Changes of Extreme Temperature and Its Influencing Factors in Shiyang River Basin, Northwest China

Wei Wei,Wei Shi,Junju Zhou,Li Lei,Guofeng Zhu,Chunfang Liu,Lanying Wang,Xuemei Yang,Jumei Huang,Xi Zhao

doi:10.3390/atmos11111171

Abstract

The increase in the frequency and intensity of extreme weather events around the world has led to the frequent occurrence of global disasters, which have had serious impacts on the society, economic and ecological environment, especially fragile arid areas. Based on the daily maximum temperature and daily minimum temperature data of four meteorological stations in Shiyang River Basin (SRB) from 1960 to 2015, the spatio-temporal variation characteristics of extreme temperature indices were analyzed by means of univariate linear regression analysis, Mann–Kendall test and correlation analysis. The results showed that the extreme temperatures warming indices and the minimum of daily maximum temperature (TXn) and the minimum of daily minimum temperature (TNn) of cold indices showed an increasing trend from 1960 to 2016, especially since the 1990s, where the growth rate was fast and the response to global warming was sensitive. Except TXn and TNn, other cold indices showed a decreasing trend, especially Diurnal temperature (DTR) range, which decreased rapidly, indicating that the increasing speed of daily min-temperature were greater than of daily max-temperature in SRB. In space, the change tendency rate of the warm index basically showed an obvious altitude gradient effect that decreased with the altitude, which was consistent with Frost day (FD0) and Cool nights (TN10p) in the cold index, while Ice days (ID0) and Cool days (TX10p) are opposite. The mutation of the cold indices occurred earlier than the warm indices, illustrating that the cold indices in SRB were more sensitive to global warming. The change in extreme temperatures that would have a significant impact on the vegetation and glacier permafrost in the basin was the result of the combined function of different atmospheric circulation systems, which included the Arctic polar vortex, Western Pacific subtropical high and Qinghai-tibet Plateau circulation.

Highlights

The Fifth Assessment Report of IPCC indicated that the surface temperature showed a change tendency rate of increase from 1880 to 2012, with an increase of 0.85 ◦ C
The interannual tendency rate of each extreme temperatures index was calculated by using the method of one-dimensional linear regression analysis, and its significance was tested (Table 3)
The results show that Arctic Oscillation (AO) and Northern Hemisphere Polar Vortex Area Index (NHPVAI)

Summary

Introduction

The Fifth Assessment Report of IPCC indicated that the surface temperature showed a change tendency rate of increase from 1880 to 2012, with an increase of 0.85 ◦ C. Global warming has led to increased frequency of extreme climate events [3,4]. The highest trend of the lowest temperature indices, the increase in the extreme temperatures indices and the decrease in the cold extreme value all show the obvious warming trend from the 20th century to the beginning of the 21st century [3,10]. In most extreme temperatures indices in Asia, the variation range in a high latitude is larger than that in a low latitude [3,12], the number of warm days and nights is increasing, and the increasing speed of the latter is significantly higher than that of the former [13]. In the past 30 years, the extreme temperatures values in Central Asia and North America have shown an increasing trend year by year, but the growth rate of the highest temperature (TMAX) is faster than that of the lowest temperature (TMIN), resulting in the overall increase in the diurnal temperature range (DTR) [14,15]

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Results

Discussion

Conclusion