气候变暖对中国亚热带北界位置的影响

Impact of climate warming on the northern boundary of sub-tropical zone of China

在全球气候变暖的背景下,中国气候带也有相应的变化。亚热带北界是暖温带与北亚热带的交界,是中国气候带上的一个重要分界线。论文讨论了气候变暖对中国亚热带北界的影响。数据资料来自于中国气象局,采用中国740个站点1951-2005年的日平均温度资料。根据《中华人民共和国气候图集》中气候区划的第一级气候带定义指标,以≥10℃天数为主导指标,≥10℃积温、1月平均温度为辅助指标,定义亚热带北界为≥10℃天数为218天,≥10℃积温为4500-4800℃,1月平均气温为0℃。分别统计1951-2005年暖温带与亚热带指标的年代变化及亚热带北界在1951-1970、1971-1990、1991-2005年的位置演变,结果表明：34°N附近55年来≥10℃天数、≥10℃积温、1月平均温度都呈上升趋势。20世纪50年代至今,亚热带北界西段几乎没有变化;亚热带北界中东段向北推移幅度较大,到本世纪初向北已推移到35°N附近,较1951-1970年向北推移2-3个纬度。亚热带北界位置的向北推移是对全球气候变暖的一种响应,这将对我国农业布局和生态环境有重要影响。

Changes of the climatic zones are related to climate warming and its impacts. The northern boundary of sub-tropical zone is between the temperate and sub-tropical zones, which is a very important boundary in China＇s climatic divisions. In this paper a case study is made on the impact of climate warming on the northern boundary of sub-tropical zones of China. The data covering about 55 years （1951-2005） of daily mean temperature with 740 stations are obtained from China Meteorological Administration. According to the definition of the first class climatic zone from Climatological Atlas of the People＇s Republic of China, the authors use the number of days with secular pentad mean temperature passing through ≥10℃as the main index, and January mean air temperature as the auxiliary indices. Namely the definition of the northern boundary of sub-tropical zone is the divide where the number of days with secular pentad mean temperature passing through ≥10℃ reaches 218, the accumulated temperature with ≥10℃ is 4500 -4800℃, and January mean air temperature is 0℃ The authors count respectively the inter-decadal changes of indices of the first class climatic zone in north sub-tropical and temperate zones in 1951- 2005, and the changes of the north sub-tropical belt in the periods 1951- 1970, 1971-1990 and 1991-2005. The results show that： the number of days of secular pentad mean temperature passing through ≥10℃, the accumulated temperature ≥10℃ and January mean air temperature all have an upward trend in the 55 years in the vicinity of 34 degrees north latitude. Since the 1950s, there has been little change in the western section of the northern boundary of sub-tropical zone; the central and eastern sections of the northern boundary of sub-tropical zone moved to the north over a large range. By the beginning of the 21st century the central and eastern sections has moved to near 35°N, i. e. , 2-3 degrees of latitude northward, compared with the period 1951-1970. The northern boundary of sub-tropical zone moving towards the north, which is a response to climate warming, will have a very important influence on the agricultural pattern and the ecological environment.