Articles | Volume 19, issue 5
https://doi.org/10.5194/tc-19-1937-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-19-1937-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
A facet-based numerical model to retrieve ice sheet topography from Sentinel-3 altimetry
Jérémie Aublanc
CORRESPONDING AUTHOR
Collecte Localisation Satellites (CLS), Ramonville-Saint-Agne, France
François Boy
Centre National d’Études Spatiales (CNES), Toulouse, France
Franck Borde
ESA/ESTEC, Noordwijk, the Netherlands
Pierre Féménias
ESA/ESRIN, Frascati, Italy
Related authors
Ghislain Picard, Justin Murfitt, Elena Zakharova, Pierre Zeiger, Laurent Arnaud, Jeremie Aublanc, Jack C. Landy, Michele Scagliola, and Claude Duguay
EGUsphere, https://doi.org/10.5194/egusphere-2025-6056, https://doi.org/10.5194/egusphere-2025-6056, 2026
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
Short summary
Short summary
Radar altimeters measure ice-sheet elevation and sea-ice thickness. To improve their accuracy, we developed a model that simulates altimeter waveforms based on the physical properties of snow and sea ice. It computes the power, time, and Doppler shift of radar echoes as waves travel to the surface, interact with snow and ice, and return to the satellite. The model was verified internally, validated against other models and applied in Antarctica using in-situ snow measurements.
Maya Raghunath Suryawanshi, Malcolm McMillan, Jennifer Maddalena, Fanny Piras, Jérémie Aublanc, Jean-Alexis Daguzé, Clara Grau, and Qi Huang
The Cryosphere, 19, 2855–2880, https://doi.org/10.5194/tc-19-2855-2025, https://doi.org/10.5194/tc-19-2855-2025, 2025
Short summary
Short summary
Increasing melting rates of the polar ice sheets are contributing more and more to sea level rise. Due to the remoteness and expanse of ice sheets, these changes are mainly observed using satellites. However, the accuracy of these measurements depends on the processing of these datasets. Here we use advanced algorithms to provide improved historical ice sheet elevation measurements, derived from satellite altimeters flying between 1991 and 2012, which will benefit cryospheric applications.
Ghislain Picard, Justin Murfitt, Elena Zakharova, Pierre Zeiger, Laurent Arnaud, Jeremie Aublanc, Jack C. Landy, Michele Scagliola, and Claude Duguay
EGUsphere, https://doi.org/10.5194/egusphere-2025-6056, https://doi.org/10.5194/egusphere-2025-6056, 2026
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
Short summary
Short summary
Radar altimeters measure ice-sheet elevation and sea-ice thickness. To improve their accuracy, we developed a model that simulates altimeter waveforms based on the physical properties of snow and sea ice. It computes the power, time, and Doppler shift of radar echoes as waves travel to the surface, interact with snow and ice, and return to the satellite. The model was verified internally, validated against other models and applied in Antarctica using in-situ snow measurements.
Noémie Lalau, Michaël Ablain, Thomas Vaujour, François Boy, Gerald Dibarboure, and Alejandro Egido
EGUsphere, https://doi.org/10.5194/egusphere-2025-6364, https://doi.org/10.5194/egusphere-2025-6364, 2026
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
We investigated how to maintain continuous sea level measurements between current Sentinel-3 satellites and the upcoming Sentinel-3 Next Generation Topography mission. Because of new satellite designs, a 4-hour delay will exists between observations during the calibration phase. By simulating this lag, we found that, despite increased uncertainty, reliable calibration is possible. Extending this phase to one year ensures a stable, long-term record for climate and ocean monitoring.
