Urban Heat Island Variations in Beijing Region in Multi Spatial and Temporal Scales

The annual variation of intensity of urban heat island(UHI),the impact of wind speed on UHI,and the diurnal variations of five urban sites in different seasons were studied in the paper by using the meteorological data.The result shows that annual average temperature appears an increasing trend in Beijing urban and suburb areas for the past 44 years.The intensity of UHI also shows an increasing trend.There is a negative correlation between the UHI and synchronous wind speed in Beijing region,and the decrease of wind speed led to the increase of UHI intensity.Results also show that diurnal change of UHI of Beijing is significant in 2005,the UHI is strong at nigh and week in the noon.The strongest UHI appears generally in winter seasons and the amplitude of UHI diurnal variation in winter is the largest,and the smallest in summer.