Ocean wave effects on the retrieved wind field from the scatterometer

The scatterometer is a kind of non-nadir real aperture radar (RAR), which can estimate the wind field of sea surface based on geophysical model function (GMF). GMF describes the empirical relation between the wind field and the sea surface roughness characterized by sigma0. The wind wave is generated from the local wind and the swell wave is independent of the one. Based on the multi-scale scattering model, both wind wave and swell wave will modulate the sea surface roughness. This paper tries to find out the wave effects on wind field retrieval from scatterometer in swell and wind wave by the synchronous scatterometer and buoy data. The wind field data used in this paper are collected from Metop's Advanced Scatterometer (ASCAT) and buoy of NDBC. The NDBC buoy also provides the synchronous significant wave height (swh) and peak wavelength. From these data, the sea states are divided into swell and wind wave. Then the wave effects on retrieval are analyzed along with the swh and peak wavelength in each sea states. Results show that swell wave has a serious effect on the wind field retrieval. When the swh is higher than 1.5 m or the peak wavelength is lower than 230 m, the retrievals have significant errors