Maya Raghunath Suryawanshi, Malcolm McMillan, Jennifer Maddalena, Fanny Piras, Jérémie Aublanc, Jean-Alexis Daguzé, Clara Grau, and Qi Huang
The Cryosphere, 19, 2855–2880, https://doi.org/10.5194/tc-19-2855-2025, https://doi.org/10.5194/tc-19-2855-2025, 2025
Short summary
Short summary
Increasing melting rates of the polar ice sheets are contributing more and more to sea level rise. Due to the remoteness and expanse of ice sheets, these changes are mainly observed using satellites. However, the accuracy of these measurements depends on the processing of these datasets. Here we use advanced algorithms to provide improved historical ice sheet elevation measurements, derived from satellite altimeters flying between 1991 and 2012, which will benefit cryospheric applications.
Rémi Jugier, Michaël Ablain, Robin Fraudeau, Adrien Guerou, and Pierre Féménias
Ocean Sci., 18, 1263–1274, https://doi.org/10.5194/os-18-1263-2022, https://doi.org/10.5194/os-18-1263-2022, 2022
Short summary
Short summary
To ensure that the sea level is measured as accurately as possible by satellite altimeters, we must monitor possible sea level drifts caused by those instruments through comparison with other satellite altimeters or tide gauges. In this paper, we describe a method and estimate the associated uncertainties for detecting altimeter drifts over short time periods (from 2 to 10 years) through cross-comparison with other satellite altimeters and apply it to the recent Sentinel-3 A/B altimeters.
Cited articles
Aublanc, J.: Sentinel-3 AMPLI Ice Sheet Elevation, Version 1, ESA Open Science Catalog [data set], https://doi.org/10.57780/s3d-83ad619, 2025a.
Aublanc, J.: Sentinel-3 AMPLI User Handbook, Issue 1.0, https://eoresults.esa.int/d/sentinel3-ampli-ice-sheet-elevation/2025/05/07/sentinel-3-ampli-user-handbook/S3_AMPLI_User_Handbook.pdf (last access: 15 May 2025), 2025b.
Aublanc, J., Moreau, T., Thibaut, P., Boy, F., Rémy, F., and Picot, N.: Evaluation of SAR altimetry over the Antarctic ice sheet from CryoSat-2 acquisitions, Adv. Space Res., 62, 1307–1323, https://doi.org/10.1016/j.asr.2018.06.043, 2018.
Aublanc, J., Thibaut, P., Guillot, A., Boy, F., and Picot, N.: Ice Sheet Topography from a New CryoSat-2 SARIn Processing Chain, and Assessment by Comparison to ICESat-2 over Antarctica, Remote Sens.-Basel, 13, 4508, https://doi.org/10.3390/rs13224508, 2021.
Berthier, E., Vincent, C., Magnússon, E., Gunnlaugsson, Á. Þ., Pitte, P., Le Meur, E., Masiokas, M., Ruiz, L., Pálsson, F., Belart, J. M. C., and Wagnon, P.: Glacier topography and elevation changes derived from Pléiades sub-meter stereo images, The Cryosphere, 8, 2275–2291, https://doi.org/10.5194/tc-8-2275-2014, 2014.
Brenner, A. C., Blndschadler, R. A., Thomas, R. H., and Zwally, H. J.: Slope-induced errors in radar altimetry over continental ice sheets, J. Geophys. Res., 88, 1617–1623, https://doi.org/10.1029/JC088iC03p01617, 1983.
Brenner, A. C., DiMarzio, J. P., and Zwally, H. J.: Precision and Accuracy of Satellite Radar and Laser Altimeter Data Over the Continental Ice Sheets, IEEE T. Geosci. Remote, 45, 321–331, https://doi.org/10.1109/TGRS.2006.887172, 2007.
Brown, G.: The average impulse response of a rough surface and its applications, IEEE T. Antenn. Propag., 25, 67–74, https://doi.org/10.1109/TAP.1977.1141536, 1977.
Brunt, K. M., Smith, B. E., Sutterley, T. C., Kurtz, N. T., and Neumann, T. A.: Comparisons of Satellite and Airborne Altimetry With Ground-Based Data From the Interior of the Antarctic Ice Sheet, Geophys. Res. Lett., 48, e2020GL090572, https://doi.org/10.1029/2020GL090572, 2021.
