FN Archimer Export Format PT J TI Copolarized and Cross‐Polarized SAR Measurements for High‐Resolution Description of Major Hurricane Wind Structures: Application to Irma Category 5 Hurricane BT AF Mouche, Alexis Chapron, Bertrand Knaff, John Zhao, Yili Zhang, Biao Combot, Clement AS 1:1;2:1;3:2;4:3;5:4;6:1; FF 1:PDG-ODE-LOPS-SIAM;2:PDG-ODE-LOPS-SIAM;3:;4:;5:;6:PDG-ODE-LOPS-SIAM; C1 IFREMER, Univ. Brest, CNRS, IRD, Laboratoire d'Océanographie Physique et Spatiale (LOPS) Brest, France NOAA/NESDIS Regional and Mesoscale Meteorological Branch Fort Collins Colorado ,USA National Ocean Technology CenterState Ocean Administration Tianjin 300112 ,China School of Marine SciencesNanjing University of Information Science and Technology Nanjing 210044, China C2 IFREMER, FRANCE NOAA, USA NOTC, CHINA UNIV NANJING, CHINA SI BREST SE PDG-ODE-LOPS-SIAM UM LOPS IN WOS Ifremer UMR copubli-int-hors-europe copubli-sud IF 3.559 TC 65 UR https://archimer.ifremer.fr/doc/00497/60898/64236.pdf LA English DT Article DE ;SAR;copolarization and cross-polarization;high resolution;category 5 Hurricane;Hurricane Irma AB C‐Band high resolution radar (SAR) is the only space‐borne instrument able to probe at very high resolution and over all ocean basins the sea surface under extreme weather conditions. When co‐analyzed with Stepped Frequency Microwave Radiometer (SFMR) wind estimates, the radar backscatter signals acquired in major Hurricanes from Sentinel‐1 and Radarsat‐2 SAR, reveal high sensitivity in the cross‐polarized channel for wind speeds up to 75 m/s. The combination of the two co‐ and cross‐ polarized channels can then be used to derive high resolution surface wind estimates. The retrieval methods and impacts of intense rainfall are discussed in the context of a Hurricane Irma (2017) case study. On September 7, 2017, Sentinel‐1 measurements intercepted Hurricane Irma when it was at category 5 intensity. When compared to SFMR, SAR‐derived wind speeds yield bias and rms, of about 1.5 m/s and 5.0 m/s, respectively. The retrieved wind structure parameters for the outer core are found to be in agreement with the Best‐Track and combined satellite and aircraft based analyses. SAR measurements uniquely describe the inner core and provide independent measurements of the maximum wind speed, the radius of maximum wind (RMW). Near the RMW a 65 m/s increase in wind speed in less than 10 km is detected, corresponding to an instantaneous absolute vorticity of order 210 times the Coriolis parameter. Using a parametric Holland model and the environmental surface pressure (1011 hPa), SAR‐derived wind speeds correspond to a central surface pressure of 918 hPa (921 hPa from the Best‐Track) in Irma's eye. PY 2019 PD JUL SO Journal Of Geophysical Research-oceans SN 2169-9275 PU American Geophysical Union (AGU) VL 124 IS 6 UT 000477722200024 BP 3905 EP 3922 DI 10.1029/2019JC015056 ID 60898 ER EF