青藏高原季节冻融过程与东亚大气环流关系的研究

STUDY ON RELATIONSHIP BETWEEN THE FROZEN-THAW PROCESS IN QINGHAI-XIZANG PLATEAU AND CIRCULATION IN EAST-ASIA

利用青藏高原 46个气象站的最大冻土深度观测资料、中国 16 0个气象站降水资料和NCAR NCEP资料 ,对青藏高原冻土的季节性冻融过程进行合成分析 ,发现青藏高原土壤的季节冻融过程对青藏高原上空及东亚大气环流有显著的影响 ,在高原最大冻土深度较小的年份中 ,7月份 ,南亚高压强且偏西 ,5 0 0hPa印度低压强 ,西太平洋副热带高压弱且偏东 ,高原南部的东风较强 ;最大冻土深度较大的年份 ,南亚高压弱且偏东 ,印度低压弱 ,西太平洋副热带高压强且偏西 .在不同的冻融年份 ,85 0hPa上纬向风的差异显著区反映了西南季风的活动 .最大冻土深度与中国夏季 ( 7月份 )降水有 3条显著相关带 ,雨带的分布与中国夏季平均雨带相吻合 .由此 ,青藏高原季节冻融过程引起的水热变化是影响东亚气候的一个重要外源 .

The relationship between the frozen-thaw process in Qinghai-Xizang Plateau and the East Asia circulation is studied by using the data of the maximum frozen soil depth at 64 stations during 1961～1999 in Qinghai-Xizang plateau and precipitation of 160 stations ove China. The results shows that the seasonal frozen-thaw process in Qinghai-Xizang plateau strongly affects the circulation over the plateau and East Asia. In July when the frozen soil depth of Qinghai-Xizang plateau is lower the South Asian high is stronger and moves to west in location, Indian cyclone is lower, subtropics high of west Pacific is weaker and moves to east in location and east winds in strong. The differences of zonal winds in 850hPa in different years the activity of west-southern monsoon. There are 3 belts the correlation between frozen the soil depth and precipitation in July, and these belts are same in location as the precipitation distribution in July over China. Therefore, the changes of moisture and heat from frozen-thaw process in Qinghai-Xizang Plateau is an important outside heat source, which influences East Asia climate.