Abstract:
Previous study comes to the conclusion: based on the anomalies of t he South Asi an High (SAH), anomaly of 100hPa geopotential height and 100hPa circulation over tropical and subtropical region in previous year, we can predict precipitation anomaly in the Yangtze River Valley and North China. To test its validity, a ser ies of experiments have been designed and operated. The experiments include cont rolled experiment, sensible experiment (which has added anomalies into 100hPa geopotential height and wind field) and four composite experiments. Experiments ba sed on the composed initial field such as EPR CF, EPRCD, EPRHF, and EPRHD , canreproduce the floods or droughts in the Yangtze River Valley and North China. It suggests that anomalies of South Asian High, 100hPa geopotential height and c irculation over tropical and subtropical region can probably imply summer precip itation anomalies in the two regions. Sensible experiment results show that anom alies of the SAH, 100hPa geopotential height and wind field in previous period i s a signal of floods or droughts the following summer in the Yangtze River Valle y and North China. And it is also one of the factors that have impact on summer precipitation anomaly in the two regions. Positive anomaly of 100hPa geopotentia l height and the anomalous intensifying of the SAH and southwest flow will induc e floods in the Yangtze River Valley and droughts in North China; while negative anomaly of 100hPa geopotential height and anomalous weakening of the SAH and so uthwest flow will induce droughts in the Yangtze River Valley and floods in Nort h China.