IMPACT OF SCATTEROMETER WINDS ON HYDROLOGIC FORCING AND CONVECTIVE HEATING THROUGH SURFACE DIVERGENCE

One of the difficulties in estimating atmospheric heat and moisture bu dgets lies in resolving the near-surface heat and moisture convergence and vertical velocities, each of which is highly dependent on the div ergence of the surface wind. A kinematic approach is proposed to utili ze scatterometer winds to improve the estimate of surface wind diverge nce, the omega profile, and, therefore, estimates of the hydrologic fo rcing and convective heating over the tropical ocean. Improvements in these estimates over those obtained using analyses of the European Cen tre for Medium-Range Weather Forecasts (ECMWF) alone are found when th e ERS-1 scatterometer ground tracks passed over the TOGA COARE intensi ve flux array. The spatial patterns of precipitation estimated from GM S IR temperatures and radar reflectivities agree better with the diver gence fields derived from the ERS-1 scatterometer winds than with thos e derived from either ECMWF or rawinsonde winds. The use of ERS-1 surf ace winds also changes the omega profiles throughout the atmosphere. T he heat and moisture budgets are sensitive to vertical velocity and ar e, therefore, significantly affected by the inclusion of scatterometer winds. Precipitation estimates from GMS IR temperatures are found to agree better with those estimated from budget residuals computed using scatterometer winds.