Verification of GRAPES_Meso V3.0 Model Forecast Results

The rainfall, temperature, height and wind forecast products of GRAPES_Meso model (V3.0), which is mesoscale model of the new generation multiple time scale numerical weather prediction system, are verified by operational statistical verification methods from March 2008 to February 2009. Dichotomous and continuous forecast verification methods for deterministic forecast model recommended by World Meteorological Organization or Chinese Meteorological Administration are employed. The verification results show the rainfall forecast of V3.0 model is better than V2.5 model. The annual mean TS of rainfall forecast is improved for all five grades and is higher than that of V2.5 model clearly for four seasons mean, all months mean of a year, except for 48-hour moderate rain and storm rain of autumn and winter. The forecasted rainfall of V3.0 model is mainly greater than observed rainfall, especially for moderate to heavy rain. The simulated distribution of the season mean raining rate is much more similar to the observed patterns. For the 24-hour forecast of eastern China in autumn and winter, rainfall is almost no longer underestimated. The forecast performance of location and intensity of strong rainfall center for spring and summer has also been improved, but the amount of 48-hour rainfall is obviously overestimated comparing to observation, shown clearly through the figures of daily mean rain rate time series. Meanwhile, the developing trend and intensity forecast of strong rainfall processes is better than that of V2.5 model for most time of the year. The height, temperature and wind forecasts of the upper prognostic forecast have made remarkable progresses especially for 500 hPa height forecast, 500 hPa wind forecast, and 48 hour 850 hPa wind forecast. However, the forecast of 24-hour low level temperature and height in summer are hardly improved, so the model still need more progresses especially in rainy season. For other seasons, the forecast of temperature and wind in low level atmosphere is fairly good.