- Targets: snow, firn, land ice, sea ice, lake ice, river ice and permafrost on Earth as well as the surfaces and interiors of Mars, Europa, Ganymede, The Moon, Titan, Venus, Small bodies, etc.
- Instruments: airborne and spaceborne sounders, altimeters, SAR and passive microwave radiometers as well as drones, GPR, ApRES, pRES and other radars.
- Acquisition and processing: hardware, passive measurements, datasets, algorithm development, etc.
- Analysis and interpretation techniques: reflectometry, interferometry, thermometry, specularity, EM simulations, inversion, etc.
- Applications: investigations in surface-, englacial, subglacial and proglacial areas, scattering interfaces, roughness, hydrology, geothermal heat flux, material properties, fabric, modelling/supporting lab work, Earth and extraterrestrial analogues/synergies, etc.
We especially encourage the participation of Early Career Researchers and those from underrepresented groups.
Orals: Fri, 8 May, 08:30–10:15 | Room 1.34
Sea ice and its snow cover play key roles in Earth's climate. Snow depth and sea ice thickness are World Meteorological Organisation-designated Essential Climate Variables, but their complexity and heterogeneity can pose a challenge for remote sensing. Satellite radar altimetry can provide data over large length and timescales, but there are uncertainties associated with the penetration and scattering of the EM radiation used in these Earth Observation approaches and hence data products. Validation from satellite, airborne and surface-based campaigns do not present a coherent set of results, leading to a lack of clarity on the physics and the way forward for remote sensing approaches.
The depth of snow on sea ice also remains a major source of uncertainty in sea ice thickness retrievals. Using the KuKa surface based, fully polarimetric dual-frequency radar instrument, deployed in multiple Arctic and Antarctic field campaigns, it has been demonstrated that using dual-polarisation techniques could provide accurate retrievals of snow depth, performing better than dual-frequency Ku- and Ka-band approaches at the surface-based scale, along with coincident sea ice freeboard estimates. We present data over Arctic and Antarctic sea ice, and Arctic tundra, demonstrating the performance of the techniques across these scenarios. Via funding from the European Space Agency's New Earth Observation Mission Ideas (NEOMI) grant, we have developed the concept through scientific readiness levels 1-3. We explore the possibility of scaling to satellite scale and future possibilities for polarimetric altimetry over the cryosphere, using modelling and considerations of upscaling of findings from surface-based campaigns, and contrast our techniques against dual-frequency approaches.
How to cite: Willatt, R., Stroeve, J., Sandells, M., Nandan, V., Selley, H., Hogg, A., Mallett, R., Baker, S., Macfarlane, A., Huang, L., Saha, M., Fallows, A., and Nab, C.: Polarimetric Synthetic Aperture Radar Altimeter (PoSARA): progress towards a new Earth Observation mission concept for snow depth and cryosphere remote sensing, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14949, https://doi.org/10.5194/egusphere-egu26-14949, 2026.
Changing climate conditions are causing significant impacts for Arctic communities and the landscapes, ecosystems and infrastructure they rely on. Rapid permafrost degradation is not uniform over space or time and there are a variety of variables contributing to the vulnerability of different infrastructure to thaw-related hazards. These include event-based changes such as heat waves, rainfall, and storm surge events, and longer term shifts such as rising sea levels, groundwater processes during thaw season, and heat transfer from construction materials. The relative influences and interactions between these controls on the rate and nature of permafrost degradation remain poorly understood.
This work leverages correlated Ground Penetrating Radar (GPR) validated with ground probing to examine the spatial changes of the depth to base of the active layer. The GPR data have been characterised into different landscape types; those with a sand/sea interface, untouched tundra, road construction, airport aprons, and made (constructed) ground. The use of GPR prevents destruction and disruption to the already vulnerable permafrost and provides continuous subsurface mapping data. Simplified 2D numerical models have been created using electromagnetic simulation software (gprMax) to parameterise the findings from the measured field data. The purpose of this is to verify the assumptions of the processed GPR data, without the need for destructive borehole testing or coring, as would have been used historically. The combination of modelling and survey data shows the impact of the different landcover types on permafrost degradation and provides the community with valuable knowledge on the impacts of distinct alterations in land use on permafrost, allowing more informed decisions on best building practices.
These findings demonstrate the impact of assumptions made in the field of GPR settings and highlight its effectiveness in detecting the permafrost to active layer interface under different conditions. When combined with the 2D model interpretations GPR surveys offers a targeted training dataset that can potentially be scaled with earth observation data, targeting specific features, settings and infrastructure that impact permafrost degradation.
How to cite: Coote, G., Warren, C., Lim, M., Lee, R., Martin, J., and Whalen, D.: Characterising the spatial variability of permafrost measurements in different landscape types at the climate impacted coastal communities in the Inuvialuit Settlement Region, Canada, using Ground Penetrating Radar , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22545, https://doi.org/10.5194/egusphere-egu26-22545, 2026.
