Responses of agricultural drought to meteorological drought under different climatic zones and vegetation types

Meteorological drought (MD) is strongly causal linked to agricultural drought (AD), therefore, MD can be used as an appropriate early warning of AD, enhancing human mitigation of AD. However, drought responses of AD to MD have not been well understood. Here we used the nonstationary standardized precipitation evapotranspiration index (NSPEI) and the standardized soil moisture index (SSI) to analyze the evolution characteristics of MD and AD. The drought response time (DRT) and response patterns of drought in different climatic zones with different underlying surface conditions (vegetation type, irrigation) were calculated. A high frequency of MD and AD in southeastern China and the Tibetan Plateau was detected. Besides, AD in southeastern China and MD in central and southern China showed a significant increasing trend. Meanwhile, MD and AD are in the same decreasing trend over the Tibetan Plateau. The highest probability of compound droughts can be found in northern China and regions with a semi-humid warm temperate climate. Drought response sensitivity is higher with shorter agriculture drought response time (DRT) in southeastern China and eastern parts of the Tibetan Plateau than in other regions of China. Besides, DRT is short in summer and autumn, and long in winter and spring. Moreover, when compared to DRT in irrigated agricultural areas, DRT in rainfed agricultural areas is longer and more spatially variable. DRT in double- and triple-crop irrigated areas is remarkably shorter than in single-crop irrigated areas, and DRT with higher crop intensity is shorter.