An Operational Medium-range Forecast Model for the Drought/Flood in the Middle and Lower Reaches of the Changjiang River
A double-level multi-factor synthetic analogue prediction model is given for the coming 10-day forecasting of the drought/flood in the middle and lower reaches of the Changjiang River in flood season. It takes into account of the following five predictors: the meridional transmission of geotropic west wind momentum,area index and location of the subtropical high in the west Pacific and the geopotential height filed at 500hPa level,the meridional temperature gradient and temperature field at 850hPa level. Compared with the former single-level analogue prediction model,it has more specific physical meaning and is more competent for the complex dynamic mechanics precipitation forecast. Five-year forecast experiment and operational application shows that this method has good performance in the medium-range tendency forecast for the drought/flood of the middle and lower reaches of the Changjiang River.