Validation of ASCAT 12.5-km winds, version 1.3

The Ocean and Sea Ice Satellite Application Facility (OSI SAF) delivers an operational level 2 wind product in near-real time, based on the ASCAT level 1 product with 25-km Wind Vector Cell (WVC) spacing from EUMETSAT. However, since backscatter measurements of up to 70 km away from each WVC centre are used in the spatial averaging, the spatial resolution of the product is only approximately 50 km.

EUMETSAT also produces a level 1 product with 12.5-km WVC spacing that has a resolution of approximately 25 km. Since the backscatter values of the 12.5-km product are averaged over fewer full resolution backscatter measurements, it can be expected that it contains more noise. On the other hand, the higher resolution is profitable since small-scale meteorological phenomena can be resolved that are not visible in the 25-km product.

The 25-km wind product has been subject to much validation work already in the OSI SAF project. This report is an extension to the existing work and it describes the validation of the 12.5-km wind product. The 12.5-km and 25-km products are compared with in situ wind data from moored buoys and also a comparison of the two products is made. It appears that the 12.5-km product compares even slightly better to the buoy winds than the 25-km product does. The 25-km and 12.5-km winds compare very well with each other.