In the western Greenland ablation zone, most meltwater is thought to drain to the bed of the ice sheet through moulins or hydrofractures, leading to surface mass loss and seasonal ice velocity variations. However, there is a growing body of work on slow and partial depth hydrofracture, which could store meltwater englacially for longer periods of time. If widespread, this process would reduce total surface mass loss from the ablation zone, delay or reduce meltwater delivery to the subglacial system, and warm the ice through latent heat release, thus modulating all aspects of glacier mass balance.
Here, we investigate a spatially extensive, non-conformal englacial volume scattering horizon observed in Operation IceBridge ice-penetrating radar data collected in the springs of 2011-2019 in the western Greenland ablation zone. The depth of this horizon coincides with thermal anomalies in borehole temperature profiles, suggesting that it may be evidence of englacial liquid water pockets. We test this hypothesis in the Sermeq Avannarleq catchment using a Mie scattering model and show that the radar reflectivity and attenuation of this horizon are most consistent with scattering from sparse, meter-scale water inclusions in a layer of macro-porous ice ~60-80 m thick. These inversion results suggest that around 0.8 m/m2 of liquid water are stored over winter in the bottoms of surface crevasses at this site. At this same site, we also show that interannual variability in the attenuation anomaly from the scattering horizon is highly correlated with the preceding summer’s melt volume, providing further evidence linking this structure to water storage. Finally, we map the extent of this scattering horizon across the western Greenland ablation zone and find extensive spatial coverage in almost every glacier catchment from 60°-77° N. Our results show that englacial water storage is likely ubiquitous in the western Greenland ablation zone and therefore may play a more important role in modulating englacial temperature, surface mass balance, and subglacial drainage than previously assumed.
How to cite: Culberg, R. and Seleen, C.: Radar Evidence for Widespread Englacial Over-Winter Water Storage in Greenland’s Ablation Zone, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2010, https://doi.org/10.5194/egusphere-egu26-2010, 2026.
The basal unit (BU) of Planum Boreum (PB) on Mars is an ice-rich sedimentary deposit between the Late Amazonian North Polar Layered Deposits (NPLD) and the Late Hesperian Vastitas Borealis interior unit. Its two subunits, rupēs and cavi, represent records of polar geologic and climatic processes across most of the Amazonian (~3.3 Ga). The cavi unit likely consists of alternating sand and ice sheet remnants of past polar caps, reflecting volatile–sedimentary interplay, while little is known about rupēs. Thanks to recent advances in radar data processing and dense coverage by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), it is now possible to reconstruct the stratigraphy and composition of the BU, and reveal the enigmatic nature of the rupēs unit.
We analyzed over 600 MARSIS profiles at 3, 4, and 5 MHz, leveraging optimized ionospheric corrections and deep penetration to map the full thickness of the BU and retrieve its frequency-dependent complex dielectric permittivity. We find that the rupēs unit spans the western half of PB and part of Olympia Planum as a continuous body beneath the cavi unit with a pole-facing upper unconformity, occupying ~191,000 km³ (~53% of BU volume). Dielectric inversions yield a real permittivity ε’ = 4.0±0.8 (consistent at all frequencies) and a frequency-dependent loss tangent tanδ = 0.017±0.006 (3 MHz) to 0.012±0.006 (5 MHz). Both components of the dielectric permittivity exhibit strong spatial heterogeneity, with values increasing toward Hyperborea Lingula (ε’ > 6, tanδ > 0.02).
These results indicate that the rupēs composition differs substantially from that of the cavi unit, with large loss tangent values indicating the presence of significant amounts of lithic materials despite the low real permittivity. Basalt alteration products with tanδ > 0.02 are required to explain the high loss tangent measurements, while their strong frequency-dependence matches the water ice imaginary permittivity behavior. We find a best match of real dielectric permittivity and loss tangent results using a mixture of 85-90% water ice and 10-15% basalt alteration products like hydrated sulfates (e.g., gypsum), clays, and ferric oxides, which are supported by spectroscopic detections at visible exposures. Rupēs lithic materials may have been transported from lower latitude sources, where aqueous alteration is more viable than at polar latitudes. However, the strong spatial heterogeneities suggest that significant localized alteration occurred in situ during the Amazonian period, perhaps facilitated by warmer high-obliquity periods predicted to occur during the last 3 Gyr. Regardless of their source, the volume of these materials corresponds to a 24 cm–thick global layer, indicating that the rupes unit constitutes a substantial sediment reservoir, not merely one of water ice. Finally, the high loss tangent measured in Hyperborea Lingula explains the lack of rupēs basal detections by SHARAD despite the relatively low thickness (i.e., 150-200 m) of the rupēs unit at that location.
How to cite: Nerozzi, S., Christoffersen, M., and Holt, J.: Unveiling the Origin and Ice vs Lithic Composition of the Mars North Polar Basal Unit with Multiband Radar Analyses, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16088, https://doi.org/10.5194/egusphere-egu26-16088, 2026.
Waveform simulators are commonly used to retrack ice surface elevations from radar altimeter observations. Most simulators apply the radar equation to estimate backscattered power, but this formulation often overlooks refraction at the snow surface. Because snow alters the propagation direction of the radar pulse, refraction modifies both the incidence angle and the geometry of the propagating wavefront.
