Abstract
The occurrence of droughts has become more frequent, and their intensity has increased in mainland China. With the aim of better understanding the influence of climate background on drought events in this region, we analyzed the role of the drought-related factors and extreme climate in the formation of droughts by investigating the relationship between the drought severity index (denoted as GRACE-DSI) based on the terrestrial water storage changes (TWSCs) derived from Gravity Recovery and Climate Experiment (GRACE) time-variable gravity fields and drought-related factors/extreme climate. The results show that GRACE-DSI was consistent with the self-calibrating Palmer Drought Severity Index in mainland China, especially for the subtropical monsoon climate, with a correlation of 0.72. Precipitation (PPT) and evapotranspiration (ET) are the main factors causing drought events. However, they play different roles under different climate settings. The regions under temperate monsoon climate and subtropical monsoon climate were more impacted by PPT, while ET played a leading role in the regions under temperate continental climate and plateau mountain climate. Moreover, El Niño–Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) events mainly caused abnormalities in PPT and ET by affecting the strength of monsoons (East Asian and Indian monsoon) and regional highs (Subtropical High, Siberian High, Central Asian High, etc.). As a result, the various affected regions were prone to droughts during ENSO or NAO events, which disturbed the normal operation of atmospheric circulation in different ways. The results of this study are valuable in the efforts to understand the formation mechanism of drought events in mainland China.
Highlights
The values of Gravity Recovery and Climate Experiment (GRACE)-DSI were mostly negative during the second period from June 2006 to February 2010, coinciding with Self-Calibrating Palmer Drought Severity Index (SCPDSI)
To discuss the cause of drought events under different climatic conditions, we took four climatic regions in Mainland China (MC) as an example to study the influences of various hydrological components and extreme climate on drought events using GRACE-DSI data
This proves that GRACE-DSI can detect drought events in MC
Summary
Drought is a severe natural hazard event on a global scale characterized by terrestrial water deficit. The commonly used drought indices are mainly the palmer drought severity index (PDSI) [6], the standardized precipitation index (SPI) [7] and the standardized runoff index (SRI) [8]. These traditional drought indices are mainly calculated based on the long-term accumulation of drought-related data such as precipitation (PPT), evapotranspiration (ET), temperature, etc. It is impossible to explain the cause of drought from the perspective of the entire terrestrial water cycle
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