Atmospheric Water Vapor Transport Associated with Two Decadal Rainfall Shifts over East China
Atmospheric Water Vapor Transport Associated with Two Decadal Rainfall Shifts over East China
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DOI：
10.2151/jmsj.2012-501
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发表时间：
2012
影响因子：
3.1
通讯作者：
Xiuzhen Li;Z. Wen;Wen Zhou;Dongxiao Wang
中科院分区：
文献类型：
--
作者：
Xiuzhen Li;Z. Wen;Wen Zhou;Dongxiao Wang
利用观测降水和欧洲中期天气预报中心 (ECMWF) 40 年再分析 (ERA-40) 数据集，研究了与 1978/79 年和 1992/93 年华东两次十年夏季降雨变化相关的大气水汽输送和水分收支。 1978/79年以后，江淮流域（YH）夏季降水急剧增加，华南（SC）和华北（NC）夏季降水减少。与降雨变化相关，华东地区南风水汽输送减弱； SC地区存在反气旋性水汽环流异常，且水汽辐合减弱；来自南卡罗来纳州西部的异常水汽在YH与来自北卡罗来纳州西部的异常水汽汇合，然后向东转向，而不是向北到达北卡罗来纳州。 1992/93 年之后，南卡罗来纳州的降雨量急剧增加。这与南方和北方的两次异常反气旋性水汽环流的西北和西南外流在南华上空汇合密切相关。在这两次气候变化过程中，主要位于对流层低层的经向水汽通量的变化对YH、SC和NC的降水异常起到了重要作用。水汽输送异常主要受扰动风场控制，而非扰动水汽场。
The atmospheric water vapor transport and moisture budget associated with two decadal summer rainfall shifts in 1978/79 and 1992/93 over East China were investigated using observational precipitation and the European Centre for Medium-Range Weather Forecasts (ECMWF) 40 Years Re-Analysis (ERA-40) dataset. After 1978/79, summer precipitation increased abruptly in the Yangtze-Huaihe River valley (YH) but decreased in South China (SC) and North China (NC). Associated with this rainfall shift, southerly water vapor transport over East China was weakened; an anticyclonic moisture circulation anomaly along with decreasing moisture convergence existed in SC; abnormal water vapor from western SC converged in YH with that from western NC, then turned eastward, instead of northward to NC. After 1992/93, rainfall over SC increased dramatically. This is closely related to two abnormal anticyclonic moisture circulations to the south and the north when their northwesterly and southwesterly outflows converged over SC. During these two regime shifts, it was the variation of meridional water vapor flux, located mainly in the lower troposphere, which played an important role in the rainfall anomalies over YH, SC, and NC. The water vapor transport anomalies were mainly controlled by the disturbance wind field instead of the disturbance moisture field.