Level 2 OCN Ocean Wind Field (OWI) Component
The OWI component is a ground range gridded estimate of the surface wind speed and direction at 10 m above the surface, derived from SM, IW or EW modes.
The OWI component contains a set of wind vectors for each processed Level-1 input product.The norm is wind speed in m/s and the argument is wind direction in degN.
The spatial resolution of the SAR wind speed is 1km for SM, IW and EW modes and 20 km for WV mode. This is lower than the resolution of the original Level-1 product and depends on the level of uncorrelated speckle noise. The resolution of the SAR wind direction is lower than the resolution of the SAR wind speed and depends on the source of wind direction used.
The SAR wind retrieval geophysical model functions are designed to retrieve the equivalent neutral stability wind speed at a height of 10 m above the ocean surface. The model responds to changes in roughness at the ocean surface, but cannot respond directly to changes in wind speed due to atmosphericstratification. The equivalent neutral stability wind speed is defined as the mean wind speed that would be observed if there was neutral atmospheric stratification.
For WV mode, the wind information comes from the ECMWF atmospheric model and is reported in the OSW component, while for SM, IW and EW it is derived from the Level-1 data and reported in the OWI component.