{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,2]],"date-time":"2026-01-02T17:08:35Z","timestamp":1767373715354,"version":"build-2065373602"},"reference-count":32,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2019,6,24]],"date-time":"2019-06-24T00:00:00Z","timestamp":1561334400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Key R&amp;D Program of China","award":["2016YFC1401000"],"award-info":[{"award-number":["2016YFC1401000"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["41876204"],"award-info":[{"award-number":["41876204"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>When the Haiyang-2B (HY-2B) was launched into space to form a star network with the Haiyang-2A (HY-2A), it provided new data sources for the sea ice research of the Earth\u2019s polar regions. The ability of altimeter echoes to distinguish sea ice and sea water is usable in operational ice charting. In this research study, the level 1B (L1B) data of HY-2A\/B altimeter from November 2018 was used to analyze the altimeter waveforms from the polar regions. The Suboptimal Maximum Likelihood Estimation (SMLE) and Offset Center of Gravity (OCOG) tracking packages could maintain the waveform characteristics of diffused and quasi-specular surfaces by comparison. Also, they could be utilized to distinguish sea ice from seawater in the polar regions. It was determined that the types of echoes obtained from the seawater were diffuse. Also, some \u201cocean-like\u201d waveform data had existed for the old ice formations in the Arctic regions during the study period. The types of echoes obtained from Arctic sea ice were found to be mainly quasi-specular. In the present study, three methods (Threshold segmentation, K-nearest-neighbor (KNN), and Lib-Support Vector machine (LIBSVM)) with four waveform parameters (Automatic Gain Control (AGC) and Pulse Peaking (PP) values of the Ku and C Bands) were adopted to distinguish between the sea ice and seawater areas. The accuracy rate of the separation results for the LIBSVM except band Ku from HY-2B ALT was found to be less than 40% in Antarctic. Meanwhile, the other two methods were observed to have maintained the waveforms correctly at accuracy rates of approximately 80% in Antarctic and the Arctic. In addition, the observed distinguishing errors were located in the regions of the old ice of the Arctic region. In addition, due to the summer melting processes, the large number of ice floes and the snow cover had made it difficult to distinguish the seawater and sea ice in the Antarctic regions.<\/jats:p>","DOI":"10.3390\/rs11121490","type":"journal-article","created":{"date-parts":[[2019,6,24]],"date-time":"2019-06-24T11:01:57Z","timestamp":1561374117000},"page":"1490","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["A Study of the Technology Used to Distinguish Sea Ice and Seawater on the Haiyang-2A\/B (HY-2A\/B) Altimeter Data"],"prefix":"10.3390","volume":"11","author":[{"given":"Chengfei","family":"Jiang","sequence":"first","affiliation":[{"name":"School of Marine Science and Technology, Tianjin University, Tianjin 300072, China"},{"name":"National Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China"},{"name":"Key Laboratory of Space Ocean Remote Sensing and Application, State Oceanic Administration, Beijing 100081, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mingsen","family":"Lin","sequence":"additional","affiliation":[{"name":"National Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China"},{"name":"Key Laboratory of Space Ocean Remote Sensing and Application, State Oceanic Administration, Beijing 100081, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hao","family":"Wei","sequence":"additional","affiliation":[{"name":"School of Marine Science and Technology, Tianjin University, Tianjin 300072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,6,24]]},"reference":[{"key":"ref_1","unstructured":"Untersteiner, N. (1984). The Global Climate, Cambridge University Press."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Shokr, M., and Sinha, N. (2015). Sea Ice: Physics and Remote Sensing, John Wiley & Sons.","DOI":"10.1002\/9781119028000"},{"key":"ref_3","unstructured":"Dwyer, R., and Godin, R. (1980). Determining Sea-Ice Boundaries and Ice Roughness Using GEOS-3 Altimeter Data."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"150","DOI":"10.1038\/307150a0","article-title":"First observations of the interaction of ocean swell with sea ice using satellite radar altimeter data","volume":"307","author":"Rapley","year":"1984","journal-title":"Nature"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1553","DOI":"10.1029\/GL017i010p01553","article-title":"Seasonal and inter-annual variations in Antarctic sea ice extent as mapped by radar altimetry","volume":"17","author":"Laxon","year":"1990","journal-title":"Geophys. Res. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"915","DOI":"10.1080\/01431169408954124","article-title":"Sea ice altimeter processing scheme at the EODC","volume":"15","author":"Laxon","year":"1994","journal-title":"Int. J. Remote Sens."},{"key":"ref_7","first-page":"112","article-title":"Sea ice extent mapping using the ERS-1 radar altimeter","volume":"3","author":"Laxon","year":"1994","journal-title":"Adv. Remote Sens."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"121","DOI":"10.5194\/tc-10-121-2016","article-title":"Utilisation of CryoSat-2 SAR altimeter in operational ice charting","volume":"10","author":"Rinne","year":"2016","journal-title":"Cryosphere"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1948","DOI":"10.1109\/LGRS.2017.2743339","article-title":"Sea ice classification using Cryosat-2 altimeter data by optimal classifier\u2013feature assembly","volume":"14","author":"Shen","year":"2017","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"18015","DOI":"10.1029\/JC095iC10p18015","article-title":"Estimation of sea ice type and concentration by linear unmixing of Geosat altimeter waveforms","volume":"95","author":"Chase","year":"1990","journal-title":"J. Geophys. Res. Ocean."