Drought stress and its characteristics in China from 2001 to 2020 considering vegetation response and drought creep effect

China Drought is an extremely serious disaster, typically characterized by slow onset, long duration, and cumulative impacts on multifaceted aspects. Developing a combined index that integrates its various characteristics can help deepen our understanding of drought evolution and provide accurate references for farmers to take drought mitigation measures. In this study, we proposed a Modified version of the Type Response-Aided Drought Index (MTRADI), simultaneously considering the various responses of different vegetation and the slow-varying properties of drought development. The suitability of MTRADI was evaluated through correlation analysis with Palmer Drought Severity Index (PDSI) and qualitative comparison with Meteorological Drought Composite Index (MCI) maps. The MTRADI achieved significantly higher correlation coefficients with the PDSI, outperforming other combined drought indices. Based on the run theory, Mann-Kendall (MK) test, and Sen's slope, drought characteristics and trends in mainland China during 2001–2020 were analyzed and the results show that drought frequency and severity are relatively higher in eastern Inner Mongolia, North China Plain, and Northeast of China. Furthermore, areas with significant wetting trends are observed to be mainly distributed near the Hu line, indicating that the water conditions in China are gradually improving at the transition zone of arid and humid climate regions.