. It is crucial to provide long-term daily aerosol measurements and dust forecasts from the remote high latitude dust regions. Additional in-situ observations around HLD sources would confirm that the background air quality is not as good as expected, and in some cases, it is worse than industrial or some urban stations, such as in Iceland during the CAMS NCP Iceland projects.
More information and activities of HLD networks can be found at the Icelandic Aerosol and Dust Association (IceDust) websites (https://ice-dust.com/, https://icedustblog.wordpress.com/publications/), UArctic Network on High Latitude Dust (https://www.uarctic.org/activities/thematic-networks/high-latitude-dust/), NORDDUST (https://ice-dust.com/projects/norddust/), and CAMS NCP Iceland (https://ice-dust.com/projects/cams-ncp-iceland/, https://atmosphere.copernicus.eu/iceland).
How to cite: Dagsson Waldhauserova, P., Meinander, O., and members, I.: Extreme events and impacts of High Latitude Dust , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14921, https://doi.org/10.5194/egusphere-egu26-14921, 2026.
The Arctic exhibits an alarming warming rate, mainly caused by increasing greenhouse gas emissions and the climate forcing effect of aerosols. To get a better understanding of the relevance of local aerosol sources and sinks in the Arctic, vertical near-surface particle, momentum and sensible heat fluxes were investigated by collecting a large eddy covariance data set including three-dimensional wind speed, temperature and particle number concentration over ice, water and mixtures thereof during the PS131 expedition of the German research icebreaker Polarstern in 2022 using a 3-axis ultrasonic anemometer (Gill Solent HS-044, Lymington, United Kingdom) and a mixing condensation particle counter (Brechtel Model 1720, Hayward, USA). Both instruments were installed on the bow crane outrigger.
To minimize the influence of the inadvertent movement of the vessel caused by waves and wind on the anemometer data, two separate motion correction approaches were tested. The first method is based on the work of Fujitani (1981) and Edson et al. (1998). It realigns the wind vector (u, v, w) recorded in the vessel coordinate system with a reference frame while also correcting for apparent winds resulting from the tilting motion and the vessel movement in the reference coordinate system itself. Alternatively, by making use of the periodicity of the vessel movement and finding the frequencies with which the vertical wind vector component w oscillates using spectral FFT analysis, affected frequencies can be replaced assuming spectral similarity of atmospheric turbulence. Thus, it is possible to remove the impact of the movement without having to rely on the measured pitch, roll and yaw angles.
Both approaches were successfully used to correct the recorded data in preparation for calculating the sensible heat and momentum fluxes. Preliminary results suggest that the choice of motion correction approach has an impact on the obtained fluxes, though a complete evaluation of the resulting data is still pending at the time of abstract submission.
This study was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation): HE5214/10-1, HE5214/11-1 and WE 2757/6-1.
How to cite: Fröhlich, F., Mathes, T., Lüchtrath, S., Oehlke, P., Siebert, H., Wehner, B., and Held, A.: Impact of Motion Correction on Momentum and Sensible Heat Fluxes over Ice and Water Measured on a Moving Vessel in the Arctic, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17359, https://doi.org/10.5194/egusphere-egu26-17359, 2026.
Understanding the role of mineral dust deposition on snow-covered surfaces is essential for improving predictions of snowmelt timing and magnitude in mountain and polar regions. This is particularly relevant given the global diversity of dust sources, such as North Africa and Central Asia, or regional sources related to human activities. While the radiative forcing of light-absorbing impurities is increasingly well documented, there is still limited understanding of how distinct mineral dust types and their associated mineralogical and geochemical compositions differently affect snowpack energy balance and melt processes. This knowledge gap persists because many models still assume a globally uniform mineralogical composition, leading to substantial uncertainties.
In this study, we present a series of controlled experiments conducted in the SubZero cold laboratories at Montana State University, using mini-lysimeters filled with snow artificially doped with varying and environmentally realistic concentrations of mineral dust samples originating from four distinct source regions (North Africa, Iceland, North America and the Middle East) under controlled environmental conditions in the cold chamber.
Our results suggest that Fe content is a key driver of the variability observed in snow darkening and melt enhancement. Dust-emitting sediments from the studied regions display distinct mineralogical compositions, with Fe contents varying 3.0 wt% in U.S. desert samples, 3.6 wt% in Moroccan dust, 5.5 wt% in mixed African dust sources, and substantially higher levels in Icelandic surface sediments, reaching up to 9.5 wt%.
Across experiments, the results show clear reductions in snow albedo, changes in specific surface area (SSA), and increases in liquid water content (LWC) and meltwater production for different dust types samples and concentrations.
The first author has an FPI predoctoral grant in the frame of MARGISNOW project (PID2021-124220OB-100) funded by the Spanish Ministry of Science and Innovation. This research received support from SNOWDUST (AEI, TED2021-130114B-I00), POSAHPI-2 (PID2022-143146OB-I00) and FRAGMENT (ERC-2017-COG, Grant agreement ID: 773051).
How to cite: Bandrés, J., Sproles, E., Pey, J., Querol, X., Pérez García-Pando, C., and López-Moreno, J. I.: Experimental assessment of different mineral dust on snow properties and melt dynamics under cold laboratory conditions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18048, https://doi.org/10.5194/egusphere-egu26-18048, 2026.
The Antarctic is a critical component of the global atmosphere-ocean-cryosphere interaction and is simultaneously one of the regions most sensitive to climate change. However, the response to climate change varies significantly across the continent. Therefore, it is crucial to understand how the Antarctic will be impacted by climate change during the 21st century.