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"4555","DOI":"10.1029\/90JC01954","article-title":"Ku band airborne radar altimeter observations of marginal sea ice during the 1984 Marginal Ice Zone Experiment","volume":"96","author":"Drinkwater","year":"1991","journal-title":"J. Geophys. Res. Ocean."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Giles, K.A., Laxon, S.W., and Ridout, A.L. (2008). Circumpolar thinning of Arctic sea ice following the 2007 record ice extent minimum. Geophys. Res. Lett., 35.","DOI":"10.1029\/2008GL035710"},{"key":"ref_13","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_14","unstructured":"Ridout, A., Ivanova, N., Tonboe, R., Laxon, S., Timms, G., Kern, S., and Kloster, K. (2012). Algorithm Theoretical Basis Document."},{"key":"ref_15","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_16","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1007\/s11707-014-0461-8","article-title":"Assimilation of HY-2A scatterometer sea surface wind data in a 3DVAR data assimilation system\u2014A case study of Typhoon Bolaven","volume":"9","author":"Yu","year":"2015","journal-title":"Front. Earth Sci."},{"key":"ref_17","unstructured":"Lin, M., and Jiang, X. (2014, January 13\u201318). HY-2 ocean dynamic environment mission and payloads. Proceedings of the 2014 IEEE Geoscience and Remote Sensing Symposium, Quebec City, QC, Canada."},{"key":"ref_18","unstructured":"Pan, D., Gong, F., and Chen, J. (2019, June 20). The Chinese environment satellite mission status and future plan. Available online: https:\/\/www.spiedigitallibrary.org\/conference-proceedings-of-spie\/7474\/747424\/The-Chinese-environment-satellite-mission-status-and-future-plan\/10.1117\/12.830251.full."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Xu, K., Jiang, J., and Liu, H. (2007, January 23\u201328). A new tracker for ocean-land compatible radar altimeter. Proceedings of the 2007 IEEE International Geoscience and Remote Sensing Symposium, Barcelona, Spain.","DOI":"10.1109\/IGARSS.2007.4423677"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2965","DOI":"10.1029\/JC095iC03p02965","article-title":"Ionospheric effects on Geosat altimeter observations","volume":"95","author":"Musman","year":"1990","journal-title":"J. Geophys. Res. Ocean."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"7791","DOI":"10.1002\/2015JC011135","article-title":"Seasonal and interannual variability of fast ice extent in the southeastern Laptev Sea between 1999 and 2013","volume":"120","author":"Selyuzhenok","year":"2015","journal-title":"J. Geophys. Res. Ocean."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1029\/94GL00178","article-title":"A comparison of the performance of the ice and ocean tracking modes of the ERS-1 radar altimeter over non-ocean surfaces","volume":"21","author":"Scott","year":"1994","journal-title":"Geophys. Res. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Peacock, N.R., and Laxon, S.W. (2004). Sea surface height determination in the Arctic Ocean from ERS altimetry. J. Geophys. Res. Ocean., 109.","DOI":"10.1029\/2001JC001026"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1315","DOI":"10.5194\/tc-7-1315-2013","article-title":"Waveform classification of airborne synthetic aperture radar altimeter over Arctic sea ice","volume":"7","author":"Zygmuntowska","year":"2013","journal-title":"Cryosphere"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1607","DOI":"10.5194\/tc-8-1607-2014","article-title":"Sensitivity of CryoSat-2 Arctic sea-ice freeboard and thickness on radar-waveform interpretation","volume":"8","author":"Ricker","year":"2014","journal-title":"Cryosphere"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"522","DOI":"10.1080\/01490419.2015.1019655","article-title":"Sea Ice Leads Detection Using SARAL\/AltiKa Altimeter","volume":"38","author":"Zakharova","year":"2015","journal-title":"Mar. Geod."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1955","DOI":"10.5194\/tc-9-1955-2015","article-title":"Lead detection in Arctic sea ice from CryoSat-2: Quality assessment, lead area fraction and width distribution","volume":"9","author":"Wernecke","year":"2015","journal-title":"Cryosphere"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1795","DOI":"10.1029\/92GL01698","article-title":"Altimetric gravity anomalies in the Norwegian-Greenland Sea-Preliminary results from the ERS-1 35 days repeat mission","volume":"19","author":"Knudsen","year":"1992","journal-title":"Geophys. Res. Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"4709","DOI":"10.1029\/90JC02261","article-title":"The aerodynamic roughness of different types of sea ice","volume":"96","author":"Guest","year":"1991","journal-title":"J. Geophys. Res. Ocean."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"851","DOI":"10.1080\/01431169508954448","article-title":"Laboratory measurements of radar backscatter from bare and snow-covered saline ice sheets","volume":"16","author":"Beaven","year":"1995","journal-title":"Remote Sens."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1109\/JOE.1977.1145328","article-title":"The average impulse responce of a rough surface and its applications","volume":"2","author":"Brown","year":"1977","journal-title":"IEEE J. Ocean. Eng."},{"key":"ref_32","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":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/12\/1490\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:00:48Z","timestamp":1760187648000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/12\/1490"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,6,24]]},"references-count":32,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2019,6]]}},"alternative-id":["rs11121490"],"URL":"https:\/\/doi.org\/10.3390\/rs11121490","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2019,6,24]]}}}