Ocean models are generally forced by synthetic (global) NWP model wind fields. It has however been shown that these fields lack mesoscale wind structures on scales below 500 km, i.e., on the ocean eddy scale. Also, compared to wind observations, NWP model wind fields have persistent wind direction biases and lack response to SST gradients or air-sea temperature difference.
Based on Kolmogorov turbulence theory it is well known that the wind in the boundary layer has a kinetic energy spectrum with wave number power slope of −5/3 in mesoscales. It is a very important property and preservation of this property in dynamical models can significantly improve ocean forcing.
The scatterometers nowadays provide a very accurate measurement of wind over the ocean and the retrieved winds contain the mesoscale structure consistent with the Kolmogorov theory. The scatterometer winds are available over the ocean only at a specific time and at a specific location. The goal of this project is to propagate the physically correct scatterometer winds both in time and space and provide a uniform wind forcing over the ocean.
For the spatial and temporal propagation of the scatterometer winds we use a simplified dynamical model of Boussinesq type which is forced by ECMWF pressure field. The scatterometer winds are incorporated into the model by using a simple nudging approach.
D Harutyunyan, A Stoffelen. Spatial and Temporal Propagation of Scatterometer Winds
2011, KNMI, 2011