基于有效干旱指数的锡林郭勒干旱时空分布特征.

[Objective] The aims of this study are to identify drought events, drought frequency and drought intensity in grassland of Xilin Gol, to understand the meteorological drought field in Xilin Gol, and then to alleviate the environmental and economic problems caused by drought in Xilin Gol. [Methods] The month-by-month observation data of nine meteorological stations in Xilin Gol region from 1969 to 2018 were selected to calculate the effective drought index (EDI) . The spatial and temporal patterns of drought in Xilin Gol over the past 60 years were analyzed by combining Mann-Kendall test, empirical orthogonal function (EOF) decomposition and quantitative drought characterization methods. [Results] The annual average EDI index of Xilin Gol region decreased at the rate of 0.029/decade, and the drought trend increased significantly, with an average of 0.5 drought events per year. The frequency of normal occurrences in Xilin Gol ranged from 67.17 to 72.65%, and the frequency of severe droughts ranged from 0.02 to 0.99%, with a large variability in the frequency of different droughts, and the southwest and central regions being the regions with higher drought intensity. Contribution of variances of the previous two major characteristic vectors of Xilin Gol reached up to 52.75% and 14.38%, respectively, and the spatial mode showed a consistent type and southeast-northwest inversion phase type. [Conclusion] EDI index considering effective precipitation has more advantages in revealing the spatiotemporal variation trend of drought in grassland, and can be used to identify the spatiotemporal variation of meteorological drought. [ABSTRACT FROM AUTHOR]