Abstract
Studying the dynamic changes of extreme temperatures and associated large-scale atmospheric circulation is important for predicting the occurrence of extreme temperatures and reducing their adverse impact and damage. Based on the surface temperature data sets collected from 87 weather stations over the arid region of Northwest China (ARNC) during 1960–2017, the Sen’s slope estimator, Mann–Kendall test, Cumulative anomaly, Moving t-test, and Synthetic analysis methods were used to analyze the spatiotemporal dynamics and breaking-point change characteristics of extreme temperatures, and to discuss its associated large-scale atmospheric circulation. The results revealed that at the temporal scale, summer days (SU25), warm days (TX90p), warm nights (TN90p), and warm spell duration indicator (WSDI) showed a remarkable increasing trend at the rates of 2.27, 1.49, 3, and 2.28 days/decade, respectively. The frost days (FD), cold days (TX10p), cold nights (TN10p), and cold spell duration indicator (CSDI) significantly decreased at the rates of −3.71, −0.86, −1.77, and −0.76 days/decade, respectively, during the study period. Spatially, the warming trend in the study area is very obvious as a whole, despite pronounced spatial differences in warming rate. After the breakpoint years, the frequency and probability distribution for extreme warm and cold indices were all inclined to the hotter part of the density distribution. This indicates that the climate over the study region shifted sharply and tended to be warmer. The analysis of large-scale atmospheric circulation indicates that the warming trend in the arid region of Northwest China (ARNC) is positively correlated with geopotential height at 500 hPa and negatively correlated with total cloudiness. The findings from this study have important implications for forecasting extreme temperature events and mitigating the impacts of climatological disasters in this region.
Highlights
In recent decades, the frequent occurrence of extreme weather events such as heatwaves, cold surges, droughts, floods, and snowstorms has caused considerable casualties and immeasurable economic losses, which have received great attention worldwide [1,2,3,4]
Changes in extreme temperature affect the water cycle and hydrological process by changing the interaction and evaporation between the land and atmosphere, which in turn influences the spatial distribution of water resources. This means that better understanding the extreme temperature events is an important scientific issue in the field of climate change research, and an urgent requirement for the sustainable development of the natural ecosystem, society, and economy [22,23]
The temporal characteristics for temperature extremes indicate that the extreme warm indices are dominated by a significant increasing trend, while the extreme cold indices represent a pronounced decreasing trend over the study region during 1960–2017
Summary
The frequent occurrence of extreme weather events such as heatwaves, cold surges, droughts, floods, and snowstorms has caused considerable casualties and immeasurable economic losses, which have received great attention worldwide [1,2,3,4]. According to the estimation by the relevant departments of the United Nations, weather-related disasters account for 90% of the major disasters worldwide, and the number of people affected by extreme climate disasters in the world is 4.1 billion. This figure is seven times as many as those affected by wars and conflicts, resulting in property losses of about $100 billion every year globally, only in the 21 years from 1995 to 2015 [5]. This means that better understanding the extreme temperature events is an important scientific issue in the field of climate change research, and an urgent requirement for the sustainable development of the natural ecosystem, society, and economy [22,23]
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