Air-sea interaction studies require surface fluxes of momentum, heat and moisture. This research will determine these fluxes by using a sophisticated physical initialization procedure that invokes detailed "observed" rain which is based on a mix of SSMI (Special Sensor Microwave Instruments), OLR (Outgoing Longwave Radiation), and rain-gauge data sets. The powerful rainfall algorithm calibrates the rain rates for ground truth as the daily fields are produced. The fluxes, in turn, are obtained by using a series of reverse physical parameterization algorithms within the initialization of a high resolution numerical prediction model. This physical initialization technique is one of the most powerful and consistent procedures for determining surface fluxes. Fluxes for the western Pacific warm pool region will be determined for a five year period starting in January 1987. In addition, this research will include a detailed comparison and critical evaluation of the following fluxes obtained during the TOGA COARE observation program: a) Bulk aerodynamic fluxes, b) Fluxes based on surface similarity theory and corrected as needed for low/high wind speeds and the free convection limit, c) Fluxes based on the physical initialization technique discussed above, d) Fluxes based on the NMC (National Meteorological Center) operation forecast model, e) Fluxes based on the ECMWF (European Centre for Medium-range Weather Forecasting) operational forecast model. This research is important because it is one of the TOGA/TOGA COARE studies that investigates air-sea interactions, particularly surface fluxes, in the context of the numerical representation of the physical processes that impact climate variability in an especially climate sensitive region of the world, the western Pacific Ocean, the field site of the TOGA COARE program.