川渝地区夏季降水与赤道印度洋海温的诊断分析

利用川渝地区1960-2006年逐月降水量资料和美国NOAA Research/ESRL逐月再分析海表温度(SST)资料,采用经验正交函数分解(EOF)、点相关、合成分析和奇异值分解(SVD)等方法,详细探讨了川渝地区夏季降水量与赤道印度洋海温的关系。结果表明:川渝夏季降水量EOF分解得出的第一模态占总方差的27.8%,降水量的空间分布为全区一致型;川渝地区夏季降水量与赤道印度洋海温区域(10°N~16°S,57~77°E)(下称关键区)存在显著相关。合成分析指出关键区海温异常偏暖(冷),对应川渝地区夏季降水量比常年同期偏多(少)。通过SVD分解发现,川渝地区夏季降水量与关键区海温呈显著相关,具体表现为印度洋关键区海温与川西高原和盆地东部夏季降水量呈同位相变化,与盆地中部降水量呈反位相变化。

Diagnostic Analysis of the Relationships between the Summer Precipitation in the Sichuan-Chongqing Region and SST in the Equatorial Indian Ocean

Based on the precipitation data from 34 stations in Sichuan-Chongqing area and the monthly sea surface temperature (SST) reanalysis data of the NOAA/ESRL from 1960 to 2006, the relationship between the summer precipitation in the Sichuan-Chongqing region and SST of the Indian Ocean are studied by the methods of the empirical orthogonal function, point correlation, synthesis analysis and singular value decomposition analysis. The results of EOF for the summer standardized anomaly precipitation field shows that the first three modalities are steady and the first mode accounted for 27.8% of the total variance. The spatial distribution of precipitation presents the same type of the whole area. The analysis of point correlation shows that summer precipitation in the Sichuan-Chongqing region and the equatorial Indian Ocean region (10°N-16°S, 57-77°E) (hereinafter referred to as a key area) were significantly correlated. Synthetic analysis shows that when the SST of equatorial Indian Ocean anomalies was warmer (colder) than the normal, summer precipitation of the Sichuan-Chongqing region increased (decreased). SVD decomposition results show that summer precipitation in the Sichuan-Chongqing region and SST of the Indian Ocean was significantly correlated to the specific performance that SST of the Indian Ocean was in the same phase change with summer precipitation in eastern basin and western plateau of Sichuan Province, and the central basin was anti-phase change.