Seasonal Forecasts for Asia: Global Model Experiments

Abstract

Since Sept. 26, 1997, the Scripps Experimental Climate Prediction Center (ECPC) has been making experimental, near real-time seasonal global forecasts with the National Centers for Environmental Predication (NCEP) global spectral model used for reanalysis. Images of these forecasts — at seasonal time scales — are provided on the World Wide Web, and digital experimental forecast products are made available to interested researchers. In particular, these forecasts are now being used to drive a regional prediction model and various application models at National Taiwan University (NTU). Are these forecasts useful for Asia? What improvements could be made? The purpose of this paper is to describe briefly the global forecast and validating analysis system, various biases and errors in the forecasts for the Asia region, and the significance of the seasonal Forecast over Asia, using two years of forecasts form October 1997 through October 1999. In particular, near-surface meteorological parameters, including temperature, precipitation, soil moisture, relative humidity, wind speed, and a fire weather index (a nonlinear combination of temperature, wind speed, and relative humidity) are skillful at weekly to seasonal time scales over much of the Asia region. Still, there are many improvements that can be made. The purpose of this paper is to provide a baseline for further development of the global model as well as various regional and specialized application models.

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