| Popis: |
【Objective】 The purpose of this paper is to analyze the spatial and temporal distribution pattern of drought in the three northeastern provinces from 1961 to 2020. 【Method】 Based on the measured data of 86 meteorological stations in the three provinces of Northeast China from 1961 to 2020, the standardized precipitation evapotranspiration index (SPEI) at different time scales over the past 60 years was calculated, and the spatiotemporal variation characteristics of drought in the three northeastern provinces by using run theory, Mann Kendall test, empirical Orthogonal functions (EOF) decomposition and other methods were analyzed. 【Result】 On an annual scale, SPEI all tended to decrease slowly, but they were overall above -2.0 with no significant mutation points. The frequency of drought occurrence was 25.5%-37.6%. The frequency of moderate, severe and extreme droughts showed a distribution pattern of ‘high-low-high’, ‘high in the middle and low on both sides’, and ‘gradually decreasing’ from west to east; On seasonal scale, there was a downward trend in spring, summer and autumn, while an upward trend in winter. This indicated that the drought in the three northeastern provinces has been alleviated in winter, while the drought in spring, summer and autumn has intensified. The frequency of drought occurrence in space was spring>winter>summer>autumn; The longer the duration of drought was, the lower the intensity of drought was, which indicated that the site was drier; The main spatial modes of the first four eigenvectors obtained from EOF decomposition at the interannual scale and the first eigenvector obtained from seasonal scale decomposition were consistent across the entire region, with north-south reverse distribution characteristics. 【Conclusion】 In the three northeastern provinces, except for spring and winter, the annual and the remaining two seasons of SPEI showed a decreasing trend, with an increasing trend of drought in the south and a wetting trend in the north. |