Canny, J.: A Computational Approach to Edge Detection, IEEE T. Pattern Anal., PAMI-8, 679–698, https://doi.org/10.1109/TPAMI.1986.4767851, 1986.
Cooper, A. P. R.: Slope Correction By Relocation For Satellite Radar Altimetry, In: 12th Canadian Symposium on Remote Sensing Geoscience and Remote Sensing Symposium, Vancouver, Canada, 2730–2733, https://doi.org/10.1109/IGARSS.1989.577978, 1989.
Donlon, C., Berruti, B., Buongiorno, A., Ferreira, M.-H., Féménias, P., Frerick, J., Goryl, P., Klein, U., Laur, H., Mavrocordatos, C., Nieke, J., Rebhan, H., Seitz, B., Stroede, J., and Sciarra, R.: The Global Monitoring for Environment and Security (GMES) Sentinel-3 mission, Remote Sens. Environ., 120, 37–57, https://doi.org/10.1016/j.rse.2011.07.024, 2012.
Flament, T. and Rémy, F.: Dynamic thinning of Antarctic glaciers from along-track repeat radar altimetry, J. Glaciol., 58, 830–840, https://doi.org/10.3189/2012JoG11J118, 2012.
Helm, V., Humbert, A., and Miller, H.: Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2, The Cryosphere, 8, 1539–1559, https://doi.org/10.5194/tc-8-1539-2014, 2014.
Helm, V., Dehghanpour, A., Hänsch, R., Loebel, E., Horwath, M., and Humbert, A.: AWI-ICENet1: a convolutional neural network retracker for ice altimetry, The Cryosphere, 18, 3933–3970, https://doi.org/10.5194/tc-18-3933-2024, 2024.
Howat, I. M., Porter, C., Smith, B. E., Noh, M.-J., and Morin, P.: The Reference Elevation Model of Antarctica, The Cryosphere, 13, 665–674, https://doi.org/10.5194/tc-13-665-2019, 2019.
Huang, Q., McMillan, M., Muir, A., Phillips, J., and Slater, T.: Multipeak retracking of radar altimetry waveforms over ice sheets, Remote Sens. Environ., 303, 114020, https://doi.org/10.1016/j.rse.2024.114020, 2024.
Intergovernmental Panel on Climate Change (IPCC) (Ed.): Ocean, Cryosphere and Sea Level Change, In: Climate Change 2021 – The Physical Science Basis: Working Group I Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, 1211–1362, https://doi.org/10.1017/9781009157896.011, 2023.
Lacroix, P., Dechambre, M., Legrésy, B., Blarel, F., and Rémy, F.: On the use of the dual-frequency ENVISAT altimeter to determine snowpack properties of the Antarctic ice sheet, Remote Sens. Environ., 112, 1712–1729, https://doi.org/10.1016/j.rse.2007.08.022, 2008.
Landy, J. C., Tsamados, M., and Scharien, R. K.: A Facet-Based Numerical Model for Simulating SAR Altimeter Echoes From Heterogeneous Sea Ice Surfaces, IEEE T. Geosci. Remote, 57, 4164–4180, https://doi.org/10.1109/TGRS.2018.2889763, 2019.
Larue, F., Picard, G., Aublanc, J., Arnaud, L., Robledano-Perez, A., LE Meur, E., Favier, V., Jourdain, B., Savarino, J., and Thibaut, P.: Radar altimeter waveform simulations in Antarctica with the Snow Microwave Radiative Transfer Model (SMRT), Remote Sens. Environ., 263, 112534, https://doi.org/10.1016/j.rse.2021.112534, 2021.
Legrésy, B. and Rémy, F.: Using the temporal variability of satellite radar altimetric observations to map surface properties of the Antarctic ice sheet, J. Glaciol., 44, 197–206, https://doi.org/10.3189/S0022143000002537, 1998.
Legresy, B., Papa, F., Remy, F., Vinay, G., Van Den Bosch, M., and Zanife, O.-Z.: ENVISAT radar altimeter measurements over continental surfaces and ice caps using the ICE-2 retracking algorithm, Remote Sens. Environ., 95, 150–163, https://doi.org/10.1016/j.rse.2004.11.018, 2005.