In this study, we derived a modified radar equation for snow-covered ice surfaces that explicitly accounts for refraction. Implementing this formulation within a waveform simulator produces waveforms that are systematically dampened and broadened relative to those generated using the conventional radar equation. Two main mechanisms account for these differences: (1) changes in wavefront geometry that reduce the returned power by a factor proportional to the square of the snow's refractive index, and (2) decreased incidence angles that increase the returned power at increasing off-nadir distances.
Our results suggest that neglecting refraction in waveform-simulator-based retracking can introduce biases in track points, as the retracker may compensate for unmodeled refraction by overestimating surface roughness. These findings underscore the importance of incorporating refraction into radar altimetry forward models to achieve accurate measurements over snow-covered ice.
How to cite: Shi, H. and Tonboe, R.: A radar equation for snow-covered targets in radar altimetry, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1380, https://doi.org/10.5194/egusphere-egu26-1380, 2026.
Radar attenuation rates are required to infer basal properties, to identify subglacial water and to characterise the thermal state of ice sheets. However, existing methods of estimating attenuation rates from radar measurements only provide depth-averaged values and rely on simplifying assumptions such as spatially constant reflectivity along the bed reflector or near-constant reflectivity of internal reflection horizons (IRHs) within the ice column. Comparisons of these methods on the same radar data set clearly show that depth-averaged attenuation rate estimates are strongly method-dependent and exhibit significant biases, which hinder the full interpretation of radar data.
Here, we present a novel approach that provides improved depth-averaged attenuation rate estimates and, unlike previous works, can estimate depth-resolved attenuation rate profiles. We cast the problem of estimating attenuation rates as a Bayesian inference problem. To solve for the posterior distribution of attenuation rates underlying radar data, we first design a radar forward model that can generate realistic radar traces given depth profiles of attenuation rates. Subsequently, we apply Neural Posterior Estimation, a machine learning technique for estimating Bayesian posterior distributions, and train it on pairs of simulated radar traces and attenuation rate profiles. For synthetic radar data, our approach robustly infers both depth-averaged and depth-resolved attenuation rates and outperforms existing methods. We further demonstrate its transferability to ground-penetrating radar data collected at two distinct ice-dynamic settings in Antarctica: South Pole Lake and Rutford Ice Stream. In both cases, the temperature profiles derived from the inferred depth-resolved attenuation rates match in-situ borehole temperature measurements. This is a significant step forward in recovering englacial temperatures from ground-penetrating radar data, as well as in achieving an uncertainty-constrained interpretation of the basal reflection power.
How to cite: Muhle, L. S., Moss, G., Schlegel, R., and Drews, R.: Simulation-based inference of depth-resolved radar attenuation rates , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9941, https://doi.org/10.5194/egusphere-egu26-9941, 2026.
Ice internal thermophysical properties are key factors in the study of dynamics and thermodynamics of ice sheet. Due to the capability of microwave to penetrate ice, several studies have illustrated the feasibility of using active and passive microwave remote sensing approaches to determine the ice internal thermophysical properties, such as temperature profile of ice sheet. On one hand, based on the sensitivity difference across different frequencies to different depth, multifrequency brightness temperature can be used to retrieve ice sheet internal temperature profile. On the other hand, the radar attenuation derived by the ice penetrating radar echo is also strongly correlated with ice temperature. Thus, several studies have tried to develop combined active and passive remote sensing approaches to make better constraints of ice sheet internal temperature profile. In our recent study, a combined active and passive retrieval algorithm for ice sheet internal temperature profile has been developed and demonstrated with ultrawideband radiometer and ice penetrating radar data on Greenland, and an active and passive microwave suite named ICE Penetrating Radar and Thermal Profiler (ICEPATH) including ice penetrating radar and ultrawideband radiometer system is also developed, aiming to detect the internal structure and physical properties of ice sheets and glaciers. This naturally leads us to wonder whether such active and passive microwave remote sensing approaches can be used to make detection of ice shell internal thermophysical properties on icy moons. This study aims to explore the application of active and passive microwave remote sensing approaches on earth polar region in icy moon detection, discussing the mechanism and feasibility of using active and passive microwave remote sensing approaches to detect the ice shell internal thermophysical properties. The results are expected to provide technical basis and serve as important reference for the icy moon exploration missions, supporting the thermal evolution analysis and providing new critical evidences for the existence of subsurface ocean and habitability of icy moon.
How to cite: Bai, D. and Zhu, D.: Active and Passive Microwave Remote Sensing of Ice Internal Thermophysical Properties: from Earth Polar Region to Icy Moon, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16102, https://doi.org/10.5194/egusphere-egu26-16102, 2026.
Two large space missions, JUICE and EUROPA Clipper are on their way to reach the icy satellites of Jupiter in the early 2030s. One of the main scope of these missions is to find liquid water below/inside the icy crusts and to assess the habitability conditions of such ocean worlds. Radar sounders, on board these missions, will play a fundamental role in detecting position, depth and composition of the water. However, presently our understanding of the composition and thermal state of such icy crusts is poorly constrained, which makes the detection of liquid water using radio waves very difficult. Therefore, it is of paramount importance to perform systematic measurements of the dielectric properties of a large set of icy materials having different salt composition and temperature, to define the range of penetration of the radar signals in different scenarios and to assess the detectability limit of the water.
