Abstract
The frequent occurrence of drought events in humid and semi-humid regions is closely related to the global climate variability (GCV). In this study, the Standard Precipitation Evapotranspiration Index (SPEI) was taken as an index to investigate the drought in the Yangtze River Basin (YRB), a typical humid and semi-humid region in China. Furthermore, nine GCV indices, such as North Atlantic Oscillation (NAO) were taken to characterize the GCV. Correlation analysis and a joint probability distribution model were used to explore the relationship between the drought events and the GCV. The results demonstrated that there were six significant spatiotemporal modes revealed by SPEI3 (i.e., seasonal drought), which were consistent with the distribution of the main sub basins in the YRB, indicating a heterogeneity of drought regime. However, the SPEI12 (i.e., annual drought) can only reveal five modes. Precipitation Indices and El Niño/Southern Oscillation (ENSO) Indices were more closely related to the drought events. A causal relationship existed between ENSO precipitation index (ESPI), NAO, East Central Tropical Pacific Sea Surface Temperature (Nino3.4) and Northern Oscillation Index (NOI) and drought in the YRB, respectively. Drought events were most sensitive to the low NAO and high NOI events. This study shows a great significance for the understanding of spatiotemporal characteristics of meteorological drought and will provide a reference for the further formulation of water resources policy and the prevention of drought disasters.
Highlights
Drought is a serious natural disaster all over the world
The drought we mentioned in the humid and semi-humid regions generally refers to a drought event or a seasonal water shortage, which is different from the drought in the arid region like north-west China
The margin distributions of these five indices were detected and the results indicated that Standardized Precipitation Evapotranspiration Index (SPEI), ENSO precipitation index (ESPI), North Atlantic Oscillation (NAO), Nino3.4, and Northern Oscillation Index (NOI) all followed the logistic distribution
Summary
Drought is a serious natural disaster all over the world. It is often considered to be one of the well-known natural disasters [1,2,3,4]. The effects of drought are often magnified especially in the context of global climate change [5,6,7,8]. Drought can be divided into four types: Meteorological drought, Agricultural drought, Hydrological drought and Social-economic drought [9]. Meteorological drought is a prerequisite for the other three droughts. Droughts occur over most parts of the world, both in arid and humid regions [10]. Understanding the spatiotemporal variations of drought is of primary importance for freshwater planning and management [11]
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