Spatiotemporal Variation of Precipitation in the Fergana Basin from 1950 to 2019 and Its Impact Mechanism
Based on the Fergana Basin precipitation grid data from 1950 to 2019,linear regression and empirical orthogonal function(EOF)analysis were used to explore the spatiotemporal distribution of interannual precipitation in the Fergana Basin,and to study the factors affecting large-scale circulation.The results indicate that:(1)The precipitation shows a decreasing trend with-2.2 mm/10 a in the Fergana Basin from 1950 to 2019,and did not pass the significance test,and none of the tests on precipitation in individual months reveals a significant trend.(2)There are two main modes of precipitation in Fergana Basin,which explain 70.52%of the precipitation change in the whole region,and the first mode can explain 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.The El Niño/Southern Oscillation(ENSO)event affects the precipitation changes in the Fergana Basin 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 Fergana Basin.
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