青藏高原冬季积雪异常和长江中下游主汛期旱涝及其与环流关系的研究

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

在对青藏高原冬季异常积雪资料进行了综合分析的基础上 ,用 3种方法对长江中下游的旱涝指标进行了综合评定 ,计算了高原积雪日数和深度资料与长江中下游 6～ 8月降水量之间的相关系数 ,结果表明 ,青藏高原冬季积雪异常与长江中下游流域的旱涝呈正相关关系 ,最大正相关区主要位于江南北部。通过对冬季北半球 50 0 h Pa高度场、OLR、SSTA资料的合成分析以及对夏季风指数的联系揭示表明 ,高原多雪和少雪所反映出的环流特征显著不同。讨论了异常积雪 -大气 -海洋 -雨带相互之间的可能联系 ,给出了一个初步与青藏高原冬季积雪相联系的长江中下游旱涝物理过程概念模型 ,进而为短期气候监测、预测提供参数线索。

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 z-index , 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 association 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 .