城市扩张对地表能量平衡的影响:以厦门为例

Urban Expansion and Its Impact on Surface Energy Balance:A Case Study of Xiamen

城市扩张与城市地表能量平衡的关系是研究城市气候的关键问题之一。该研究利用2000、2005、2011和2015年4期Landsat数据和对应卫星过境时刻的气象数据,借助土地利用转移矩阵方法,开展了厦门市近15年来城市扩张对地表能量平衡影响的分析。结果表明:(1)研究区近15年来耕地数量持续减少,林地和建设用地数量持续增加;裸地最容易变为其他土地利用类型,同时其他土地利用类型也最容易撂荒;建设用地主要由耕地转化而来,耕地主要转化为林地和建设用地。(2)地表通量的分布和大小与土地利用类型密切相关,其中水体和林地具有较高的净辐射和潜热通量,建设用地具有较高的显热通量、土壤热通量和人为热排放。(3)城市扩张引起地表反照率、地表粗糙度、热容量和透水能力等等的变化,使得潜热通量减少,而显热通量、土壤热通量和人为热排放增加。除了裸地以外,2000-2015年间其余4种土地利用类型变为建设用地时,净辐射是减少的。当裸地变为建设用地时,净辐射一直是增加的。

The relationship between urban expansion and urban surface energy balance is one of the key problems in the study of urban climate. This study have analyzed the impact of urban expansion on the surface energy balance in the last 15 years, based on a land use transfer matrix method and a heat-balance model using satellite remote sensing and ground meteorological data. Based on four Landsat remote sensing images on 2000, 2005, 2011 and 2015, combined with the This method was applied to Landsat TM and OLI/TIRS data for the daytime during 2000, 2005, 2011 and 2015 in Xiamen City.The results show that:(1) The agriculture area in Xiamen City has been decreasing continuously in the past 15 years, the forest and urban area has been increasing. The change rate of bare land is the highest, followed by the urban. The urban was mainly converted from agriculture, and the farmland was mainly converted into forest and urban.(2) The water and woodland have higher net radiation and latent heat flux, and the construction land has high sensible heat flux, soil heat flux and anthropogenic thermal emission.(3) The distribution and size of surface fluxes were closely related to the land use types, in which water and forest have high net radiation and latent heat flux, and the urban has high sensible heat flux, soil heat flux and anthropogenic heat discharge.(3) The change of surface albedo, surface roughness, heat capacity and water permeability caused by urban expansion leaded to the decrease of latent heat flux, and the increase of sensible heat flux, soil heat flux and anthropogenic heat discharge. In addition to the bare land, net radiation was reduced when the remaining four types of land use were converted to urban during 2000 to 2015. NET radiation has been increasing as the bare land becomes urban.