{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,7]],"date-time":"2026-04-07T06:22:11Z","timestamp":1775542931433,"version":"3.50.1"},"reference-count":60,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2016,6,24]],"date-time":"2016-06-24T00:00:00Z","timestamp":1466726400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Accurate circum-Antarctic sea-ice thickness is urgently required to better understand the different sea-ice cover evolution in both polar regions. Satellite radar and laser altimetry are currently the most promising tools for sea-ice thickness retrieval. We present qualitative inter-comparisons of winter and spring circum-Antarctic sea-ice thickness computed with different approaches from Ice Cloud and land Elevation Satellite (ICESat) laser altimeter total (sea ice plus snow) freeboard estimates. We find that approach A, which assumes total freeboard equals snow depth, and approach B, which uses empirical linear relationships between freeboard and thickness, provide the lowest sea-ice thickness and the smallest winter-to-spring increase in seasonal average modal and mean sea-ice thickness: A: 0.0 m and 0.04 m, B: 0.17 and 0.16 m, respectively. Approach C uses contemporary snow depth from satellite microwave radiometry, and we derive comparably large sea-ice thickness. Here we observe an unrealistically large winter-to-spring increase in seasonal average modal and mean sea-ice thickness of 0.68 m and 0.65 m, respectively, which we attribute to biases in the snow depth. We present a conceptually new approach D. It assumes that the two-layer system (sea ice, snow) can be represented by one layer. This layer has a modified density, which takes into account the influence of the snow on sea-ice buoyancy. With approach D we obtain thickness values and a winter-to-spring increase in average modal and mean sea-ice thickness of 0.17 m and 0.23 m, respectively, which lay between those of approaches B and C. We discuss retrieval uncertainty, systematic uncertainty sources, and the impact of grid resolution. We find that sea-ice thickness obtained with approaches C and D agrees best with independent sea-ice thickness information\u2014if we take into account the potential bias of in situ and ship-based observations.<\/jats:p>","DOI":"10.3390\/rs8070538","type":"journal-article","created":{"date-parts":[[2016,6,25]],"date-time":"2016-06-25T21:21:45Z","timestamp":1466889705000},"page":"538","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":45,"title":["Antarctic Sea-Ice Thickness Retrieval from ICESat: Inter-Comparison of Different Approaches"],"prefix":"10.3390","volume":"8","author":[{"given":"Stefan","family":"Kern","sequence":"first","affiliation":[{"name":"Integrated Climate Data Center (ICDC), Center for Earth System Research and Sustainability (CEN), University of Hamburg, 20144 Hamburg, Germany"}]},{"given":"Burcu","family":"Ozsoy-\u00c7i\u00e7ek","sequence":"additional","affiliation":[{"name":"Polar Research Center (PolReC), Maritime Faculty, Istanbul Technical University (ITU), 34940 Istanbul, Turkey"}]},{"given":"Anthony","family":"Worby","sequence":"additional","affiliation":[{"name":"Antarctic Climate and Ecosystems Climate Research Center (ACE CRC), University of Tasmania, 7000 Hobart, TAS, Australia"}]}],"member":"1968","published-online":{"date-parts":[[2016,6,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"9377","DOI":"10.1175\/JCLI-D-14-00605.1","article-title":"Global sea ice coverage from satellite data: Annual cycle and 35-yr trends","volume":"27","author":"Parkinson","year":"2014","journal-title":"J. Clim."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"871","DOI":"10.5194\/tc-6-871-2012","article-title":"Antarctic sea ice variability and trends, 1979\u20132010","volume":"6","author":"Parkinson","year":"2012","journal-title":"Cryosphere"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1016\/j.ocemod.2013.01.003","article-title":"A model reconstruction of the Antarctic sea-ice thickness and volume changes over 1980\u20132008 using data assimilation","volume":"64","author":"Massonnet","year":"2013","journal-title":"Ocean Model."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3807","DOI":"10.1002\/jgrc.20252","article-title":"Sea-ice thickness retrieval algorithms based on in-situ surface elevation and thickness values for application to altimetry","volume":"118","author":"Ackley","year":"2013","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_5","unstructured":"Worby, A.P., and Allison, I. (1999). A Ship-Based Technique for Observing Antarctic Sea Ice: Part I Observational Techniques and Results, Antarctic Cooperative Research Centre. Research Report No. 14."