Further Study of Temperature Change in Northwest China in Recent 50 Years

Some new characteristics of the surface air temperature change in Northwest China in recent 50 years are shown based on the monthly data from 1960 to 2005 of 135 stations.The data is the most complete station data set in Northwest China,which are processed by the National Meteorological Information Center recently.The new features include: ①Annual and seasonal average temperature in the whole Northwest China show increasing trend except that the summer average temperature in south Shaanxi shows decreasing trend.The area with the highest warming rate in winter and autumn is located in zonal region,which stretches from west Tarim Basin to Hexi corridor from 35°N to 40°N.Annual mean surface air temperature in Northwest China as a whole has a warming rate of about 0.37℃/10a,and the warming rate in winter can reach 0.56℃/10a.Whether the annual or the seasonal warming rates of mean surface air temperature in Northwest China is higher than the average values of the whole China.②The mean surface air temperature in winter and annual in Northwest China has been increasing most obviously since middle 1980's in recent 50 years.However,the temperature in spring,summer and autumn did not show significant increasing trend until in middle 1990's.③The anomaly of annual average temperature has the characteristic of spatial consistency in the whole Northwest China,and then it has adverse variation trend in south and north part,and last there is particular character of mean temperature change in south Shaanxi compared with that in the other areas of Northwest China.The characteristic of spatial consistency is in more and more obvious status in recent 50 years and the asynchronous trend of temperature change between south Shaanxi and the other areas is decreasing.④There are three representative annual temperature anomaly areas: southern Xinjiang-Qingzang Plateau,northern Xinjiang,and east of Northwest China.Further analysis suggests that the secular trend of mean annual temperature show distinct increasing trend in the first two temperature anomaly areas,and fluctuant increasing in the last temperature anomaly area.