The aim of the study is to define general features of climate change in the Antarctic based on climate indices simulated by regional climate models (RCMs). We used WCRP standard climate indices: frost days (number of days with a daily minimum temperature < 0°C), ice days (number of days with a maximum temperature < 0°C), total annual precipitation, longest consecutive wet spell (number of consecutive days with >1 mm/day), longest dry spell (number of consecutive dry days <1 mm/day), simple precipitation intensity (annual precipitation divided by wet days), intense, heavy and extreme precipitation for the daily precipitation amounts (90th, 95th and 99th percentiles respectively). Indices were computed from three RCMs (HCLIM, MAR, RACMO) under the two storylines: (1) strong sea ice decrease and weak strengthening of the southern polar vortex; (2) weak sea ice loss but strong polar vortex strengthening. Results were compared across three periods: 1986–2005 (historical), 2041–2060 (mid-century), and 2081–2100 (end-of-century). Models results and further postprocessing were performed under Horizont2020 PolarRES and OCEAN ICE Projects.
A comparison of climatic indices from historical to the end of the century reveals a significant transition toward a warmer and wetter climate. These changes are most pronounced in the coastal regions and the Antarctic Peninsula, while the high-elevation interior remains relatively stable. Dramatic reduction in 'Ice Days' particularly on the Peninsula is projected. This reduction implies a substantial increase in surface melt potential and an extended thaw season, accompanied by a corresponding—though less severe—decrease in 'Frost Days'.
Simultaneously, the models project a clear increase in total annual precipitation, primarily over the Southern Ocean and coastal zones. Precipitation characteristics also shift, exhibiting increased daily intensity and a modest decrease in the length of 'Consecutive Dry Days' over the continental interior.
Precipitation extremes (99 th percentile) are heavily concentrated along the Antarctic Peninsula and coastal West Antarctica. In regions with significant orographic enhancement, localized intensities exceed 100 mm/day, whereas the interior plateau remains much less (<10 mm/day).
Overall, both storylines illustrate a fundamental shift in the Antarctic climate during the 21st century—particularly in coastal zones—characterized by a longer, more intense melt season and hydrological cycle. These changes hold significant implications for ice shelf stability and overall ice-sheet mass balance.
How to cite: Chyhareva, A., Krakovska, S., Palamarchuk, L., Hofsteenge, M., Lambin, C., Torres Alavez, J. A., and Mottram, R.: Climate indices change during 21st century in high-resolution RCMs, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19610, https://doi.org/10.5194/egusphere-egu26-19610, 2026.
Meteorological conditions in Ny-Ålesund (NYA), Svalbard, are influenced by the large-scale atmospheric circulation patterns, such as southerly or northerly advection as well as cyclonic or anticyclonic circulation regimes. We classify the prevailing synoptic circulation into a number of recurrent circulation weather types (CWT), to quantify their influence on local atmospheric column properties and their contribution to the observed Arctic amplification in NYA.
We construct a 45+ year CWT catalogue for NYA based on hourly 850 hPa geopotential fields from ERA5 reanalysis data using a modified Jenkinson-Collison classification. This catalogue is combined with long-term observational records from the AWIPEV radiosonde programme and the Baseline Surface Radiation Network (BSRN) in NYA.
Composite analyses reveal a pronounced directional and seasonal dependence of near-surface temperature, longwave net radiation and humidity on the prevailing CWT. Trends in CWT frequency indicate an increased occurrence of southerly advection in winter and autumn, which contributes to the enhanced warming in NYA in these seasons. Conversely, a higher frequency of northerly CWT in spring is associated with the observed cooling, particularly in March.
Consequently, CWT analysis and their long-term trends quantify the influence of synoptic circulation to atmospheric conditions in NYA and contribute to the explanation of the observed seasonal changes in the Svalbard region.
This work was supported by the DFG funded Transregio-project TRR 172 “Arctic Amplification (AC)3“.
How to cite: Eisenhuth, P. and Dahlke, S.: Assessment of Circulation Weather Types around Svalbard and their Impact on the Ny-Ålesund Atmospheric Column, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22142, https://doi.org/10.5194/egusphere-egu26-22142, 2026.
Climate models have difficulties accurately representing Arctic mid-latitude linkages. This might partly be caused by surface parametrizations that are not able to accurately represent the Arctic surface conditions. As a result, large uncertainties arise in the modelling of energy exchange between the surface and the atmosphere, since sea ice surface albedo (SIA) controls the energy input in the Arctic region. The present study aims to gain insights in how the SIA parameterization scheme in the Icosahedral Nonhydrostatic (ICON) model can influence Arctic climate.
In order to identify the sources of error in the current SIA parameterization scheme, it is evaluated against Arctic observational data. The data includes both on-ice measurements to capture the SIA temporal evolution (MOSAiC), as well as airborne measurements from several flight campaigns performed within the (AC)3 project to capture a larger spatial variability. The offline evaluation, in which the SIA parametrization is isolated from the ICON model and observations are used as input for the parametrization, shows that the biggest disagreement between the scheme and the observations occurs at freezing point temperatures.
Inspired by this outcome and to better understand how SIA parametrization can control the Arctic climate, a simulation with increased SIA at freezing point temperatures is performed. With this long term, limited area, pan-arctic simulation, changes in energy exchange between surface and atmosphere are analyzed.
This work was supported by the DFG funded Transregio-project TRR 172 “Arctic Amplification (AC)3“.
How to cite: Rompelberg, J., Handorf, D., Jacobi, C., and Jäkel, E.: Effect of Increasing freezing point Sea Ice Albedo, on controlling Arctic Climate variables in ICON, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20625, https://doi.org/10.5194/egusphere-egu26-20625, 2026.
