全球典型干湿变化区域水汽收支与降水变化的对比分析

Comparative Analysis of Relationship between Moisture Budget and Precipitation Changes among Global Significantly Wetting/Drying Regions

利用NCEP/NCAR再分析资料和CRU降水数据,分析了1948-2009年全球典型干湿变化区域水汽收支的时间变化特征,并比较了这些区域净水汽收支、可降水量与降水的变化关系。结果表明:(1)亚洲大陆东部、非洲大陆年水汽收支显著减少,而北美大陆显著增加,三个地区的净水汽收支变化与区域的干、湿变化特征相一致;(2)对于亚洲大陆东部,春、夏、秋季和年水汽收支状况较一致,即经向收支和净收支均呈显著减少趋势,纬向收支均呈增加趋势。冬季与年平均状况有所不同,三种收支都增加;(3)在北美大陆,夏、秋和冬季的水汽收支趋势与年水汽收支趋势基本一致,即经向收支增加,纬向收支减少,净收支增加;仅春季经向收支减少,纬向收支增加;(4)在非洲大陆,四个季节的纬向收支和净收支均减小,纬向水汽的变化主导着净水汽的变化;与年变化特征不同的是,春、夏季的经向收支减少;(5)近几十年来,在亚洲大陆东部和非洲大陆,伴随着各季及年降水的减少,同期净水汽收支和可降水量也随着减少,且相关显著。在北美大陆,伴随着各季及年降水的增加,同期净收支也随着增加,且相关也较显著。值得注意的是,北美大陆的可降水量与降水没有很好的相关性。

Changing tendency of moisture budget(MB) of global significantly wetting/drying regions during1948-2009 and relation between net moisture budget(NMB) and precipitation(P),as well as between precipitable water vapor(PWV) and P were analysed utilizing NCEP/NCAR reanalysis data and CRU(Climatic Research Unit) precipitation data.During the research,statistical methods,such as linear regression,lowpass filtering and correlation analysis,were used.Results show that:(1) Annual NMB over both East Asian continent(EA) and African continent(A) had an obviously decreasing trend,comparing to increasing trend over North American continent(NA).And changes of NMB were in accord with regional arid/wet changing characteristics over all of these three areas;(2) Over EA,spring,summer,autumn and annual mean MB were consistent,that was,meridional moisture budget(MMB) and NMB decreased significantly;zonal moisture budget(ZMB) showed an increasing trend.However,in winter,NMB,MMB and ZMB all increased;(3) Over NA,MB in summer,autumn and winter had a similar trend to annual MB,that was,MMB and NMB increased,but ZMB decreased;only in spring,MMB decreased,but ZMB increased;(4) Over A,ZMB and NMB in all the four seasons reduced,and changes of ZMB dominated that of NMB in this region;and different to annual variation,MMB in spring and summer decreased;(5)In recent decades,over EA and A,with reduction of seasonal and annual P,NMB and PWV in the same period reduced,along with correlation coefficients between NMB and P,as well as between PWV and P,being significant.Over NA,along with the increase in seasonal and annual P,NMB also increased with correlation being significant.It is noteworthy that PWV and P weren't in coincident over NA.Its mechanism is still unclear,which requires an addition of numerical models or other methods for further study.