To reach this goal, as a first step, it is important to determine the dielectric properties of pure water ice in the frequency range typical of planetary radar sounders (1-100 MHz). The aim of this work was to optimize the laboratory procedure to assess such properties, combining X-ray micro-computed tomography images with low/high frequency dielectric measurements. The experimental activity was first focused on defining a procedure to produce polycrystalline Ih ice samples, minimizing the presence of defects like air bubbles and cracks - which are known to affect the results of the dielectric measurements. To achieve this purpose, different samples were prepared using different sample holders and cooling rates and then analysed qualitatively and quantitatively using microtomography. Once the most reliable procedure to minimize ice defects was assessed, samples of pure ice were produced in a climatic chamber simultaneously using the microtomography and the dielectric cells, to test the possibility to perform structural analysis and dielectric measurements on the same type of ice. Dielectric measurements were performed using both a capacitive cell connected to an LCR-meter instrument and a coaxial line connected to a VNA. The results of this work confirm that this procedure can be successfully applied to control the integrity of the sample and to assess, at the same time, the dielectric properties of pure Ih ice.
How to cite: Cimbolli Spagnesi, F., Cosciotti, B., Lauro, S. E., Mattei, E., and Pettinelli, E.: Preliminary tests to combine X-ray microtomography and dielectric measurements to assess the radar properties of pure water ice, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14385, https://doi.org/10.5194/egusphere-egu26-14385, 2026.
The Jovian icy moons – Ganymede, Europa, and Callisto – are of great astrobiological and geophysical interest due to the potential presence of liquid water inside/beneath their icy shells. Among all geophysical methods, Radio Echo Sounding (RES) appears to be the most suitable technique to detect such hidden water, especially as it can operate from an orbiting platform. Starting early 2030s, RIME and REASON, the radar sounders aboard JUICE and Europa Clipper missions, will extensively explore the internal structure of the Galilean moons to search for any evidence of liquid water and to help assessing the habitability conditions of such icy bodies. In order to properly interpret the radar data, the dielectric behaviour of the material composing the crust must be known. Data regarding the dielectric behaviour of salty ices are sparse, especially in the frequency range of such radar sounders, and poorly understood.
Given the ambiguity in the composition of the icy crusts, a large set of icy analogues should be explored, although laboratory measurements are time consuming and difficult to be properly performed. In this work we start addressing this problem, combining dielectric properties measured in laboratory with radar signal propagation simulations.
Because the capability of radio waves to investigate deep in the crust depends on signal attenuation that, in turn, is controlled by temperature, type of salt and salt concentration, we performed dielectric measurements at various temperatures and salt concentrations. We started by considering the most problematic salt, NaCl, as it is known to be able to enter the ice lattice and affect the conductivity of the icy mixture (and thus signal attenuation). We measured the complex dielectric permittivity of NaCl-doped ice samples over a radar frequency range of 1-100 MHz for the salt concentration range 10-1000 mM and the range of temperature 198-292 K, using a two-port Vector Network Analyzer (VNA) coupled with a coaxial cage cell inserted in a climatic chamber. Then, we used the results of such measurements to generate different subsurface scenarios and to run radar simulations at 9 MHz (one of the operational frequencies of RIME and REASON), to assess the detectability of various targets inside the icy crusts and to validate the performance of the radars.
Our results provide a first hint on the detectability of the water inside/below an NaCl-icy crust and on the penetration depth of the radar signals in different thermal and salt concentration profiles.
How to cite: Turchetti, G., Lauro, S., Pettinelli, E., Cosciotti, B., Mattei, E., and Brin, A.: Dielectric Characterization of Salty-Ice Analogues and Simulations of Radar Signal Propagation Through the Icy Crust of Jovian Moons , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14842, https://doi.org/10.5194/egusphere-egu26-14842, 2026.
Posters on site: Wed, 6 May, 14:00–15:45 | Hall X5
Satellite remote sensing is the primary way to monitor seasonal as well as long-term changes across broad portions of the Arctic. Subject to certain conditions (e.g., illumination), these data are collected continuously with known spatiotemporal coverage and resolution. And when supplemented with ground-based in situ calibration/validation measurements, satellite measurements can be used to infer some of the critical geophysical properties (e.g., surface elevation change, surface melting, etc.) that underpin our ability to project long-term ice sheet and ice cap evolution to in the future.
This workflow however relies on the assumption that how the actual in situ conditions affect and manifest within the satellite measurements is constant or predictable through time and space. Put another way, that the in situ measurements used in calibration and validation are 1) representative of all transient (e.g., seasonal and/or multi-annual) conditions, or 2) that we can reliably modify/correct our satellite data interpretations to account for these changes. Recent work on the Greenland Ice Sheet has started to show that this assumption may be violated during periods of extreme warming; where warming may impact the satellite measurements in one way in one region (e.g., as an increase in radar altimetry echo strength), but in a different way in another (e.g., a fall in radar altimetry echo strength). Without a fuller understanding of how melting is affecting the ice sheet near-surface, these differences directly complicate the recovery of temporally comparable long-term satellite records.
