东亚夏季风强弱年物理量的逐候变化及其对松嫩流域降水的影响

Every Pentad Variation of Physical Quantities and its lmpact on the Precipitation over the Song-Nen River Valley in the Summer Monsoon of East Asia Strong and Weak Years

用施能定义的东亚夏季风指数,分别找出典型夏季风强弱年1961和1980年,分析水平风速、假相当位温、高度等的逐候变化特征与盛夏季节松嫩流域逐候降水量的关系。分析表明:东亚夏季风强弱对松嫩流域盛夏降水量有显著影响。在强夏季风年,较大的南风、较高的假相当位温、较深的东亚大槽使降水持续偏多。同时还发现,无论夏季风强弱,假相当位温高值总是与多降水相联系。

Applying the index of -the summer mon soon of East -Asia defined by Shineng,summer monsoon strong and weak years including 1961and 1980are selected respectively,and the relationship between every pentad midsummer precipitation over the Song -Nen river valley and every variable feature of horizontal wind velocity,geopotential height field,pseudo -potential temperature is analyzed.Results show that the and w eak East -Asia summer monsoon affect the midsummer precipitation over the Song -Nen river valley,and in the strong summer monsoon year,the high er southern wind,higher pseudo -potential temperature and deeper East -Asia trough bring about the pre cipitation above normal.The higher value of pseudo -potential temper-ature is always related closely to th e precipitation above normal in summer monsoon strong and weak years.