Intercomparison of OSCAT Winds With Numerical-Model-Generated Winds

Abstract

Subsequent to the launch of an ocean scatterometer onboard the Oceansat-2 satellite, hereby referred to as OSCAT, on September 23, 2009, the nine-month period from November 2009 to July 2010 was the validation phase for the retrieved ocean surface winds. This letter focuses on one section of the validation campaign, where the validation study for OSCAT winds with European Centre for Medium-Range Weather Forecasts (ECMWF) and National Centers for Environmental Prediction (NCEP) analyses is carried out. It is found that, in the 4–24-m/s range of wind speed, the rms error in OSCAT wind speed with ECMWF analysis is 1.4 m/s while that with NCEP analysis is 1.7 m/s. In the case of retrieved wind direction, the rms error is 17.2 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex> </formula> with ECMWF analyses, while that for NCEP is 18.8 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex> </formula> . These statistics are well within the mission goal of 2-m/s accuracy in wind speed and 20 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> in wind directions. This letter discusses the comparison results for different geographical regions and wind speed ranges.