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Worby, A.P., Geiger, C.A., Paget, M.J., Van Woert, M.L., Ackley, S.F., and DeLiberty, T.L. (2008). The thickness distribution of Antarctic sea ice. J. Geophys. Res., 113.","DOI":"10.1029\/2007JC004254"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1985","DOI":"10.1109\/TGRS.2014.2351497","article-title":"Comparison of SSM\/I and AMSR-E sea ice concentrations with ASPeCt ship observations around Antarctica","volume":"53","author":"Beitsch","year":"2015","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"9057","DOI":"10.1029\/1999JC000027","article-title":"Sea ice transports in the Weddell Sea","volume":"106","author":"Harms","year":"2001","journal-title":"J. Geophys. Res."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"209","DOI":"10.5194\/essd-5-209-2013","article-title":"Sea ice draft in the Weddell Sea measured by upward looking sonars","volume":"5","author":"Behrendt","year":"2013","journal-title":"Earth Syst. Sci. Data"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1038\/ngeo2299","article-title":"Thick and deformed Antarctic sea ice mapped with autonomous underwater vehicles","volume":"8","author":"Williams","year":"2015","journal-title":"Nat. Geosci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1250","DOI":"10.1016\/j.dsr2.2010.12.005","article-title":"Estimating the annual cycle of sea-ice thickness and volume in the Ross Sea","volume":"58","author":"DeLiberty","year":"2011","journal-title":"Deep Sea Res."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"383","DOI":"10.3189\/2015AoG69A763","article-title":"Antarctic sea-ice thickness and volume estimates from ice charts between 1995 and 1998","volume":"56","author":"Bernstein","year":"2015","journal-title":"Ann. Glaciol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"269","DOI":"10.3189\/172756406781811745","article-title":"Estimation of thin sea-ice thickness from NOAA AVHRR data in a polynya off the Wilkes Land coast, East Antarctica","volume":"44","author":"Tamura","year":"2006","journal-title":"Ann. Glaciol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1757","DOI":"10.1175\/JTECH2113.1","article-title":"Estimation of thin ice thickness and detection of fast ice from SSM\/I data in the Antarctic Ocean","volume":"24","author":"Tamura","year":"2007","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1016\/j.jmarsys.2006.11.008","article-title":"The areas and ice production of the western and central Ross Sea polynyas, 1992\u20132002, and their relation to the B-15 and C-19 iceberg events of 2000 and 2002","volume":"68","author":"Martin","year":"2007","journal-title":"J. Mar. Syst."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"3650","DOI":"10.1175\/JCLI-D-14-00369.1","article-title":"Circumpolar mapping of Antarctic coastal polynyas and landfast sea ice: Relationship and variability","volume":"28","author":"Nihashi","year":"2015","journal-title":"J. Clim."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1109\/LGRS.2008.2011061","article-title":"Observation of sea-ice thickness using ENVISAT data from L\u00fctzow-Holm Bay, East Antarctica","volume":"6","author":"Nakamura","year":"2009","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"4122","DOI":"10.1109\/TGRS.2013.2279799","article-title":"Estimation of sea-ice thickness in Ross and Weddell Seas from SSM\/I brightness temperatures","volume":"52","author":"Aulicino","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"997","DOI":"10.5194\/tc-8-997-2014","article-title":"SMOS-derived thin sea-ice thickness: Algorithm baseline, product specification and initial verification","volume":"8","author":"Kaleschke","year":"2014","journal-title":"Cryosphere"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Wadhams, P., Parmiggiani, F.F., de Cariolis, G., Desiderio, D., and Doble, M.J. (2004). SAR imaging of wave dispersion in Antarctic pancake ice and its use in measuring ice thickness. Geophys. Res. Lett., 31.","DOI":"10.1029\/2004GL020340"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"4473","DOI":"10.1002\/2015GL063628","article-title":"Relating wave attenuation to pancake ice thickness using field measurements and model results","volume":"42","author":"Doble","year":"2015","journal-title":"Geophys. Res. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"947","DOI":"10.1038\/nature02050","article-title":"High interannual variability of sea-ice thickness in the Arctic region","volume":"425","author":"Laxon","year":"2003","journal-title":"Nature"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"732","DOI":"10.1002\/grl.50193","article-title":"CryoSat-2 estimates of Arctic sea-ice thickness and volume","volume":"40","author":"Laxon","year":"2013","journal-title":"Geophys. Res. