verification of scatterometer winds

Since several centres produce scatterometer wind products, user guidance would be useful to direct users to the most appropriate product for their application. Moreover, for further product development advanced analysis tools are needed to determine product characteristics and improvement. Since not all scatterometer data sets have the same Quality Control (QC) and coverage, sampling may play a distinct role in product assessment. Another complication in product comparison is in its smoothness. Smooth products will verify well against NWP model fields, but relatively poor against in situ measurements. Here, we elaborate two tools for product comparison. The first is dual product collocation with a representative set of reference data; in the current case from a buoy network. The second tool exists in spectral analysis of the spatial structures in the scatterometer products. Our analyses show that ASCAT scatterometer winds reveal detailed spatial wind characteristics and show a unprecedented verification with buoy data. Moreover, the KNMI SeaWinds product at 25-km sampling shows better verification against buoys than the NOAA SeaWinds product over a common data set of points. While the KNMI SeaWinds QC, when applied to the NOAA SeaWinds product, shows a clear improved buoy verification, NOAA SeaWinds QC has a smaller effect on the buoy verification of the KNMI SeaWinds product. Buoy verification and spectral analysis as presented in this paper are indispensible tools in the further development of the KNMI scatterometer products.