Variations in the Drought Severity Index in Response to Climate Change on the Tibetan Plateau

Quantifying the relationship between the drought severity index and climate factors is crucial for predicting drought risk in situations characterized by climate change. However, variations in drought risk are not readily discernible under conditions of climate change, and this is particularly the case on the Tibetan Plateau. This study examines the correlations between the annual drought severity index (DSI) and 14 climate factors (including temperature, precipitation, humidity, wind speed, and hours of sunshine factors), on the Tibetan Plateau from 2000 to 2011. Spatial average DSI increased with precipitation and minimum relative humidity, while it decreased as the hours of sunshine increased. The correlation between DSI and climate factors varied with vegetation types. In alpine meadows, the correlation of the spatial DSI average with the percentage of sunshine and hours of sunshine (P<0.001) was higher compared to that in alpine steppes (P<0.05). Similarly, average vapor pressure and minimum relative humidity had significant positive effects on spatial DSI in alpine meadows, but had insignificant effects in alpine steppes. The magnitude of DSI change correlated negatively with temperature, precipitation, and vapor pressure, and positively with wind speed and sunshine. This demonstrates that the correlation between drought and climate change on the Tibetan Plateau is dependent on the type of ecosystem.