Li, W., Slobbe, C., and Lhermitte, S.: A leading-edge-based method for correction of slope-induced errors in ice-sheet heights derived from radar altimetry, The Cryosphere, 16, 2225–2243, https://doi.org/10.5194/tc-16-2225-2022, 2022.
Markus, T., Neumann, T., Martino, A., Abdalati, W., Brunt, K., Csatho, B., Farrell, S., Fricker, H., Gardner, A., Harding, D., Jasinski, M., Kwok, R., Magruder, L., Lubin, D., Luthcke, S., Morison, J., Nelson, R., Neuenschwander, A., Palm, S., Popescu, S., Shum, C., Schutz, B. E., Smith, B., Yang, Y., and Zwally, J.: The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2): Science requirements, concept, and implementation, Remote Sens. Environ., 190, 260–273, https://doi.org/10.1016/j.rse.2016.12.029, 2017.
McMillan, M., Muir, A., Shepherd, A., Escolà, R., Roca, M., Aublanc, J., Thibaut, P., Restano, M., Ambrozio, A., and Benveniste, J.: Sentinel-3 Delay-Doppler altimetry over Antarctica, The Cryosphere, 13, 709–722, https://doi.org/10.5194/tc-13-709-2019, 2019.
McMillan, M., Muir, A., and Donlon, C.: Brief communication: Ice sheet elevation measurements from the Sentinel-3A and Sentinel-3B tandem phase, The Cryosphere, 15, 3129–3134, https://doi.org/10.5194/tc-15-3129-2021, 2021.
Moholdt, G., Nuth, C., Hagen, J. O., and Kohler, J.: Recent elevation changes of Svalbard glaciers derived from ICESat laser altimetry, Remote Sens. Environ., 114, 2756–2767, https://doi.org/10.1016/j.rse.2010.06.008, 2010.
Morlighem, M., Rignot, E., Binder, T., Blankenship, D., Drews, R., Eagles, G., Eisen, O., Ferraccioli, F., Forsberg, R., Fretwell, P., Goel, V., Greenbaum, J. S., Gudmundsson, H., Guo, J., Helm, V., Hofstede, C., Howat, I., Humbert, A., Jokat, W., Karlsson, N. B., Lee, W. S., Matsuoka, K., Millan, R., Mouginot, J., Paden, J., Pattyn, F., Roberts, J., Rosier, S., Ruppel, A., Seroussi, H., Smith, E. C., Steinhage, D., Sun, B., van den Broeke, M. R., van Ommen, T. D., van Wessem, M., and Young, D. A.: Deep glacial troughs and stabilizing ridges unveiled beneath the margins of the Antarctic ice sheet, Nat. Geosci., 13, 132–137, https://doi.org/10.1038/s41561-019-0510-8, 2020.
Otosaka, I. N., Horwath, M., Mottram, R., and Nowicki, S.: Mass Balances of the Antarctic and Greenland Ice Sheets Monitored from Space, Surv. Geophys., 44, 1615–1652, https://doi.org/10.1007/s10712-023-09795-8, 2023.
Raney, R. K.: The delay/Doppler radar altimeter, IEEE T. Geosci. Remote, 36, 1578–1588, https://doi.org/10.1109/36.718861, 1998.
Rémy, F. and Parouty, S.: Antarctic Ice Sheet and Radar Altimetry: A Review, Remote Sens.-Basel, 1, 1212–1239, https://doi.org/10.3390/rs1041212, 2009.
Ridley, J. K. and Partington, K. C.: A model of satellite radar altimeter return from ice sheets, Int. J. Remote Sens., 9, 601–624, https://doi.org/10.1080/01431168808954881, 1988.
Roemer, S., Legrésy, B., Horwath, M., and Dietrich, R.: Refined analysis of radar altimetry data applied to the region of the subglacial Lake Vostok/Antarctica, Remote Sens. Environ., 106, 269–284, https://doi.org/10.1016/j.rse.2006.02.026, 2007.
