Abstract
Drought is one of the most severe natural disasters. However, many of its characteristic variables have complex nonlinear relationships. Therefore, it is difficult to construct effective drought assessment models. In this study, we analyzed regional drought characteristics in China to identify their relationship with changes in meridional and zonal temperature gradients. Drought duration and severity were extracted according to standardized precipitation evapotranspiration index (SPEI) drought grades. Trends in drought duration and severity were detected by the Mann-Kendall test for the period of 1979–2019; they showed that both parameters had been steadily increasing during that time. Nevertheless, the increasing trend in drought severity was particularly significant for northwest and southwest China. A composite analysis confirmed the relationships between drought characteristics and temperature gradients. The northwest areas were relatively less affected by temperature gradients, as they are landlocked, remote from the ocean, and only slightly influenced by the land–ocean thermal contrast (LOC) and the meridional temperature gradient (MTG). The impacts of LOC and MTG on drought duration and severity were positive in the southwest region of China but negative in the northeast. As there was a strong correlation between drought duration and severity, we constructed a 2D copula function model of these parameters. The Gaussian, HuslerReiss, and Frank copula functions were the most appropriate distributions for the northeast, northwest, and southwest regions, respectively. As drought processes are highly complex, the present study explored the internal connections between drought duration and severity and their responses to meteorological conditions. In this manner, an accurate method of predicting future drought events was developed.
Highlights
Drought has devastating impacts and may be complex, variable, and highly destructive to human-environment systems
What are the connections between the temperature gradient patterns and regional between the drought characteristics and the temperature gradients in China? and (3) What drought in China? The present study proposed copula-based drought monitoring are the connections between the temperature gradient patterns and regional drought in and assessment approaches that help clarify the potential impact of climate systems on
The present study focused on the links between the east–west and north–south temperature gradients in the northern hemisphere and the regional droughts in China
Summary
Drought has devastating impacts and may be complex, variable, and highly destructive to human-environment systems. Drought occurs in most global climate regions, but it differs in each region [1,2]. It has a significant effect on water resources [3], agricultural production [4], economic activity [5], and ecosystems [6,7]. Europe has been affected by numerous major drought events over the past 30 years, especially in 1976, 1989, 1991, and 2003 [11]. Extreme droughts occurred in the late 1990s in many parts of China. Persistent, severe, multiyear droughts have frequently occurred in northern, northeastern, northwestern, and southwestern China [12]. The Fifth IPCC Assessment Report stated that the global surface temperature rose by 0.85 ◦ C (0.65–1.06 ◦ C)
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