Assessing Spatiotemporal Characteristics of Drought based on SPI in Mongolia Plateau

This study is based on the SPI that was calculated from precipitation data of the TerraClimate dataset during 1958-2017, analysis of spatiotemporal characteristics of drought in Mongolia Plateau using climate trend and Pettit mutation method, the results showed that the Mongolian Plateau get significant drier trend with a rate of 0.155/decade. In spring and autumn, the trend of humidification was observed, while in summer and autumn, the trend of aridity was observed. In the summer, the SPI value showed a significant decrease with a rate of 0.2075/ decade; The pixel-by-pixel analysis of the SPI trend found that the proportions of the drought-reduced trends in spring, summer, autumn and winter were 18.47%, 95.22%, 53.49%, and 4.28%, respectively. It showed a significant aridity insummer, the annual arid area of the Mongolian Plateau accounted for 90.06%; the summer SPI changed more drastically, accounting for 29.39% of the area. It is mainly located in the central and northern regions of the study area, while the change of SPI in winter is mainly located in the northeast region, accounting for 19.04%.