Analysis Of Temperature And Snow Characteristics In Winter In Beijing And Zhangjiakou Region

Under the rising threat of globle warming,climate characteristics in Beijing and Zhangjiakou region is constantly changing,which has inpact on economic construction,social environment and agricultural production.Besides,Beijing and Zhangjiakou will undertake the 24th Olympic Winter Games,so it is necessary to study the variation trend and regulation of snow,winter temperature and extreme weather in this area,which can provide reference data and scientific basis for responses to climate change and disaster prevention and reduction.This paper reconstructed the snowfall amount during 1737?1960,analyzed the snow characteristics since 1937 and temperature characteristics since 1961 by using the Yu-Xue-Fen-Cun archives in Zhili province in the Qing Dynasty,monthly precipitation in Beijing during 1912?1960,daily precipitation and temperature of 8 stations in Beijing and Zhangjiakou area during 1960?2014;and identified extreme weather by using some indicators,the main conclusions are as follows:(1)Mean beginning snowfall date during 1737?1912 and 1961?2014 are November 19 and 24,ending snowfall date are March 16 and 15;mean snowfall days are 17.1 days and 15.8 days;snowfall days are less during 1760s?1770s,1860s?1880s and after 1990s,while snowfall days are more during 1810s?1840s and 1970s?1980s;mean snowfall amount in 278 years is 18.9mm,snowfall amount are more during 1737?1750s?1820s?1840s and 1980s?1990s,while it is less during 1760s?1770s and 1860?1890s;snowfall days and snowfall amount are more than the reconstructed value in fact beacause the observation in Qing Dynasty is rough.(2)Analysis of snow characteristics in each station during 1961?2014 shows:beginning snowfall date turned out to be delayed trend in each station except Yanqing,ending snowfall date show advanced trend in all stations;snowfall days shows decreasing trend except Chicheng and Guyuan;snowfall amount in Beijing shows decreasing trend;heavy snow happens more in Chongli,Guyuan,Zhangbei and Zhangjiakou;in each station,the dates over 60%probability included in maximum spells without precipitation are mostly occurred in late December?early January,and the spell is the longest in Zhangbei and shortest in Beijing.(3)Mean winter temperature in Beijing and Zhangjiakou area during 1961?2014 is-5.8?,minimum winter temperature is-11.5?;spells that daily mean temperature stably lower than 0 ??-5 ? and-10 ? and daily minimum temperature stably lower than 0 ??-5 ??-10? and-15? in each station are gradually shortend,and probability that the date included in the spells is the highest in January,the earlier or later the date is,the lower the probability is;spell that the probability over 60%is longer in Northern Zhangjiakou but shorter in Beijing;extreme low temperature in each station turned out to be increasing except Guyuan,and extreme low temperature is the lowest in late 1960s but higher in 1990s?2000s.(4)Snowfall days has significant correlation with daily mean temperature;,while ending snowfall date has significant correlation with daily minimum temperature.