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Giles, K.A., Laxon, S.W., and Worby, A.P. (2008). Antarctic sea ice elevation from satellite radar altimetry. Geophys. Res. Lett., 35.","DOI":"10.1029\/2007GL031572"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"365","DOI":"10.1109\/TGRS.2009.2028237","article-title":"Field investigations of Ku-Band radar penetration into snow cover on Antarctic sea ice","volume":"48","author":"Willatt","year":"2010","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_26","first-page":"4893","article-title":"About the consistency between Envisat and CryoSat-2 radar freeboard retrieval over Antarctic sea ice","volume":"9","author":"Schwegmann","year":"2015","journal-title":"Cryosphere"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"242","DOI":"10.3189\/172756411795931570","article-title":"Freeboard, snow depth and sea-ice roughness in East Antarctica from in situ and multiple satellite data","volume":"52","author":"Markus","year":"2011","journal-title":"Ann. Glaciol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2438","DOI":"10.1002\/jgrc.20179","article-title":"Sea-ice thickness estimations from ICESat altimetry over the Bellingshausen and Amundsen Seas, 2003\u20132009","volume":"118","author":"Xie","year":"2013","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Zwally, H.J., Yi, D., Kwok, R., and Zhao, Y. (2008). ICESat measurements of sea ice freeboard and estimates of sea-ice thickness in the Weddell Sea. J. Geophys. Res., 113.","DOI":"10.1029\/2007JC004284"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"43","DOI":"10.3189\/172756411795931480","article-title":"ICESat observations of seasonal and interannual variations of sea-ice freeboard and estimated thickness in the Weddell Sea, Antarctica (2003\u20132009)","volume":"52","author":"Yi","year":"2011","journal-title":"Ann. Glaciol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"107","DOI":"10.3189\/2015AoG69A736","article-title":"Uncertainties in Antarctic sea-ice thickness retrieval from ICESat","volume":"56","author":"Kern","year":"2015","journal-title":"Ann. Glaciol."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Kurtz, N.T., and Markus, T. (2012). Satellite observations of Antarctic sea-ice thickness and volume. J. Geophys. Res., 117.","DOI":"10.1029\/2012JC008141"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"4141","DOI":"10.1002\/2014JC009943","article-title":"Snow depth of the Weddell and Bellingshausen sea ice covers from IceBridge surveys in 2010 and 2011: An examination","volume":"119","author":"Kwok","year":"2014","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Kern, S., and Ozsoy-Cicek, B. (2016). Satellite remote sensing of snow depth on Antarctic sea ice: An inter-comparison of two empirical approaches. Remote Sens., 8.","DOI":"10.3390\/rs8060450"},{"key":"ref_35","unstructured":"Zwally, H.J., Schutz, R., Bentley, C., Bufton, J., Herring, T., Minster, J., Spinhirne, J., and Ross, T. (2011). GLAS\/ICESat L2 Sea Ice Altimetry Data, National Snow and Ice Data Center. Version 33."},{"key":"ref_36","unstructured":"Cavalieri, D.J., Markus, T., and Comiso, J.C. (2003). AMSR-E\/Aqua Daily L3 12.5 km Brightness Temperature, Sea Ice Concentration, and Snow Depth Polar Grids, National Snow and Ice Data Centre."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"526","DOI":"10.1080\/07038992.2001.10854892","article-title":"SSM\/I sea ice remote sensing for mesoscale ocean-atmosphere interaction analysis","volume":"27","author":"Kaleschke","year":"2001","journal-title":"Can. J. Remote Sens."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"411","DOI":"10.1111\/j.1600-0870.2010.00457.x","article-title":"Climatology of the Nordic (Irminger, Greenland, Barents, Kara and White\/Pechora) Seas ice cover based on 85 GHz satellite microwave radiometry: 1992\u20132008","volume":"62","author":"Kern","year":"2010","journal-title":"Tellus"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/0165-232X(88)90035-3","article-title":"Formation of slush on floating ice","volume":"15","author":"Knight","year":"1988","journal-title":"Cold Reg. Sci. Technol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"321","DOI":"10.3189\/172756406781811385","article-title":"Satellite-based estimates of sea-ice volume flux through Fram Strait","volume":"44","author":"Spreen","year":"2006","journal-title":"Ann. Glaciol."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Maksym, T., and Markus, T. (2008). Antarctic sea-ice thickness and snow-to-ice conversion from atmospheric reanalysis and passive microwave snow depth. J. Geophys. Res., 113.","DOI":"10.1029\/2006JC004085"},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Worby, A.P., Markus, T., Steer, A.D., Lytle, V.I., and Massom, R.A. (2008). Evaluation of AMSR-E snow depth product over East Antarctic sea ice using in situ measurements and aerial photography. J. Geophys. Res., 113.","DOI":"10.1029\/2007JC004181"},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Jeffries, M.O. (1998). Antarctic Sea Ice: Physical Processes, Interactions and Variability, AGU.","DOI":"10.1029\/AR074"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"2023","DOI":"10.1016\/j.dsr2.2004.07.024","article-title":"Winter sea-ice properties in Marguerite Bay, Antarctica","volume":"51","author":"Perovich","year":"2004","journal-title":"Deep Sea Res. II"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"288","DOI":"10.3189\/172756406781811268","article-title":"ARISE (Antarctic Remote Ice Sensing Experiment) in the East 2003: Validation of satellite-derived sea-ice data products","volume":"44","author":"Massom","year":"2006","journal-title":"Ann. Glaciol."