Scott, R. F., Wingham, D. J., and Baker, S. G.: ENVISAT RA2/MWR Product Handbook, https://earth.esa.int/eogateway/documents/20142/37627/ENVISAT-RA-2-MWR-Product-Handbook.pdf (last access: 25 March 2025), 2007.
Sentinel-3 Instrument Processing Facility team: Sentinel-3 Level 2 SRAL MWR Algorithm Theoretical Baseline Definition, https://sentiwiki.copernicus.eu/__attachments/1672112/S3MPC.ATBD.LI - Sentinel-3 Level 2 SRAL MWR-LI ATBD 2023 - 4.2.pdf?inst-v=b88bce31-6a7b-41d2-99d5-181e8ab7e5d5 (last access: 25 March 2025), 2023.
Sentinel-3 MPC consortium: S3MPC STM Annual Performance Report – Year 2023, https://sentiwiki.copernicus.eu/__attachments/1681931/S3MPC-STM_RP_0139 - STM Annual Performance Report 2023 - 1.1.pdf?inst-v=b88bce31-6a7b-41d2-99d5-181e8ab7e5d5 (last access: 25 March 2025), 2024.
Simonsen, S. B. and Sørensen, L. S.: Implications of changing scattering properties on Greenland ice sheet volume change from Cryosat-2 altimetry, Remote Sens. Environ., 190, 207–216, https://doi.org/10.1016/j.rse.2016.12.012, 2017.
Smith, B., Sutterley, T., Dickinson, S., Jelley, B. P., Felikson, D., Neumann, T. A., Fricker, H. A., Gardner, A. S., Padman, L., Markus, T., Kurtz, N., Bhardwaj, S., Hancock, D., and Lee, J.: ATLAS/ICESat-2 L3B Gridded Antarctic and Arctic Land Ice Height Change. (ATL15, Version 3), Boulder, Colorado USA, NASA National Snow and Ice Data Center Distributed Active Archive Center [data set], https://doi.org/10.5067/ATLAS/ATL15.003, 2023.
Toutin, T.: Impact of terrain slope and aspect on radargrammetric DEM accuracy, ISPRS J. Photogramm., 57, 228–240, https://doi.org/10.1016/S0924-2716(02)00123-5, 2002.
Wang, F., Bamber, J. L., and Cheng, X.: Accuracy and Performance of CryoSat-2 SARIn Mode Data Over Antarctica, IEEE Geosci. Remote, 12, 1516–1520, https://doi.org/10.1109/LGRS.2015.2411434, 2015.
Wingham, D. J., Rapley, C. G., and Griffiths, H.: New techniques in satellite altimeter tracking systems, in: Proceedings of the IGARSS Symposium, vol. SP-254, edited by: Guyenne, T. D. and Hunt, J. J., European Space Agency, Zurich, September 1986, 1339–1344, https://www.researchgate.net/publication/269518510_New_Techniques_in_Satellite_Altimeter_Tracking_Systems (last access: 25 March 2025), 1986.
Zwally, H. Jay, Mario B. Giovinetto, Matthew A. Beckley, and Jack L. Saba, 2012, Antarctic and Greenland Drainage Systems, GSFC Cryospheric Sciences Laboratory, https://earth.gsfc.nasa.gov/cryo/data/polar-altimetry/antarctic-and-greenland-drainage-systems (last access: 25 March 2025), 2012.
Short summary
In this study we developed a novel processing chain to derive the ice sheet topography from Sentinel-3 altimetry measurements (named "AMPLI"). The major innovation lies in the use of numerical simulations to geolocate the radar impact point on the ground. The performance improvement is substantial compared to ground segment processing. Furthermore, with AMPLI we show that Sentinel-3 estimates the surface elevation change of the Antarctic ice sheet with a high level of agreement with ICESat-2.
In this study we developed a novel processing chain to derive the ice sheet topography from...