南印度洋偶极子与我国夏季降水的联系

The Connection of the Southern Indian Ocean Dipole and Summer Precipitation in China

摘要: 利用NCEP/NCAR再分析资料、Hadley海温资料以及CRU TS v4.03降水资料，通过EOF分解、相关分析和合成分析等方法分析了冬、春季南印度洋偶极子(Southern Indian Ocean Dipole, SIOD)特征及其与我国夏季降水的联系。结果表明：1) 南印度洋冬、春季海温具有明显的偶极子特征，且SIOD在12月~次年5月存在强弱和相位变化。2) SIOD指数与中国夏季逐月降水相关性在6、7、8月分别呈西正东负，北负南正和我国东、西部为正、中部较弱的分布特征；不同月份关键区降水的时间序列特征进一步表明春季SIOD指数与我国夏季降水联系密切。3) 春季SIOD可通过风场和水汽输送异常影响夏季逐月降水，其中6月主要通过南印度洋和太平洋水汽影响我国南方降水，而7月主要影响太平洋水汽输送，8月则主要影响由云南进入我国内陆的南印度洋东北部的水汽输送。

Abstract: This paper uses NCEP/NCAR reanalysis data, Hadley sea surface temperature data and precipitation data of CRU TS v4.03 to study the characteristics of Southern Indian Ocean Dipole and its connection with summer precipitation over China by empirical orthogonal function decomposition, correlation analysis and synthetic analysis. The results show that: 1) The winter and spring sea temperature had obvious dipole characteristics, and SIOD had strength and phase changes from December to May. 2) The distribution characteristics of correlation between SIOD index and monthly precipitation were positive in west (north) and negative in east (south) China in June (July), and positive in east and western China and negative in middle China. The time series of precipitation in key areas in different months further show that the spring SIOD index is closely related to the summer precipitation over China. 3) Spring SIOD can affect the abnormal monthly precipitation through wind field and water vapor transport in summer; the precipitation in southern China was mainly affected through the water vapor of the southern Indian Ocean and Pacific Ocean in June, precipitation over China mainly affected by water vapor delivery in the Pacific in July, but mainly affected by water vapor in the northeast of the southern Indian Ocean in August, which entered into inland China through Yunnan.