As an alternative to costly in situ calibration/validation campaigns, in this study we investigate the transient changes in the surface conditions of Arctic ice caps (i.e., Flade Isblink in Greenland, Austfonna in Svalbard and Vatnajökull in Iceland) via their impact on multiple satellite datasets. Small Arctic ice caps are useful in this regard as they often experience more variable climate forcings than remote interior portions of the Greenland Ice Sheet and therefore stronger seasonal patterns. Specifically, we are interested in developing a consistent model for how seasonal melt alters the near-surface of these ice caps by integrating Copernicus Sentinel-2 (optical), ESA CryoSat-2 (Ku-band radar altimetry), ISRO/CNES SARAL/AltiKa (Ka-band radar altimetry), Copernicus Sentinel-1 (C-band SAR), ESA SMOS (L-band passive microwave), and JAXA AMSR-2/E (multi-frequency passive microwave) satellite datasets. Our interpretation of these satellite datasets are supplemented with in situ measurements where available.
How to cite: Scanlan, K. M.: Unravelling Seasonal Changes in Arctic Ice Cap Surface Conditions through Multi-Satellite Synthesis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10425, https://doi.org/10.5194/egusphere-egu26-10425, 2026.
Surface melting and runoff account for about half of the current mass loss of the Greenland Ice Sheet. Regional climate models (RCMs) project runoff to increase further over the 21st century, but the magnitude of this trend varies strongly between different models. This variability arises because RCMs rely on simplified representations of the complex firn hydrological system in Greenland’s percolation zone. However, key parameters for parametrizing meltwater retention and runoff processes remain poorly constrained due to a lack of time-resolved, in situ observations of firn liquid water content.
We address this gap by demonstrating that the Autonomous phase-sensitive Radio-Echo Sounder (ApRES) can continuously trace the amount of liquid water in the firn. At three automatic weather station sites on the ice sheet (KAN_U, DYE-2 and Camp Century), we acquired hourly ApRES time series between spring 2023 and 2025, covering two melt seasons. By analyzing these observations in combination with a firn model, we quantify rates of lateral meltwater flow. Comparison with runoff simulations from three RCMs shows that all models overestimate local runoff at KAN_U, and that some even predict runoff at DYE-2 (2124 m a.s.l.), where our observations indicate that all meltwater is refrozen. Expanding these observations will support the development of improved representations of Greenland’s firn hydrological system in RCMs and ultimately enhance the accuracy of GrIS mass balance projections.
How to cite: Oraschewski, F. M., Vandecrux, B., Puggaard, A., Drews, R., Karlsson, N. B., Nicholls, K. W., Ahlstrøm, A. P., Tedstone, A., Machguth, H., and Rutishauser, A.: Quantifying runoff in Greenland’s percolation zone with phase-sensitive radar and firn modeling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20497, https://doi.org/10.5194/egusphere-egu26-20497, 2026.
Since its launch in 2010, CryoSat-2 has continued the long-term radar altimeter record, and provided over a decade of measurements with which to monitor and understand the polar ice sheets. Although these datasets have historically been distributed by ESA as Level-2 products, following consultations with the wider glaciological community, it has become increasingly clear that there is significant untapped value that can be realised by expanding the user-base through the development of a dedicated L2 Thematic Land Ice Product. Crucially, this requires simplified, agile and state-of-the-art products and processing flows, which are updated regularly, and deliver an easy-to-use dataset whilst maintaining the native along-track sampling of the original Level-2 products. Thus, ESA has embarked on a new path towards developing CryoSat-2 Thematic Products, which aim to drive further innovation and exploitation, and have created a model that has now been replicated across other radar altimeter missions.
Here, we present the latest Cryo-TEMPO Land Ice product. The over-arching objectives of Cryo-TEMPO are (1) to implement dedicated, state-of-the-art processing algorithms, (2) to develop agile, adaptable processing workflows, that are capable of rapid evolution and processing at high cadence, (3) to create products that are driven by, and aligned with, user needs; thereby opening up the data to new communities of non-altimetry experts, and (4) to deliver transparent and traceable uncertainties. We provide an overview of the Land Ice product, a review of the current generation of this thematic product, and look ahead to the evolutions planned for the next phase of the study.
How to cite: McMillan, M., Boxall, K., Muir, A., Di Bella, A., Scagliola, M., and Bouffard, J.: Cryo-TEMPO: a CryoSat-2 Thematic Product over Land Ice, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18760, https://doi.org/10.5194/egusphere-egu26-18760, 2026.
An inapparent landslide refers to a subsurface mass movement that develops without producing obvious surface deformation or destruction . Such landslides commonly occur within rock or soil masses that are highly susceptible to fracturing and possess inherently weak internal structures. When triggered by external factors such as rainfall, these concealed landslides can accelerate and expand rapidly, causing abrupt changes in topography and resulting in severe losses of life and property. Crucially, recent studies have identified the bedrock interface as the decisive factor for the stability analysis and early warning of such landslides. However, conventional ground-based monitoring methods provide only sparse point measurements and fail to resolve the continuous subsurface structure.
