周晓霞,丁一汇,王盘兴. 2008. 夏季亚洲季风区的水汽输送及其对中国降水的影响[J]. 气象学报, 66(1):59-70, doi:10.11676/qxxb2008.006
夏季亚洲季风区的水汽输送及其对中国降水的影响
Moisture transpotr in Asian summer monsoon region and its relationship withsummer precipitation in China
投稿时间:2006-03-21  修订日期:2006-06-22
DOI:10.11676/qxxb2008.006
中文关键词:  亚洲季风区,水汽输送,中国夏季降水
英文关键词:Asian monsoon region, Moisture transport, China summer precipitation.
基金项目:国家重点基础研究发展计划“973”计划,“亚印太交汇区”海气相互作用及其对中国短期气候的影响——课题四:亚洲季风区水分循环和变异机制(2006CB403604)
作者单位
周晓霞 中国气象局气候研究开放实验室,北京100081
南京信息工程大学大气科学系,南京210044 
丁一汇 国家气候中心,北京100081 
王盘兴 南京信息工程大学大气科学系,南京210044 
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中文摘要:
      利用1948—2005年NCEP/NCAR逐日及月平均资料,研究了亚洲季风区水汽输送的气候特征及其与中国夏季降水的关系。结果表明:(1)亚洲夏季风区不论在纬向和经向输送上,都表现了其独特性。夏季亚洲季风区为强大的水汽汇,东亚大陆和印度季风区均有较强的水汽辐合中心。(2)大部分水汽集中在对流层中下层,主要来自印度季风区,而对于对流层中上层,则以西太平洋和中纬西风带的输送为主。(3)印度季风在5—7月纬向向东的输送加强,东亚季风在6—7月以经向向北的输送加强为主,7月达最强,8到9月季风减弱直至结束。亚洲季风区青藏高原南侧的南支西风对东亚的水汽输送有重要作用,表现为春季最强,中高纬和热带西风输送变化同步,在盛夏达到最大,7月热带西风输送的水汽占三支水汽总输送的80%左右,来自中高纬地区的水汽约占18%。(4)季风爆发后,大量水汽从南半球输送到亚洲季风区。水汽辐合增加最大在孟加拉湾、中南半岛和南海地区,中国大陆的水汽主要经南海北边界输入。(5)水汽输送的北进与雨带的北推相一致。水汽输送场的时空分析表明,EOF1和EOF2分别代表强弱季风年的水汽输送特征。EOF1反映了东亚季风区一致的异常向北输送,并且在1970年代末发生了明显减弱。它与华北降水相关密切,表明自1980年代以来东亚季风向北水汽输送的减弱是华北干旱的主要原因。EOF2的主要特征是从1980年代之后,来自东北和西南的异常水汽在长江流域辐合,导致长江流域降水增多。相关分析表明,东亚夏季风在年代际尺度上的变化对此起了重要作用。
英文摘要:
      The characteristics of moisture transport over Asian summer monsoon region and its relationship with China summer precipitation are examined by a variety of statistical methods using NCEP-NCAR reanalysis data for 1948-2005. Results show that: 1)The zonal-mean moisture transport in Asian monsoon region is unique because of the monsoon activities. Asian summer monsoon region is a dominant moisture sink during summer. Both the Indian monsoon and East Asian monsoon areas have their convergence center, respectively. 2) Most column moisture congregates in the lower troposphere primarily from the Bay of Bengal and in the mid and upper layers, the vapor flux comes from mid-latitude westerlies as well as the tropical West Pacific Ocean. 3)The moisture fluxes by Indian monsoon enhance from May to July mostly in zonal transport while those by East Asian monsoon intensify mainly in meridional transport from June to July. Both reach their maxima in July and then decrease from August. The sub-tropical westerly moisture fluxes south to the Tibet Plateau across 90°E is strong in spring, while the mid-high latitude and tropical westerly vapor transfer change in phase and increase from January to July. The tropical westerly transport accounts for about 80% of the total moisture transport in July and only 18% from mid-high latitudes. 4)The moisture transfer and budgets over Asian monsoon region undergo a substantial change after the South China Sea monsoon onset, especially in the Bay of Bengal and IndoChina peninsula and the South China Sea. The northern boundary of South China Sea is of great importance in providing abundant moisture for China continent during summer. 5)The northward progress of the moisture transfer coincides with the seasonal march of the rainbelts very well. The EOF1 of moisture transport field basically depicts the consistent northward transport anomaly with an obvious decreasing trend over East Asian monsoon region from 1951 to 2005.Further analyses suggest that this trend owing to the weakness of East Asian Summer monsoon is largely responsible for the decline of rainfall over North China. The EOF2 reveals that moisture flux convergence from northeast and southwest over Yangtze River Valley shows a slight increasing tendent from 1980’s and it is consistent with the fact of more frequently occurred heavy rainfall over there.The correlation analyses denote that the interdecadal variation of the East Asian summer monsoon accounts for the main part of the variation.
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