The potential of QuikSCAT and WindSat observations for the estimation of sea surface wind vector under severe weather conditions - art. no. C09023

Type Publication
Date 2007-09
Language English
Copyright 2007 American Geophysical Union
Author(s) Quilfen Yves1, Prigent C2, Chapron Bertrand1, Mouche Alexis1, Houti N2
Affiliation(s) 1 : IFREMER, Lab Oceanog Spatiale, F-29280 Plouzane, France.
2 : Observ Paris, Lab Etud Rayonnement & Mat Astrophys, F-75014 Paris, France.
Source Journal of Geophysical Research ( JGR ) - Oceans (0148-0227) (American Geophysical Union), 2007-09 , Vol. 112 , N. C9 , P. NIL_49-NIL_66
DOI 10.1029/2007JC004163
WOS© Times Cited 32
Keyword(s) winds, scatterometer, Radiometer
Abstract The physics of remote sensing sea surface measurements is still poorly understood under severe weather conditions. Wind vector algorithms are usually developed for non-precipitating atmospheres and for wind speeds less than 20 m/s. In this study, we analyze observations from the QuikSCAT Ku-band scatterometer collocated with the WindSat full polarimetric microwave radiometer to estimate the potential of these two instruments for sea surface wind retrieval under severe weather conditions. The Jason altimeter provides independent measurements of wind speed and rain rate for comparison purposes. The sensitivity of the radar cross-sections and brightness temperatures to the wind speed and direction is directly studied from the observations and compared with semi empirical models. This study clearly demonstrates that wind vector retrieval under extreme condition is feasible. Comparisons between QuikSCAT and WindSat coincident observations evidence a better sensitivity of the active mode to low and moderate winds and more sensitivity to high wind speeds in the passive mode. Although the WindSat observations are affected by water vapor, cloud, and rain, especially at and above 18 GHz, the measurements are sensitive to wind speed even at high wind speeds. Contrarily to the active instrument, there is no saturation at high winds. The sensitivity clearly tends to increase for winds above 15 m/s. For the wind direction, the amplitude of the azimuthal modulation in the active mode decreases with increasing wind speed, while it increases for the passive measurements. The development of specific wind retrievals under severe weather conditions is encouraged and a simple illustration is provided.
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Quilfen Yves, Prigent C, Chapron Bertrand, Mouche Alexis, Houti N (2007). The potential of QuikSCAT and WindSat observations for the estimation of sea surface wind vector under severe weather conditions - art. no. C09023. Journal of Geophysical Research ( JGR ) - Oceans, 112(C9), NIL_49-NIL_66. Publisher's official version : http://doi.org/10.1029/2007JC004163 , Open Access version : http://archimer.ifremer.fr/doc/00000/6393/