Wind and Sea State Signatures in Wind Scatterometry: An analysis

This is the authors' abstract. We don't add key points for this paper.

A better understanding of how wind vectors are obtained in scatterometer retrievals may be useful to further develop wind scatterometry. Scatterometer ocean surface wind estimation involves air-sea and wind-wave interactions in rather diverse conditions. Curiously, scatterometer Geophysical Model Functions only depending on the wind vector prove very successful operationally, and sea state (ocean wave) parameters are not considered. It has been suggested in theories that, on one hand, wind-wave features are modulated by fetch or wave age and affected by longer waves or swells in terms of non-linear interactions and, on the other, direct wind-induced wave movements in the short ocean-wave spectrum, modulated by gusty winds. Though generally supported by limited sampling, some theories are associated with in-situ observations and laboratory experiments, scatterometer wind-wave-induced ocean roughness back-scattered signals can be associated with winds quite accurately, without considering the wave parameters. In this research, sea-state and wind variability parameters are specifically investigated for their effect on the scatterometer measurements and retrieved winds. Results confirm that the scatterometer backscatter values are generally not affected by non-local sea state and this is further discussed. Finally, an extreme wind case is provided for a better demonstration. The conclusions provide good references for the high-wind model modification and the next generation of scatterometers designed for simultaneous measurements of ocean surface wind, wave motion and ocean currents.