Changes in Annual and Seasonal Temperature Extremes in the Arid Region of China

In recent years, there is an increasing concern in weather and climate extremes, since they may cause serious disasters to human society and nature and seem to be more sensitive to climate change than mean values. Many results have shown that the increases in economic losses, coupled with a rise in deaths, may be caused due to the facts that climate extremes are increasing in frequency and intensity. Furthermore, changes in extremes can be strong indicators of climate change. Exploring changing characteristics of extreme temperature in the arid region of China is a prerequisite for the assessment of impacts of climatic changes on regional ecological environment and agricultural development.

Therefore, WANG Huaijun et al. use the daily data of minimum and maximum temperature from 76 meteorological stations for 1960–2010 to detect the annual and seasonal variations of temperature extremes in the arid region, China. The Mann–Kendall test and Sen estimator are used to assess the significance of the trend and amount of change, respectively.

The temperature extremes show patterns consistent with warming, with a large proportion of stations showing statistically significant trends. Warming trends in indices derived from daily minimum temperature are of greater magnitudes than those from maximum temperature, and stations along the Tianshan Mountains have larger trend magnitudes. The decreases in frequency for cold extremes mainly occur in summer and autumn, while warm extremes show significant increases in frequency in autumn and winter.

For the arid region as a whole, the occurrence of cold nights and cold days has decreased by –1.89 and –0.89 days/decade, respectively, and warm nights and warm days has increased by 2.85 and 1.37 days/decade, respectively. The number of frost days and ice days exhibit significant decreasing trends at the rates of –3.84 and –2.07 days/decade. The threshold indices also show statistically significant increasing trends, with the extreme lowest temperatures faster than highest temperatures. The diurnal temperature range has decreased by 0.23 ºC/decade, which is in accordance with the more rapid increases in minimum temperature than in maximum temperature.

The results of this study will be useful for local human mitigation to alterations in water resources and ecological environment in the arid region of China due to the changes of temperature extremes. The result was published in Natural Hazards in February 2013, 65(3): 1913-1930.