摘要
采用1983—2002年NCEP/NCAR再分析资料和我国660站降水资料,对我国东部季风湿润区夏季水汽收支变化与大气环流和我国降水异常特征的关系进行研究。结果表明:20世纪80—90年代夏季水汽收支时间序列表现出明显的年代际变化增加趋势,与降水时间序列的相关系数为0.71;水汽收支高值、低值年代不仅能够指示季风湿润区经向风的异常变化,还能够指示东亚夏季风的强弱和降水异常变化。合成的水汽输送年代际异常在东亚—西太平洋区表现为4个异常环流,异常水汽通量辐合区位于长江流域及以南地区。水汽收支高值年代,亚洲大陆高纬度地区低压偏弱,大陆表面温度及西太平洋海温偏高,我国东部沿海盛行异常偏南风,低层气流辐合、高层气流辐散强,垂直上升运动强烈;低值年代则相反。合成的经向水汽收支占总收支的71.3%,合成的异常降水量最大达100 mm以上。
Using monthly means of NCAR/ NCEP reanalysis datasets and rainfall data from 660 surface stations in China, a water budgets time series over the monsoon wetness region in Eastern China is calculated by a water vapor transport method for the period from 1983 to 2002, referring to changes in inter-decadal varia bitity of water budgets associated with the anomalous atmospheric circulations and precipitation in the monsoon wetness region of Eastern China. Relationships between the water budget index and the variabili- ty of the atmospheric circulation and rainfall in China are examined. The results show that the summer wa- ter budget time series displays the variability on the inter decadal scale from the 1980s to the 1990s in the region. The correlation coefficient is 0. 71 between the water budgets and regional average precipitation and decreases to 0.55 after removing the trends. The index reflects the variations of the meridional winds anomalies and indicates an intensity of summer monsoon and an anomaly of rainfall along the valleys in the monsoon wetness region of Eastern China. The anomalous water vapor transport is affected by four anom alous circulations： The anomalous cyclonic circulation between 20°N and 30°N over the Eastern China, and the anomalous anti-cyclonic circulations between 40°N and 60°N over East Asian continent, between 18°N and 30°N over the west Pacific, and between 5°N and 20°N over the Bay of Bengal. Anomalous moisture flux convergence appears in the south of the Yangtze. Corresponding to the higher-index value decades, the low pressure centering in Mongolia is weaker and the surface temperature, sea surface temperature, the convergence in lower troposphere and divergence in upper troposphere are generally stronger in East A- sia and the western north Pacific. Meanwhile, the southerly wind anomalies are prevailing in the eastern coast of China. This anomaly intensifies upward motion over the south mainland of China and drives the water vapor transport from South China Se
出处
《应用气象学报》
CSCD
北大核心
2013年第1期12-22,共11页
Journal of Applied Meteorological Science
基金
国家重点基础研究发展计划项目(2009CB421404)
关键词
水汽收支
降水
大气环流
年代际变化
water budget
rainfall
atmospheric circulation
inter-decadal variability
