Spatial-temporal characteristics of urban heat island effect change of Nanjing city and its relation with land use change

How to analyze the change of urban heat island effect(UHIE) and its quantificational relations with land use is one of the difficult problems in the study of the formation mechanisms of its driving forces.This paper analyzes spatial-temporal characteristics of UHIE intensity and scope change of Nanjing city and its relations with land use change using remote sensing and meteorological data.The results indicate that both scope and intensity of UHIE have been increasing since 1985.Viewing from the change of intensity,the changing tendency of annual mean temperature has been going up but the changing tendency of Nanjing city is different from its suburban county of Liuhe,being 0.16℃ during 1986~1990,0.18℃ during 1991~1995 and 0.262℃ during 1996~2000.From the change of scope,the scope of four-level UHIE in Nanjing built-up area has added 107.88 km2 since 1985.There were two core districts of UHIE in 1985,the biggest one was distributed in Xinjiekou,Fuzimiao and places south of it,the other was in the vicinity of railway station and bus station in Nanjing city.There were three intense UHIE centers in 2000,two of which were in the same positions of the major two in 1985,but their scope increased compared with the former ones.The other one was in the industrial district of Dachang and Pukou.The index of UHIE is used to probe into the spatial difference of UHIE evolution during 1985~2000,the six districts are in the order of DachangYuhuaShixiaQixiaPukouJiangning.The major characteristic of land use in Nanjing city is the conversion of natural landscape such as cultivated land,greenbelt and water to man-made landscape.The change of vegetation cover,soil moisture and artificial heat because of land use change is the main reasons of the effect of land use change on urban heat island.According to NDVI,TVDI,artificial heat and LST of every kind of land use,the temperature effect index is provided to evaluate the effect of land use change on urban heat island.The results indicate that land use change in Nanjing city leads to more extensive and intensive urban heat island.The region where urban construction land expands most quickly is also where the urban heat island increases most quickly and the expansion of urban construction land doesn't accord with the increase of urban heat island in space.