Variations of Winter Precipitation over Southeastern China in Association with the North Atlantic Oscillation

作     者：Maoyuan LOU Chao LI Shifeng HAO Juan LIU Maoyuan LOU Chao LI Shifeng HAO and Juan LIU

作者机构：Zhejiang Provincial Meteorological Observatory Zhejiang Institute of Meteorological Sciences Zhejiang Meteorological Service Center 

出 版 物：《Journal of Meteorological Research》 (气象学报（英文版）)

年 卷 期：2017年第31卷第3期

页      面：476-489页

核心收录：

学科分类：07[理学] 0707[理学-海洋科学] 070601[理学-气象学] 0815[工学-水利工程] 0706[理学-大气科学] 0816[工学-测绘科学与技术] 0824[工学-船舶与海洋工程] 0825[工学-航空宇航科学与技术] 

基　　金：Supported by the National Natural Science Foundation of China(41405047 and 41675086) China Meteorological Administration Special Public Welfare Research Fund(GYHY201306010) 

主　　题：precipitation regime North Atlantic Oscillation (NA0) cluster analysis westerly jet stream 

摘      要：The synoptic-scale winter precipitation variations over southeastem China （22°-32°N, 105°-125°E） and their asso- ciation with the North Atlantic Oscillation （NAO） during 1951-2007 are investigated in this paper. The variability of wintertime precipitation is characterized by meridional displacement of its maximum center. Two precipitation re- gimes, with maximum centers located over the Yangtze and Pearl River basins, are identified via cluster analysis. Time-lagged analyses suggest that the two precipitation regimes are connected with the decaying phases of positive NAO （NAO＋） events of different amplitudes. A strong （medium） NAO＋ event is defined as one when the maximum amplitude of the NAO index exceeds 1.0 （in the range of 0.7-1.0） for at least 4 consecutive days and drops to less than 0.3 within 7 days following the peak index. After the peak of a strong NAO＋, southerly winds expand north- ward to the Yangtze River （about 30°N）, a northeast-southwest-tilted trough migrates to east of Lake Baikal, and cold air intrudes into central eastern China; thus, precipitation is strengthened over the Yangtze River basin where warm and cold air masses converge. In comparison, during the decaying phase of medium NAO＋ events, the south- erly winds are relatively weak, and precipitation tends to be enhanced at lower latitudes （around 25°N）. Further ana- lysis indicates that downstream Rossby-wave propagation may account for the latitudinal expansion of the southerly wind anomalies over the eastern coastal area of China during the decaying phase of NAO＋ events of different strengths.