STUDIES ON RELATIONSHIPS AMONG SNOW COVER WINTER OVER THE TIBETAN PLATEAU AND DRO UGHTS/FLOODS DURING MEIYU SEASON IN THE MIDDLE AND LOWER REACHES OF THE YANGTZE RIVER AS WELL AS ATMOSPHERE/OCEAN

Based on the integrated analysis for abnormal snow day, snow depth and snow covered area data in Tibetan Plateau in winter, as well as the comprehensive assessment for flood/drought in summer in the middle and lower reaches of Yangtze River valley by using the indices such as percentage of monthly precipitation anomalies, Mei-yu period length and zindex, correlation analysis shows the very positive correlation between them.The Northern Hemisphere anomlous 500-Pa geopotential height, the anomalous outgoing longwave radiation and the anomalous sea surface temperatures in the same time averaged both for the more-snow years and for less-snow years in Tibetan Plateau are analyzed. The associati on between ENSO and Summer Asia Monsoon is also revealed. Result shows that the Northern Hemisphere general circulation are remarkably different between the more-snow years and less-snow years in Tibetan Plateau. A primary flood/drought physical process model is achieved, which has demonstrated the probably association among the snow, atmosphere, ocean and the following summer rainband in the middle and lower reaches of Yangtze River valley. This model can provide the clues for short-term climate monitoring and prediction.