Author(s): Guangwei Huang
Linked Author(s): Guangwei Huang
Keywords: No Keywords
Abstract: Urbanization has resulted in inadvertent microscale and mesoscale changes in weatherand climate.The most noticeable product of the man-made micro-climate of cities hasbeen termed the 'urban heat island'.The principal characteristic of the urban heat islandis the increase of surface temperature within cities.In general,the central city surfacetemperature might be up to 10K warmer than the surrounding area.Analytical,numericaland field studies of this man's impact on climate have been conducted over the last severaldecades by numerous authors including R.Kimura(1972),who applied a linear theory toanalyze the atmospheric convection over a heat island,Myrup(1970),who proposed an energybudget equation to deal with this man-made problem,and Oke(1982,1987),Goldreich(1985),Draxler(1986),Tamai(1989),and F.Kimura(1991),who investigated the effects of land-useand anthropogenic heating in Tokyo metropolitan area.Although those studies have revealedmany aspects of the heat island phenomenon,the physical causation of the urban heat islandremains a partial enigma because of the complicated processes involved and of the rarity offield studies which identify the role of any individual cause.Recent increase in efforts in thisresearch field benefited from people's awareness of environmental issues and eagerness to livein a comfortable environment.In the present study,an analytical solution and numericalsimulations are combined to allow some conclusions to be drawn about effects of moisture androughness.To best of our knowledge,quite a number of studies in the literature employed a'dry model'to deal with the heat island problem,while in other studies,although a‘moistmodel'were employed,the role of moisture has not been sufficiently discussed.Consequently,there is a need to examine the role played by moisture and its interactions with other knownmajor factors which could develop and maintain the heat island.This study is part of alarge scale project undertaken to gain better understanding of the urban heat island.Theemphasis of this work is placed upon providing further insights into the effects of moistureand roughness.It should be noted that in this work,for the sake of simplicity,we restrictourselves to the non-rotating systems which implies the neglect of Coriolis forces.Althoughthe flow situation is idealized,it retains the essential physics of the urban heat island.
Year: 1993