天水地区降水时空特征及其对印度洋偶极子的响应

Spatiotemporal Pattern of Precipitation in Tianshui Region and Its Response to the Indian Ocean Dipole

采用Mann—Kendall及自然正交分解（EOF）方法，对渭河流域上游天水地区18个降水观测站1956—2005年系列资料进行趋势检验与距平场的EOF分析。结果表明：该区域的降水自1994年以来有明显减少趋势，并存在全部一致型、东西型和南北型3种典型的降水类型。其中，第一特征向量的方差贡献率占82．2％，全部一致型的降水分布类型在该区域为主导。同时，该区域降水与印度洋偶极子有较好的正、负相关性？其中，正相关的延时为7～8个月，负相关的延时为2～3个月：

Based on the precipitation data from meteorological stations in Tianshui region located in the upper reaches of the Weihe River, the trend characteristics of precipitation change in resent 50 years are ananlyzed by using Mann-Kendall method and Empirical Orthogonal Function in precipitation in the study area has been occurring since （EOF） analysis . The results show that a decrease trend 1994. The results also reveal that there are three precipitation patterns in the study area, i.e. the all-consistency pattern, north-south pattern and west-east pattern. The first eigenvector is dominant in the study area, and its accumulation contribution rate is 82.2%. Moreover, there is a high correlation between the precipitation trend and the Indian Ocean DIPOLE. The delay time of positive correlation is for 7 - 8 months and of negative one for 2 - 3 months.