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The current operational World Weather Watch over the tropical latitudes exhibits large data gaps. This paper proposes a detailed physical initialization procedure where the combined use of the World Weather Watch and detailed 'satellite data sets are used to enhance the definition of initial surface fluxes of water vapor and sensible heat, the initial rainfall rates and the earth's radiation budget. The satellite radiances are used to unify the physical initializations of the fluxes, rainfall, and the clouds. This is carried out using a Newtonian relaxation during a•pre integration phase between day -1 and day 0 where the fluxes, the rainfall rates, and the cloud distributions provide a consistent humidity analysis and a spin up of the diabatic heating and the divergent circulations. A comparison of medium range forecasts from a control experiment (that utilizes the standard nonlinear normal mode initialization, with physics, at day 0) with an experiment based on the unified physical initialization is carried out to demonstrate the effective enhancement of the World Weather Watch over the tropics by the proposed method. These experiments are carried out with a global spectral model which is run at a resolution of 106 wave triangular truncation.

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Following our recent study on physical initialization for tropical prediction using rain rates based on outgoing long‐wave radiation, the present study demonstrates a major improvement from the use of microwave radiance based rain rates. A rain rate algorithm is used on the data from a special sensor microwave instrument (SSM/1). The initialization, as before, uses a reverse surface similarity theory, a reverse cumulus parameterization algorithm and a bisection method to minimize the difference between satellite‐based and the model‐based outgoing long‐wave radiation. These are invoked within a preforecast Newtonian relaxation phase of the initialization. These tests are carried out with a high‐resolution global spectral model. The impact of the initialization on forecast is tested for a complex triple typhoon scenario over the Western Pacific Ocean during September 1987. A major impact from the inclusion of the SSM/I is demonstrated. Also addressed are the spin‐up issues related to the typhoon structure and the improved water budget from the physical initialization.