Seven Anomalous Synoptic Patterns of Regional Heavy Rain in Eastern China
The advantages of the anomalous synoptic systems over the traditional total ones in locating regional heavy rain (RHR) have been revealed by recent work of the anomalybased synoptic chart. Fortyone daily heavy rain cases in eastern China from 1998 are grouped into seven patterns based on the anomalous synoptic systems. The seven patterns of anomalous synoptic systems associated with regional heavy rain include the shear in South China, vortex in South China, reversed trough in South China, shear and trough along the Yangtze River, vortex along the Yangtze River, vortex in North China and vortex in Northeast China. The RHR can be well located by the negative regions of anomalous geopotential height, wind anomalous convergence combined with high moisture anomaly, which is evident from both the vertical crosssections and the 850 hPa horizontal distributions. This overcomes the shortage of traditional synoptic chart in which total field systems and high moisture regions do not collocate with heavy rain areas. It is recommended that anomalybased synoptic chart should be applied in the practice of shortterm and mediumrange forecasts by using the products of the current stateoftheart operational numerical weather models.