Abstract
Temperature and precipitation extremes are the dominant causes of natural disasters. In this study, seven indices of extreme temperature and precipitation events in Gansu Province, China, were analysed for the period 1961–2017. An abrupt climate shift was recorded during 1980–1981. Thus, the study period was divided into a preshift (before the climate shift) period 1961–1980 and an aftshift (after the climate shift) period 1981–2017. Comparison of mean extreme indices for preshift and aftshift periods was performed for the purpose of exploring possible increasing/decreasing patterns. Generalized extreme value (GEV) distribution was applied spatially to fit the extreme indices with return periods up to 100 years for preshift/aftshift periods. Singular value decomposition (SVD) was adopted to investigate possible correlation between the extreme climate events and indices of large-scale atmospheric circulation. The results indicate that changes in mean and return levels between the preshift and aftshift periods vary significantly in time and space for different extreme indices. Increase in extreme temperature regarding magnitude and frequency for the aftshift period as compared with the preshift period suggests a change to a warmer and more extreme climate during recent years. Changes in precipitation extremes were different in southern and northern parts of Gansu. The precipitation extremes in the north have increased that can result in more serious floods and droughts in the future. SVD analyses revealed a complex pattern of correlation between climate extremes and indices of large-scale atmospheric circulation. Strengthening of westerlies and weakening of the south summer monsoon contribute to the complex changing patterns of precipitation extremes. Results in this study will contribute to disaster risk prevention and better water management in this area.
Highlights
Extreme climate events are of great concern for the public, government and the academic community due to their disastrous environmental and socio-economic consequences
To describe modes of atmospheric circulation, this study considered four climate indices influencing climate variability over China and especially northern China: North Atlantic Oscillation (NAO), Southern Oscillation Index (SOI), East Atlantic/West Russia Pattern (EA/WR) and Pacific Decadal Oscillation (PDO)
Seven temperature and precipitation extreme indices were analysed related to the period 1961–2017 and using data from 27 meteorological stations in Gansu Province, China
Summary
Extreme climate events are of great concern for the public, government and the academic community due to their disastrous environmental and socio-economic consequences. The occurrence of extreme events and their potentially severe impacts have been emphasized due to climate change effects Northwestern China is one of the most arid areas in East Asia. Many studies have shown that Northwestern China is more sensitive to extreme climate events as compared with other areas. It has been found that temperature and precipitation in Northwestern China have experienced a sharp increase during the past 50 years (Chen et al 2015). The results indicate a severe future climate situation in Northwestern China with larger variability for both temperature and precipitation
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