Exploring the Characteristics of high-resolution Ocean Surface Winds with Doppler Scatterometry

The wind at the ocean’s surface is a fundamental climate variable responsible for me-48 diating the exchange of heat, carbon dioxide, and other tracers between the atmosphere49 and the ocean. Recent high-resolution modeling studies suggest that these exchanges are50 strongest at small scales where the wind is not well characterized, and that at these scales,51 the wind is often modified by air-sea coupling. Using a Ka-band Doppler scatterome-52 ter during the NASA Submesoscale Ocean Dynamics Experiment, we mapped 2D ocean53 winds and currents on scales between 200 m and 100 km to explore their characteristics54 and interactions. This paper introduces the high level results from DopplerScatt wind55 measurements, specifically: validation, spatial features, energy spectra, and divergence/vorticity,56 all in the context of underlying DopplerScatt surface current observations. Our results57 find large deviations from the classical Nastrom-Gage -5/3 spectrum depending on the58 underlying physical process. In some cases, these processes are associated with distinct59 atmospheric phenomena (like atmospheric rolls and convection), while in others they are60 associated with a signature of wind-current interactions. We also frequently observed strong,61 scale-dependent wind divergence, implying possible small-scale vertical motion in the at-62 mosphere. Taken together, these results do not support either Kolmogorov isotropic tur-63 bulence theory due to observed anisotropy nor two dimensional turbulence due to sig-64 nificant small-scale divergence.