Atmospheric Wind Retrievals from Satellite Surface Winds and Temperature Sondings over the Middle and High Latitude Oceans

A technique that uses the satellite-based surface wind and temperature soundings for deriving the three-dimensional atmospheric wind fields is developed for climate studies over the oceans of the middle and high latitudes. In this technique, the thermal wind derived from the satellite soundings is added to the surface wind to obtain a first-guess, nonmass-conserved atmospheric wind profile. Then a Lagrange multiplier in a variational formalism is used to force the first-guess wind to conserve mass. Two mass conservation schemes are proposed. One is to use the mass flux conservation equation across a latitudinal wall as a constraint to retrieve the meridional wind first, and then the vertically-integrated mass conservation equation is used to infer the zonal wind. The zonal and meridional winds are obtained separately in this approach. The second scheme is to use the vertically-integrated mass conservation equation as a constraint to retrieve the zonal and meridional winds simultaneously from the first-guess field. Temperature soundings from the Television Infrared Observational Satellite (TIROS) Operational Vertical Sounder (TOVS) Pathfinder A dataset and a Special Sensor Microwave Imager (SSM/I) satellite-based surface wind field are used in deriving the wind fields. The two mass conservation schemes yields two different wind fields. They are compared with the ECMWF and NCAR/NCEP reanalyses and radiosonde observations over the Southern Ocean. It is indicated that the wind of the first scheme is closer to the reanalyses and radiosonde observations in most situations, while the second scheme yields a yearly-mean bias in the zonal wind field compared to the radiosonde observations. Differences between the two schemes and their differences from the reanalysis winds are discussed in detail.