关键词: 西北西风带, 冬季气温, 气候变暖

Abstract: The mean surface air temperature data over the years 1961—2006 of 193 stations within China northwestern arid and semi-arid area (CNASA) were used to analyze the response of the annual mean air temperature to global warming by methods of linear regression analysis, multinomial fitting, EOF, REOF, Mann-Kendall, Glide T-examination, wavelet analysis and power spectrum analysis etc. The results show that: ①The warming rate of CNASA annual temperature near 46 years was 0.55 per 10 years, responding synchronously to global warming. Temperature increased remarkably in western Shaanxi, Gansu, Ningxia, most of Inner Mongolia, mid-northern Qinghai to Tarim basin, except for a decreased trend in Henan district of Qinghai. ②Most of the CNASA annual winter temperature was unstable, only that of Qinghai Plateau was relatively stable. ③The temporal changes of winter temperature are similar in the westerly of northwestern China. Transition from temperature-decreasing-type to temperature-increasing-type started at mid-1960s, an abrupt change happened in 1986, since then temperature entered a remarkably warming period until falling at the beginning of 2000s. Eighty percent of the first 10 hot years in regions as a whole appeared in 1990s and after, and ninety percent of the sub-regional hot years also appeared after 1990. The anomaly change of temperature had periods about 5-year. The present temperature is at high position viewed from a 20-year or more variation level. ④The spatial differences exist in winter temperature variation. The change is opposite in north and south of the Mongolia Xinjiang area and the Shanxi Gansu Ningxia Qinghai area, also opposite in west and east of the Mongolia Shanxi Gansu Ningxia area and the Qinghai Xinjiang area. ⑤There are 4 sub-regions of winter temperature anomaly divided by REOF analysis; they are the Mongolia Shaanxi Gansu Ningxia area, the plateau area, the northern Xinjiang area and the southern Xinjiang area. The plateau area has no obvious transition in winter temperature, other than the other areas with ascending transition at early 1970s and descending transition at mid-1990s. Besides, the abrupt change of annual temperature in the plateau area occurred in 1997, other than the other areas in 1986.

Key words: global warming, impact, winter mean air temperature, westerly in northwest China