山西省夏季降水与赤道东太平洋海温关系初探

Relationship Between Summer Precipitation of Shanxi Province and SST in Eastern Equatorial Pacific

利用山西省58个台站1960-2009年有观测记录的50 a夏季降水资料和NCEP/NCAR逐月再分析位势高度场、NOAA逐月海温场资料,研究了山西省旱、涝年大气环流特征差异,并进一步讨论了山西省夏季降水异常与赤道东太平洋(Nino区)海温异常的关系。研究结果表明:山西省夏季降水异常年从前期春季到同期夏季,欧亚中高纬度500 hPa位势高度的大气环流存在异常,尤其是乌拉尔山高压脊、贝加尔湖低槽及西太平洋副热带高压等大尺度环流系统都有明显的变化;850 hPa风场上蒙古气旋南部纬向风的异常,以及我国东部到华北地区经向风(东亚夏季风)的异常,是直接影响山西省夏季降水的重要环流因子;赤道东太平洋秘鲁冷水舌和太平洋东岸暖水舌均是山西省夏季降水的敏感区,Nino区域前期海温异常对山西省夏季降水有显著的影响,即Nino区域前期海温偏低有利于山西省夏季降水偏多。

Based on NCEP/NCAR monthly reanalysis geo-potential height,NOAA monthly SST data and the 50 a （1960-2009） rainfall over 58 meteorological stations in Shanxi province, the unusual characteristics of general circulation in drought and flood years of Shanxi are investigated, and the correlationbetween the summer precipitation index of Shanxi province and the SST field in eastern equatorial Pacific is further studied. Results show that in the years of the summer precipitation anomalies of Shanxi, the large-scale circulation systems of 500 hPa geo-potential height are obviously different, such as a high- pressure ridge over the Ural Mountain and deep trough over Baikal Lake and West Pacific subtropicalhigh. The zonal wind of 850 hPa in the southern of Mongolian cyclone and Meridional wind （East Asian summer monsoon） over eastern regions of China to North China tend to exhibit anomalies, which have great impact on the summer rainfall of Shanxi province. The cold SST tongue from eastern equatorial Pa- cific SST and the warm SST tongue from the East Pacific coast often effect a change of circulation sys- tems, which has a significant impact on summer precipitation of Shanxi. Nino region SST anomalies has a significant impact on the summer precipitation of Shanxi province, that is, the lower sea surface tempera- ture of Nino region is conducive to summer more rainfall of Shanxi province.