Asymmetrical Change of Maximum,Minimum Temperature in Last 50 Years in Henan

The spatial and temporal change of maximum and minimum temperature and diurnal temperature range were analyzed based on the temperature data of 50 meteorological stations in Henan province from 1959 to 2008.The results showed that annual average maximum and minimum temperature increased non-symmetrically,the minimum temperature changed at the rate of 0.237℃/10y,and the maximum temperature changed at the rate of 0.053℃/10y.Annual average maximum and minimum temperature also changed asymmetric in majority area.The minimum temperature increased quickly in Northwest Henan and the maximum increased quickly in Central Henan,which resulted to diurnal temperature range reducing obviously in the east and northwest of Henan province.The Lowest annual average maximum temperature was in 1980s and the highest was in last 8 years,annual average minimum temperature kept low in 1960s,1970s,and 1980s,and the highest was in last 8 years.The highest diurnal temperature range was in 1960s,and the lowest was in last 8 years.Annual average minimum temperature changed abruptly in 1997,and no abrupt change in annual average maximum temperature.Annual average diurnal temperature range changed abruptly in 1974 and 1980.