{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,4]],"date-time":"2025-11-04T10:36:02Z","timestamp":1762252562825,"version":"build-2065373602"},"reference-count":41,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2017,5,12]],"date-time":"2017-05-12T00:00:00Z","timestamp":1494547200000},"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>This paper reports Ku-band normalized radar cross section (NRCS) at low incidence angles ranging from 0\u00b0 to 18\u00b0 and in the wind speed range from 6 to 70 m\/s. The precipitation radar onboard the tropical rainfall measuring mission and Jason-1 and 2 have provided 152 hurricanes observations between 2008 and 2013 that were collocated with stepped-frequency microwave radiometer measurements. It is found that the NRCS decreases with increasing incidence angle. The decrease is more dramatic in the 40\u201370 m\/s range of wind speeds than in the 6\u201320 m\/s range, indicating that the NRCS is very sensitive to low incidence angles under extreme wind conditions and insensitive to the extreme wind speed. Consequently, the sea surface appears relatively \u201csmooth\u201d to Ku-band electromagnetic microwaves. This phenomenon validates the observed drag coefficient reduction under extreme wind conditions, from a remote sensing viewpoint. Using the NRCS dependence on incidence angle under extreme wind conditions, we also present an empirical linear relationship between NRCS and incidence angles, which may assist future-satellites missions operating at small incidence angles to measure sea surface wind and wave field.<\/jats:p>","DOI":"10.3390\/rs9050474","type":"journal-article","created":{"date-parts":[[2017,5,12]],"date-time":"2017-05-12T11:03:53Z","timestamp":1494587033000},"page":"474","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Ku-Band Sea Surface Radar Backscatter at Low Incidence Angles under Extreme Wind Conditions"],"prefix":"10.3390","volume":"9","author":[{"given":"Xiuzhong","family":"Li","sequence":"first","affiliation":[{"name":"School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China"},{"name":"Jiangsu Research Center for Ocean Survey and Technology, Nanjing 210044, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6569-1998","authenticated-orcid":false,"given":"Biao","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China"},{"name":"Jiangsu Research Center for Ocean Survey and Technology, Nanjing 210044, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1250-4436","authenticated-orcid":false,"given":"Alexis","family":"Mouche","sequence":"additional","affiliation":[{"name":"School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China"},{"name":"Laboratoire d\u2019Oceanographie Spatiale, Centre de Brest, IFREMER, Plouzan\u00e9 29280, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1531-5262","authenticated-orcid":false,"given":"Yijun","family":"He","sequence":"additional","affiliation":[{"name":"School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China"},{"name":"Jiangsu Research Center for Ocean Survey and Technology, Nanjing 210044, China"}]},{"given":"William","family":"Perrie","sequence":"additional","affiliation":[{"name":"School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China"},{"name":"Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, NS B2Y4A2, Canada"}]}],"member":"1968","published-online":{"date-parts":[[2017,5,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1925","DOI":"10.1109\/LGRS.2016.2618604","article-title":"A Modified CFAR Algorithm Based on Object Proposals for Ship Target Detection in SAR Images","volume":"13","author":"Dai","year":"2016","journal-title":"IEEE Geosci. 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