Study Of Regional Thermal Environments In China's World-class Urban Agglomerations Using

Urban agglomeration was an outcome of regional urbanization reaching relatively advanced stages of development.It has been worldwide-recognized that urban agglomeration shows clear scientific characteristic and advance in urban-regional spatial organization,the status of which is the main player in global urbanization.But with dense regional urbanization,urban agglomeration is being threatened by various regional eco-environmental stresses which are making it to be area tangled up in these troubles.To analyze whether urban agglomeration still could show their superiority in solving regional eco-environmental problems while perform their intrinsic advantage and importance in aspect of spatial organization.In this study,a new method based on metropolitan area as the basic unit to analyze UA's regional thermal environment(RTE)were proposed based on RS&GIS technology,by using land surface temperature(LST)products of MODIS from 2000 to 2015 and taking 3 China's world-class UAs as example.Results showed that during the period from 2000 to 2015,the metropolitan areas continuously expand in three urban agglomerations,and the closer metropolitan areas gradually integrated into each other in space due to the continuous intensification of the connections of various elements.At the same time,the urban agglomerations also played an important role in the socio-economic development of the urban agglomerations with a small consumption of land resources.However,it is worth noting that the excess heat in the metropolitan area was transferred to the surface urban heat island footprint(footprint)through the process of surface energy balance,which was further absorbed and dissipated.The surrounding suburban LST enhanced due to metropolitan area's influence,and at the same time,a large area of high-temperature area spatially integrated in urban agglomeration.In term of metropolitan area's influence,the average LST in metropolitan area's influenced range was raised 0.45? to 2.23? due to its surface urban heat island(SUHI).However in term of footprint,the main contribution is a large area of warming,but the temperature increase is small.Further studies have found that a large number of scattered built-up areas and towns in the fringe areas have connected or even superimposed the previously non-interfering footprints in urban agglomerations.Some natural surface may need to dissipate double or even multiple heat,and RTE is further deteriorated.The heat generated by the fringe area cannot be ignored,accounting for about 23% of the total heat in the metropolitan area.In addition,this heat will be superimposed on the footprint of the core area,resulting in an average increase of about 40% in the area of the core area and about 71% in the capacity of heat.In this study,the influence on RTE of development of UA was analyzed based on MA as the basic unit,as well as,the characteristic of UA's spatial expansion was emphasized.This is more consistent with actual condition in research of UA's thermal environment.Meanwhile,author hope that these findings could provide reference for the sustainable developmental research of UA all over the world.