The Calibration of ERS-1 Satellite Scatterometer Winds

Abstract

During the period mid-September to mid-December 1991, the RENE-91 campaign took place off the of Norway. Extensive in situ measurements of winds and waves were made from several platforms in order to calibrate thew parameters derived from radar instruments on board the ERS-1 satellite. Over several weeks the U.K. Meteorological Research Flight C-130 aircraft measured low-level winds beneath the scatterometer swath. Together with data from other aircraft, ships, and buoys, an objective analysis scheme was used to form the bet climate of the local wind field for a quick-look comparison with the ERS-1 scatterometer data, and later to determine an optimized relationship between the scatteromete's backscatter values and the local wind vector. The wind fields have also been used to verify the performances of various candidate C-band radar backscatter models in retrieving wind vectors from the original ERS-1 scatterometer data. This analysis showed that the prelaunch model could be significantly improved upon, and a new model has been selected for operational fast delivery processing. Typically, the scatterometer accuracy is about, or better than, the instrument specification of 2 m s?1 and 20° rms when compared with analyzed RENE-91 or operational global NWP wind fields.