An improved sea state dependency for surface stress derived from in situ and remotely sensed winds

An improved model is developed for the dependency of surface turbulent stress on wave characteristics. Recent studies have used differences between satellite and in situ observations to gain insights into the physical processes that might be related to air-sea interaction. Both scatterometers and buoys provide very accurate measurements of wind speed. Differences between these measurements can be explained in terms of the different mechanisms to which the instruments respond. A physically-based flux model is developed herein. Prior results suggest that, the stress parameterizations, converting neutral equivalent wind speed to stress, applied to in situ observations differ subtlety from those that should be used for scatterometer-derived winds. These differences are due to water waves modifying the surface stress. This model provides a physical explanation of the observed differences, and provides a model for calculating stresses from scatterometer winds. The model is validated with recent in situ observations gathered under severe conditions. The model explains more wave-related variability in surface stress than previous models. (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.