FN Archimer Export Format PT J TI On the Use of Doppler Shift for Sea Surface Wind Retrieval From SAR BT AF MOUCHE, Alexis COLLARD, Fabrice CHAPRON, Bertrand DAGESTAD, Knut-Frode GUITTON, Gilles JOHANNESSEN, Johnny A. KERBAOL, Vincent HANSEN, Morten Wergeland AS 1:1;2:1;3:2;4:3;5:2;6:3;7:1;8:3; FF 1:;2:;3:PDG-ODE-LOS;4:;5:PDG-ODE-LOS;6:;7:;8:; C1 CLS, Direct Radar Applicat, F-29280 Plouzane, France. IFREMER, CERSAT, F-29280 Plouzane, France. Nansen Environm & Remote Sensing Ctr, N-5006 Bergen, Norway. C2 CLS, FRANCE IFREMER, FRANCE NERSC, NORWAY SI BREST SE PDG-ODE-LOS IN WOS Ifremer jusqu'en 2018 copubli-france copubli-europe IF 3.47 TC 140 UR https://archimer.ifremer.fr/doc/00088/19896/17554.pdf LA English DT Article DE ;Doppler;surface wind;synthetic aperture radar (SAR) AB The synthetic aperture radar (SAR) Doppler centroid has been used to estimate the scatter line-of-sight radar velocity. In weak to moderate ocean surface current environment, the SAR Doppler centroid is dominated by the directionality and strength of wave-induced ocean surface displacements. In this paper, we show how this sea state signature can be used to improve surface wind retrieval from SAR. Doppler shifts of C-band radar return signals from the ocean are thoroughly investigated by colocating wind measurements from the ASCAT scatterometer with Doppler centroid anomalies retrieved from Envisat ASAR. An empirical geophysical model function (CDOP) is derived, predicting Doppler shifts at both VV and HH polarization as function of wind speed, radar incidence angle, and wind direction with respect to radar look direction. This function is used into a Bayesian inversion scheme in combination with wind from a priori forecast model and the normalized radar cross section (NRCS). The benefit of Doppler for SAR wind retrieval is shown in complex meteorological situations such as atmospheric fronts or low pressure systems. Using in situ information, validation reveals that this method helps to improve the wind direction retrieval. Uncertainty of the calibration of Doppler shift from Envisat ASAR hampers the inversion scheme in cases where NRCS and model wind are accurate and in close agreement. The method is however very promising with respect of future SAR missions, in particular Sentinel-1, where the Doppler centroid anomaly will be more robustly retrieved. PY 2012 PD JUN SO Ieee Transactions On Geoscience And Remote Sensing SN 0196-2892 PU Ieee-inst Electrical Electronics Engineers Inc VL 50 IS 7 UT 000305746900019 BP 2901 EP 2909 DI 10.1109/TGRS.2011.2174998 ID 19896 ER EF