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1029\/2006EO180001","article-title":"Sea ice feedbacks observed in Western Weddell Sea","volume":"87","author":"Hellmer","year":"2006","journal-title":"EOS"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1019","DOI":"10.1016\/j.dsr2.2010.10.027","article-title":"Sea ice and snow cover characteristics during the winter-spring transition in the Bellingshausen Sea: An overview of SIMBA 2007","volume":"58","author":"Lewis","year":"2011","journal-title":"Deep Sea Res. II"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1125","DOI":"10.1016\/j.dsr2.2010.12.001","article-title":"Regional-scale sea-ice and snow thickness distributions from in situ and satellite measurements over East Antarctica during SIPEX 2007","volume":"58","author":"Worby","year":"2011","journal-title":"Deep Sea Res. II"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"225","DOI":"10.3189\/172756411795931679","article-title":"Antarctic sea-ice altimetry: Scale and resolution effects on derived ice thickness distribution","volume":"52","author":"Weissling","year":"2011","journal-title":"Ann. Glaciol."},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Kwok, R., and Cunningham, G.F. (2015). Variability of Arctic sea-ice thickness and volume from CryoSat-2. Philos. Trans. R. Soc. A, 373.","DOI":"10.1098\/rsta.2014.0157"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"2188","DOI":"10.1109\/TGRS.2012.2211603","article-title":"Validating ICESat over thick sea ice in the Northern Canada Basin","volume":"51","author":"Connor","year":"2013","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"167","DOI":"10.3189\/2015AoG69A686","article-title":"Sea-ice freeboard retrieval using digital photon-counting laser altimetry","volume":"56","author":"Farrell","year":"2015","journal-title":"Ann. Glaciol."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"353","DOI":"10.3189\/2015AoG69A644","article-title":"Impact of spatial aliasing on sea-ice thickness measurements","volume":"56","author":"Geiger","year":"2015","journal-title":"Ann. Glaciol."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"2892","DOI":"10.1002\/jgrc.20228","article-title":"Arctic-scale assessment of satellite passive microwave-derived snow depth on sea ice using Operation Ice Bridge airborne data","volume":"118","author":"Brucker","year":"2013","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_55","doi-asserted-by":"crossref","unstructured":"Willmes, S., Haas, C., Nicolaus, M., and Bareiss, J. (2009). Satellite microwave observations of the interannual variability of snowmelt on sea ice in the Southern Ocean. J. Geophys. Res., 114.","DOI":"10.1029\/2008JC004919"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"35","DOI":"10.3402\/polar.v22i1.6441","article-title":"Improving sea ice type discrimination by the simultaneous use of SSM\/I and scatterometer data","volume":"22","author":"Voss","year":"2003","journal-title":"Polar Res."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"77","DOI":"10.3189\/2015AoG69A814","article-title":"Comparing methods of measuring sea-ice density in the East Antarctic","volume":"56","author":"Hutchings","year":"2015","journal-title":"Ann. Glaciol."},{"key":"ref_58","unstructured":"Haas, C., and Jochmann, P. (2003, January 16\u201319). Continuous EM and ULS thickness profiling in support of ice force measurements. Proceedings of the 17th International Conference on Port and Ocean Engineering under Arctic Conditions, POAC\u201903, Trondheim, Norway."},{"key":"ref_59","unstructured":"Frost, T., Heygster, G., and Kern, S. (2014). ANT D1.1 Passive Microwave Snow Depth on Antarctic Sea Ice Assessment, European Space Agency. ESA-CCI Sea Ice ECV Project Report, SICCI-ANT-PMW-SDASS-11-14."},{"key":"ref_60","unstructured":"Kern, S., Frost, T., and Heygster, G. (2014). ANT D1.3 Product User Guide (PUG) for Antarctic Snow Depth Product SD v1.1, European Space Agency. ESA-CCI Sea Ice ECV Project Report, SICCI-ANT-SD-PUG-14-08."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/8\/7\/538\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:24:42Z","timestamp":1760210682000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/8\/7\/538"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,6,24]]},"references-count":60,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2016,7]]}},"alternative-id":["rs8070538"],"URL":"https:\/\/doi.org\/10.3390\/rs8070538","relation":{"has-part":[{"id-type":"doi","id":"10.5194\/tc-16-4473-2022","asserted-by":"object"}]},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,6,24]]}}}