Study on Temporal-spatial Change Characteristics of the Extremely Low Temperature Climate Event in Winter of China.

[Objective] The research aimed to study temporal-spatial change characteristics of the extremely low temperature climate event in winter of China. [Method] By using actual probability distribution threshold value method, EOF analysis method and the daily minimum temperature data in winter of 1961-2008 at 195 observatories of China, temporal-spatial change characteristics of the extremely low temperature climate event in winter of China in 48 years were analyzed. [Result] Threshold value calculated by actual probability distribution was higher than that by traditional method, and increase magnitude in east was bigger than that in west, which could describe climatic change situation in China in 48 years better than traditional method. Cold night number in winter of China did not decrease as latitude declined, and it was more in south and north and was less in Yellow River basin and northwest China. Cold night number was the most in northeast Inner Mongolia. Interannual change of the cold night number presented decline tendency. From the 1960s to the early 1970s, cold night number consistently increased, and change in middle and late periods of the 1960s was severe. From the early 1970s to the middle 1980s, fluctuation of the cold night number was bigger, and increase of the cold night number was the most in 1976. Cold night number from 1986 to the 21st century continuously declined. Change of the cold night number was the most obvious in east region, Guizhou and north Guangxi. Cold night number in northeast China and north Inner Mongolia presented inverting change relationship with that in Yunnan-Kweichow Plateau and Hexi Corridor. [Conclusion] The research provided reference for early warning of the extremely low temperature event in China. [ABSTRACT FROM AUTHOR]