大气科学2011，Vol.35Issue(6)：1105-1116,12.
我国冬季降水年际变化的主模态分析
Two Major Modes of the Wintertime Precipitation over China
摘要
Abstract
Based on the observed precipitation data from 160 China stations, the NCEP/NCAR reanalysis dataset and the sea surface temperature (SST) dataset from the Met Office Hadley Centre, this study investigates two major modes of wintertime precipitation over China through empirical orthogonal function (EOF) method and associated atmospheric circulation and SST through linear regression method. It reveals that the first two EOF modes account for 49. 6% and 17. 3% of the total variance, respectively, and can be well separated from the remaining modes. EOF1 reflects the strength of wintertime precipitation over southeastern China. The associated principal component(PCI) has significant interannual variability with 2-4 year period Its interdecadal variations suggest that the wintertime precipitation over southeastern China was below (above) normal before (after) the mid-1980s, and has a slight decreasing trend in recent years. EOF2 delineates an out-of-phase relationship between South China and the middle and lower reaches of the Yangtze River as well as the northern part of Xinjiang. The associated time series (PC2) also has a clear 2-4 year period and an interdecadal component, which experiences a clear trend towards its negative polarity from 1980 to 2005. Further analysis suggests that EOF1 is closely related to the El Nino-Southern Oscillation (ENSO) and the East Asian winter monsoon (EAWM). When warm (cold) ENSO is in its mature phase, the EAWM is weak (strong), the anomalous water vapor transport from the Bay of Bengal and the South China Sea converges (diverges) over southeastern China and favors more (less) precipitation in this region. The SST anomalies over the tropical eastern Pacific have significant relationship with the variation of EOF1, and may act as a potential predictor for this mode. The variation of EOF2 is closely associated with a barotropic wave train across the Eurasian continent originating from the North Atlantic, which can induce anomalous northerlies (southerlies) along the coasts of southeastern China. It then causes the divergence (convergence) of water vapor flux in the lower reaches of the Yangtze River and opposite condition in South China, and therefore favors a positive (negative) phase of EOF2. The SST anomalies around the Norwegian Sea over the North Atlantic have the closest relationship with the variations of EOF2, and may act as a potential predictor with a leading time of 7 months.关键词
冬季降水/年际变化/主模态/大气环流/海表面温度Key words
winter precipitation, interannual variation, major modes, atmospheric circulation, sea surface tempera-ture分类
天文与地球科学引用本文复制引用
王林,冯娟..我国冬季降水年际变化的主模态分析[J].大气科学,2011,35(6):1105-1116,12.基金项目
中国科学院知识创新工程重要方向项目KZCX2-EW-QN204,国家重点基础研究发展计划项目2009CB421405,国家自然科学基金资助项目41025017,国家海洋局海洋—大气化学与全球变化重点实验室开放基金GCMAC0901 （）
