The Impacts of Radiation Schemes on the GRAPES Global Model
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Abstract
Radiation process is one of the most important physical parameterization schemes in the medium-range and climate models. Concerning the characteristics of non-hydrostatic and semi-Lagrangian calculation, a set of sensitive experiments has been conducted in order to find a more suitable radiation scheme to GRAPES global model. The used radiation schemes include RRTM long wave and Goddard's short wave schemes from the WRF (Weather Research and Forecasting) model, as well as ECMWF's radiation scheme. The results show that ECMWF's radiation scheme is more suitable to the GRAPES global model, and 30-day averaged anomaly correlation coefficient for 500-hPa geopotential height in the Northern Hemisphere increases about 2%, compared to the WRF scheme. Also a pressure and a temperature correction schemes have been incorporated to the radiation process in order to enhance its computational stability. The 120-hour forecast to the typhoon Haitang indicates that the subtropical height and typhoon described by the correction schemes are closer to the analysis, and 31-day averaged anomaly correlation coefficient for 500-hPa geopotential height in the Northern Hemisphere is improved obviously.
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