Unmanned Aerial Vehicle-based Ground-Penetrating Radar (UAV-based GPR) is an efficient and non-destructive geophysical detection technology. It generally consists of the UAV platform, a GPR subsystem, the flight control and basic positioning sensors of the UAV, high-accuracy positioning sensors, and a communications subsystem (Figure 1). Compared to conventional ground-based GPR, UAV-based GPR offers offers a promising non-contact solution for such landslides, enabling rapid and safe surveys over hazardous terrain Nevertheless, in complex mountainous environments, dense vegetation and steep, undulating topography significantly degrade data quality, leading to severe imaging artifacts and interpretation ambiguity .
In this study, we propose reverse time migration (RTM) formulated in a curvilinear coordinate system for UAV-based GPR. Subsequently, we introduce an interface extraction technique to accurately identify the continuous bedrock interface from the migration profiles. For data acquisition, we deploy a low-frequency UAV-based Stepped‑Frequency Continuous‑Wave GPR (SFCW-GPR) system in the landslide-prone regions of Sichuan Province. The system achieves effective penetration depths of up to 20 m while maintaining stable imaging quality. These results indicate that the proposed framework provides a practical and high-resolution solution for the identification and structural characterization of inapparent landslides in complex mountainous environments.
Figure 1 The UAV-based GPR system used for landslide investigation.
How to cite: Wang, W., Li, T., and Yu, N.: Deep-Penetrating UAV-GPR Imaging for Inapparent Landslide Investigation in Rugged Terrain, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16505, https://doi.org/10.5194/egusphere-egu26-16505, 2026.
The use of astronomical radio sources has been demonstrated for sounding and echo detection using quiescent solar emissions in VHF (300 MHz). Here, we present the first demonstration of using Jovian HF radio bursts (25 MHz) to detect a reflection off the hills of Dante’s View in Death Valley, California.
Solar emissions are governed by blackbody radiation, which at HF is not resolvable from the galactic background noise. In contrast, Jovian bursts are governed by the interaction of Jupiter’s magnetosphere and Io’s magnetic field, which produces a significantly stronger and detectable HF emission on Earth, Mars, and Europa. While this mechanism is not continuous, it is highly predictable, as the orbital parameters of Jupiter System III central meridian longitude and Io’s orbital phase dictate the probability of a burst occurring.
As part of the Passive Autonomy, Navigation, Topography, and Habitability Exploration Radar (PANTHER), our system setup uses an HF dipole antenna and software-defined radio (Ettus X310 TwinRX) to receive radio signals at a 25 MHz center frequency with a 20 MHz bandwidth. The expectation of the experiment was to observe the reflection of a Jovian burst from Badwater Basin, which behaves like a flat specular reflector. However, during the field demonstration, the timing of the bursts—combined with Jupiter’s elevation angle and viewing geometry from Dante’s View—did not produce a basin reflection. Instead, this experiment required a more complex geometric analysis and signal processing to determine a reflection point on the hillside of Dante’s View. We emphasize that demonstrations using Jovian bursts thus require additional geometric and timing constraints that were not required for prior passive sounding experiments using continuous quiescent solar emissions. In addition to predicting the burst windows, this technique requires selecting an antenna location that provides favorable reflection geometry.
Our results provide the first demonstration of a Jovian radio burst as an HF source for passive radar echo detection, which is the first step towards a low-resource passive HF system that uses Jovian bursts for future planetary sounding missions. Building on this first demonstration, PANTHER aims to utilize the benefits of the HF signal and its lower attenuation coefficient to sound geologic targets in Iceland including glaciers, lava flow fields, and subsurface ice deposits.
How to cite: Kristinsson, T., Peters, S., Voigt, J., Steinbrugge, G., Hamilton, C., Diniega, S., Williams, J., Alfonso, G., and Romero-Wolf, A.: PANTHER – First experimental demonstration of using Jovian radio bursts as an illuminator of opportunity for passive radar echo detection, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-879, https://doi.org/10.5194/egusphere-egu26-879, 2026.
Planetary and small-body lander missions, as well as CubeSat-based exploration platforms, require robust proximity sensing capabilities to support descent, landing, and surface operations. This contribution presents a compact, coherent dual-channel FMCW radar designed as a proximity sensor for planetary and small-body missions. The radar features a volume of less than half a CubeSat unit and operates over a wide, mission-configurable frequency range from 10 MHz to 6 GHz, allowing adaptation to antenna accommodation, platform constraints, and planetary protection or regulatory requirements. The integrated power amplifier provides a transmit power of up to 2 W, while the minimum detectable signal reaches −125 dBm. Output power and sensitivity can be further extended using external amplification stages if required.
The radar is fully software-configurable, offering flexible control over RF bandwidth, sweep duration, intermediate-frequency sampling rate, and output power. It supports up to two transmit and two fully independent, phase-coherent receive channels. Depending on the operational duty cycle, average power consumption can be as low as 2.5 W, making the system suitable for resource-constrained CubeSat and lander platforms.
