费尔干纳盆地1950-2019年降水时空变化及其影响机制

基于1950-2019年费尔干纳盆地降水格点数据，利用线性回归法和经验正交函数（EOF）分析等方法，探究了费尔干纳盆地降水年际变化的影响因素及其空间分布模态，并研究了降水时空变化后的大尺度环流影响因素。结果显示：（1）1950-2019年，费尔干纳盆地降水总体呈下降趋势，为-2.20mm/10a，但并未通过显著性检验，同时对单个月份的降水进行检验也都未发现明显趋势。（2）费尔干纳盆地降水的主要模态有两个，解释了全区降水变化的70.52%，第一模态解释了全区降水变化的59.90%，空间向量场呈现全区一致型，表征研究区整体的降水变化情况，受到ENSO和西风带的影响；第二模态解释了全区降水变化的10.62%，空间向量场表现出从西北到东南的空间反相模态，表征研究区降水空间异质性，受到欧亚大陆北部输送的水汽影响。（3）厄尔尼诺/南方涛动（ENSO）事件通过调整水汽输送路径和季风环流模式影响了费尔干纳盆地的降水变化；来自欧亚大陆北部的气流是造成费尔干纳盆地降水空间格局差异的主要原因。

The spatiotemporal variation of precipitation in the Fergana Valley from 1950 to 2019 and its impact mechanism

Based on the Ferghana Valley precipitation grid data from 1950-2019, the factors influencing the interannual variability of precipitation in the Ferghana Valley and its spatial distribution modes were investigated using methods such as linear regression method and empirical orthogonal function (EOF) analysis, and the large-scale circulation influences following spatial and temporal variability of precipitation were also investigated. The results indicate that (1) the overall decreasing trend of precipitation in the Ferghana Valley from 1950 to 2019 is -2.2mm/10a, but it does not pass the significance test, while none of the tests on precipitation in individual months reveals a significant trend. (2) There are two main modes of precipitation in Fergana Valley, which explain 70.52% of the precipitation change in the whole region, and the first mode explains 59.90% of the precipitation change in the whole region. The spatial vector field presents a consistent pattern in the whole region, representing the overall precipitation change in the study area, affected by ENSO and westerlies; The second mode explains 10.62% of the precipitation change in the whole region, and the spatial vector field shows the spatial inverse mode from northwest to southeast, representing the spatial heterogeneity of precipitation in the study area, which is affected by the water vapor transported from the northern Eurasia. (3) The El Ni?o/Southern Oscillation (ENSO) event affects the precipitation changes in the Ferghana Valley by adjusting the water vapor transport paths and the monsoon circulation pattern; the airflow from the northern part of the Eurasian continent is the main reason for the differences in spatial patterns of precipitation in the Ferghana Valley.