ON CHANGES OF CHINA’S MAXIMUM AND MINIMUM TEMPERATURES IN 1951-1990

Based on China's observational data in 1951-1990,after minimizing the possible biases caused by station relocation and urban heat island,the spatial and temporal distributions of trends for maximum and minimum temperatures are studied.The results show that increasing trends of maximum temperatures are in the areas west to 95°E,and north to the Huanghe (Yellow) River,while decreasing trends exist in eastern China south to the Yellow River.Minimum temperatures are generally increasing throughout China,with dominant warming trends at the higher latitudes.This resulted in very obvious decreasing trends in diurnal temperature ranges.The periodic cycles are consistent between the maximum and minimum temperatures,but asymmetric trends are very obvious.The significant increase of minimum(nighttime) temperatures reflects the evidence of enhancement of greenhouse effect.Further analysis shows that the changes of maximum and minimum temperatures are mainly related to sunshine duration and atmospheric water vapor content.