Designed for autonomous operation, the system performs real-time, on-board signal processing to provide deterministic, terrain-relative proximity measurements independent of external navigation or communication infrastructure. In its primary mode, the radar functions as a radar altimeter and descent monitor, delivering continuous estimates of range to the surface and relative vertical velocity. These measurements are well suited for guidance, navigation, and control during terminal descent, landing detection, and post-landing assessment.
In secondary mode, the radar can be used as a surface analyzer and subsurface sounder. Due to its enormous bandwidth and high dynamic range, the radar can be operated as a surface analyzer to map surface permittivity and roughness and, in GPR mode, to characterize the shallow subsurface with high spatial resolution. In the low-frequency range, the instrument is capable of performing deep sounding measurements with high penetration depth to analyze the deep interior of small bodies or planetary subsurface structures.
In addition, a cooperative transponder mode enables two-way FMCW ranging between multiple mission elements, such as a lander and an accompanying CubeSat or orbiter, supporting relative navigation and formation tracking. Operating at low frequencies with link budgets of up to approximately 155 dB, this mode allows the use of simple, non-directional antennas. A low-data-rate communication mode can also be implemented on the same hardware to support beaconing and basic command and housekeeping functions during descent and surface operations.
The presented radar system is intended as mission-agnostic proximity-sensing infrastructure for planetary exploration. Owing to its coherent architecture, it is inherently compatible with advanced processing techniques, including synthetic aperture processing for surface characterization and subsurface sounding, which are identified as promising directions for future work.
How to cite: Plettemeier, D., Laabs, M., and Geißler, F.: A compact FMCW Radar as a Proximity Sensor and Subsurface Analyzer for Landers or CubeSats in Planetary or Small Body Missions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14142, https://doi.org/10.5194/egusphere-egu26-14142, 2026.
Analysis of Flash Memory [1] data acquired by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument aboard ESA’s Mars Express spacecraft, confirms the presence of additional strong subsurface reflections within the South Polar Layered Deposits, located near the northernmost extent of the previously identified subglacial water bodies [2,3].
Figure 1 shows the ground track of orbit 10786 over the topography of the Martian South Pole, where anomalous subsurface reflections have been recorded, highlighted by the blue dots.
Fig. 1. Topography Maps of the investigated area.
The ground track of orbit 10786 (Figure 2, panel a) crosses the Martian south polar region where these anomalous reflections are detected at shallow depths, occurring approximately 5μs after the surface echoes. A comparison between the observed radar signals and electromagnetic simulations of surface returns (Figure 2, panels b and d) demonstrates that these features are authentic subsurface reflections rather than lateral clutter. The analysis of surface and subsurface echo power (Figure 2, panel e) reveals that, in several signals, the subsurface echoes are significantly stronger than the corresponding surface echoes, indicating a pronounced dielectric contrast variation, between the overlying medium and the subsurface target. Constraining the dielectric properties and the nature of the subsurface material, requires further investigation. This effort will be supported by future MARSIS observations planned for August 2027 and, in particular, April 2029, when the instrument will observe the region during the deep Martian night, thus minimizing ionospheric attenuation and distortion effects.
Fig. 2. Science Investigation. a) Zoom of the topography map. b) Comparison between real and simulated data at echo level. c) Simulated Radargram. d) Real data. e) Trends of surface and subsurface echo power.
References:
[1] A. Cicchetti, et al., Observations of Phobos by the Mars Express radar MARSIS: Description of the detection techniques and preliminary results. Adv. Space Res. 60, 2289-2302 (2017).
[2] Orosei R. et al., “Radar evidence of subglacial liquid water on Mars”, 2018, Science, 361
[3] Lauro S.E. et al., “Multiple subglacial water bodies below the south pole of Mars unveiled by new MARSIS data”, 2022, Nature Astronomy
This work was supported by the Italian Space Agency (ASI) through contract 2024-40-HH.0
How to cite: Cicchetti, A., Orosei, R., Pettinelli, E., Lauro, S., Noschese, R., and Cartacci, M.: Anomalous Shallow Subsurface Radar Reflections Detected by MARSIS in the South Polar Layered Deposits, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12953, https://doi.org/10.5194/egusphere-egu26-12953, 2026.
Understanding the interior structure and lithology of asteroids is crucial for gaining insights into their origin and evolution. The European Space Agency’s (ESA) Hera and China’s Tianwen-2 asteroid missions will employ monostatic orbital radar to investigate the interiors of the target asteroids Dimorphos and 2016 HO3, respectively. While most previous studies have focused on imaging asteroid interiors using bistatic radar data, relatively few have explored the same task using monostatic radar data (MRD). To support the measurement strategy and upcoming data processing for the two missions, it is essential to investigate potential imaging methods for reconstructing asteroid interiors from MRD. In this study, we propose a three-dimensional (3D) full-waveform inversion (FWI) approach to obtain the internal structure and permittivity distribution from MRD. Numerical experiments on 3D rubble pile and onion shell asteroid models validate the feasibility and accuracy of the proposed method. Additionally, a sensitivity analysis is performed using the 3D onion shell model to assess the influence of three factors—radar measurement points, number of orbits, and distance between adjacent orbits—on the FWI results. This study offers an effective approach for imaging asteroid interiors using MRD and provides valuable insights for optimizing acquisition geometries in future asteroid missions.
