Assessment on Forecasting Skills of GFS Model for Two Persistent Rainfalls over Southern China
This study aims at assessing the predictability capacity of the Global Forecasting System (GFS) for the atmospheric circulation features and precipitation over East Asia during 11-31 July 2012 by using the GFS data and the extracted components of long wave and ultra long wave via the harmonic filtering. The results show that the GFS model can predict the mid and lower heights over East Asia with reliable lead time of 6 d, and up to 10 d for the higher heights. The predictability for long wave and ultra long wave components is more significant, of which the 5-8 wave band forecast is better than the 3-6 wave one in terms of the forecasting skill for height. However, the forecast result is reversed for the wind filed. In addition, the predictability of the model for the two persistent rainfalls maintains 8 d or so, and moreover it can tell the location of severe rainfall band ahead of 2 d. In general, the GFS model is stronger in forecasting the persistent precipitation process than the observed fields.