An analysis scheme for determination of true surface winds at sea from ship synoptic wind and pressure observations

For oceanographic studies, a high resolution description of the wind field at the sea surface is required. In order to estimate the air-sea interaction fluxes correctly, it is important that the derived wind field has the characteristics of actual surface winds. Ship synoptic observations are at irregular positions, while applications require boundary conditions at a regular grid. The problem is solved by locally fitting a second-order pressure surface to both wind and pressure observations, with the aid of a boundary-layer formulation. For the ship synoptic data available via GTS for the North Atlantic Ocean, spatial resolution, as expressed by an equivalent filter half-width, is 220 km, considerably improved compared to typical data assimilation schemes used in numerical forecast models.