How to cite: Xu, Z., Yuan, Y., Zhu, P., Zhang, F., Zheng, S., Liu, R., and Li, S.: 3D full-waveform inversion of asteroid interior from monostatic radar data and its implications for acquisition geometry optimization, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8480, https://doi.org/10.5194/egusphere-egu26-8480, 2026.
This study details preliminary work for the data processing of JuRa spaceborne planetary sounding radar which will investigate the interior of the binary S-type asteroid Didymos in 2027 as part of the ESA Hera mission [1]. Spaceborne planetary sounding radars are designed to remotely probe planetary bodies subsurface at decametric to metric resolutions at depths ranging from few hundred meters up to few kilometers depending on the carrier frequency used. These radar characteristics are driven by geophysical (e.g. penetration and spatial resolution) and technical considerations (e.g. power and antenna size). JuRa was designed as a monostatic radar with an antenna composed of two crossed 1.5m dipoles able to emit Binary Phase Shift Keying (BPSK) coded signals in a 20 MHz bandwidth centered around a 60 MHz carrier, and 5 W peak power. Such configuration allows to emit and receive with either dipole antennas allowing full polarization characterization. In order to perform 3D internal structure imaging, a sufficient diversity of geometry of acquisition is required involving multiple orbits and sounding measurements on each orbit. One of the major challenge when exploiting radar data data to reconstruct the internal structure of kilometric-size planetary bodies lies in the relatively large size of the planetary body with regard to the radar carrier signal wavelength. Accordingly, processing JuRa downlinked data using Full Waveform Inversion (FWI) to reconstruct the internal structure of Didymos (800m diameter) and its moon Dimorphos (160m diameter) will prove a computationally challenging task given the relatively short radar carrier signal wavelength (~5m). In order to overcome this limitation, we investigate the possibility to use gradient descent algorithms with a linearized forward operator to process data from spaceborne planetary sounding radar dedicated to asteroid interior imaging. Performances of the proposed internal structure imaging algorithm are evaluated on a previously published asteroid analog anechoic chamber dataset [2] using Discrete Dipole Approximation to compute electric fields. Results showcase the ability to recover main interior structures in the analog case opening promising perspectives for JuRa data processing and for future asteroid interior sounding radars.
[1] P. Michel, M. Küppers, A. C. Bagatin, B. Carry, S. Charnoz, J. De Leon, A. Fitzsimmons, P. Gordo, S. F. Green, A. Hérique, et al., “The esa Hera mission: detailed characterization of the Dart impact outcome and of the binary asteroid (65803) Didymos,” The planetary science journal, vol. 3, no. 7, p. 160, 2022.
[2] A. Dufaure, C. Eyraud, L.-I. Sorsa, Y. Yusuf, S. Pursiainen, and J.-M. Geffrin, “Imaging of the internal structure of an asteroid analogue from quasi-monostatic microwave measurement data – I. the frequency domain approach,” Astronomy & Astrophysics, vol. 674, p. A72, 2023.
How to cite: Berquin, Y., Hérique, A., Rogez, Y., Kofman, W., and Zine, S.: Performance assessment of JuRa internal structure imaging of Didymos using gradient descent algorithms with a linearized forward operator, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17069, https://doi.org/10.5194/egusphere-egu26-17069, 2026.
Posters virtual: Tue, 5 May, 14:00–18:00 | vPoster spot 1a
EGU26-21809 | ECS | Posters virtual | VPS20
D-PERSEUS: A Drone Radar Mission to Study a Debris-Covered Glacier on MarsTue, 05 May, 14:18–14:21 (CEST) vPoster spot 1a
Near-surface water ice in Phlegra Montes, Mars, could support human exploration and settlement. Orbital sounding radar provides strong evidence for the existence of this ice, as does morphology consistent with debris-covered glaciers. Impact excavation of these glacier-like features has exposed ice, visible in HiRISE images, but the distribution and quantity of this ice is uncertain, necessitating further evaluation for its potential to support human exploration. We are developing the Prototype Radar Sounding Experiment for Unveiling the Subsurface (PERSEUS) instrument to study debris-covered glaciers on Earth and Mars, and we propose D-PERSEUS, a mission to study a debris-covered glacier in Phlegra Montes using a drone-based Ground Penetrating Radar like this one. This mission could verify the presence of water ice in-situ and improve characterization of water ice resources, which could serve as exploratory work ahead of a potential Mars Life Explorer mission.
How to cite: Spurling, R., Nerozzi, S., and Aguilar, R.: D-PERSEUS: A Drone Radar Mission to Study a Debris-Covered Glacier on Mars, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21809, https://doi.org/10.5194/egusphere-egu26-21809, 2026.
