利用1961-2008年陕西78个气象站夏季(6-8月)降水资料、NOAA提供的全球逐月海表温度资料和NCEP/NCAR 500 h Pa位势高度场、风场月平均再分析资料,运用回归、SVD、交叉小波分析等方法分析了前期到同期不同季节太平洋、印度洋海温与陕西夏季降水的关系。结果表明,陕西夏季降水与前期秋、冬季节赤道中东太平洋、西印度洋海温呈正相关关系,与北太平洋海温呈负相关关系,太平洋海温分布为El Nino型;到同年夏季,显著正相关区西移到东印度洋和我国东部沿海,前期及同期太平洋、印度洋海温影响陕西的显著区域都位于关中和陕南东部。冬季Nino3海温与陕西夏季降水在4~5年时间尺度有显著的同位相共振周期,Nino3海温超前陕西夏季降水变化4~6个月。东亚、南海、东南亚夏季风指数与陕西夏季降水呈负相关关系,与Nino3海温也呈负相关关系,当前期Nino3海温偏高时,东亚夏季风减弱,西太平洋副热带高压偏强、偏西,陕西南部有异常西南风水汽输送,北部有异常北风,陕西处于冷暖空气的交汇区,夏季降水偏多,反之偏少。
Based on the reanalysis data of monthly mean global SST and wind from the NCEP/NCAR and the observation data of rain seasons in 124 stations of Yunnan province from 1961 to 2006, we applied the analytical methods of correlation analysis and composite analysis and a significance testing method to two sets of samples of average differences. The goal is to investigate into the influence of the Southern Hemispheric(SH) SST on the summer precipitation in Yunnan from January to May so as to identify the key time and marine regions. Physical mechanisms are obtained by analyzing the influence of sea level wind and the key marine regions on the precipitation during Yunnan's rain season.Results show that there is indeed significant relationship between the SST in SH and summer precipitation in Yunnan.The key areas for influencing the summer precipitation are mainly distributed in a region called "West Wind Drift" in the SH, including the Southeast Indian, southern Australia, west coast of eastern Pacific off Chile, Peru and the southwest Atlantic Magellan. Besides, the most significant marine region is the west coast of Chile and Peru(cold-current areas of the eastern Pacific). Diagnostic analysis results also showed that monsoons in the Bay of Bengal, a cross-equatorial flow in the Indian Ocean near the equator and southwest monsoon in India weaken during the warm phase of the Peruvian cold current in the eastern Pacific. Otherwise, they strengthen.
