Study of Thermal Environment of Hefei City based on TM and GIS

Based on TM data,the land surface temperature(LST) and normalized difference vegetation index(NDVI) on 5th October 2007 were retrieved quantificationally in this paper.Besides,along with the theory of fractal dimension of urban form and GIS technology,the spatial pattern of thermal environment and the relationship between land use type change and their corresponding thermal environment classes in Hefei region were analyzed.The results suggested that:the intensity of urban heat island(UHI) in Hefei was relative stronger(weaker) in southeast(northwest) area,and the core of UHI did not arise in central Hefei city.The LST has a significant linear-negative correlation with NDVI(the correlation coefficient is-0.734),the LST would decreased 0.93℃ correspondingly if NDVI increased 0.1.The weighted heat effect index(WHI) of urban area is 1.14,which made the strongest positive effects on UHI of Hefei;while the WHI of farmland is-0.51,which made the strongest negative effects on UHI of Hefei.These results indicated that the farmland may play a critical role in all kinds of thermal environment classes.This work provided some scientific basis for reduction of UHI effect in Hefei.