“源-汇”景观格局的热岛效应研究——以武汉市为例

论文基于2017年Landsat 8遥感影像,通过GIS技术选取城市地表温度、源汇景观密度、源汇景观贡献度和景观效应指数,结合地理空间分析和数理统计方法,分析了武汉市局部源汇景观格局对城市地表温度的贡献及其效应。结果表明：① 武汉市城区热岛(urban heat island, UHI)季节变化明显,夏季热岛强度大、范围广,呈“大”字型分布,工业集聚区和经济开发区产生的UHI更显著;② 武汉市城区平均地表温度(land surface temperature, LST)在距市中心约8 km处达到峰值后沿城乡梯度逐渐下降,呈现“倒钩型”特征,这一现象与景观密度变化密切相关;③ LST与源(正向)、汇(负向)景观密度存在极强相关性,不透水表面是城区热岛的主要贡献因子;④ 相同密度的水体和绿地,水体更具有削弱城市热岛效应的功能;⑤ 一般当汇-源景观面积比>0.89(汇区密度>0.47)时,局部景观格局对城市热岛有缓解作用,且局部汇区越集中缓解效果越显著。

Effects of source and sink landscape pattern on land surface temperature: An urban heat island study in Wuhan City

Due to its adverse impacts on urban ecological environment and the overall livability of cities, the urban heat island (UHI) phenomenon has become a major research focus in various interrelated fields. This study sought to evaluate the intensity of land surface temperature (LST) and the spatial pattern of source and sink landscape in the metropolitan areas of Wuhan City at a local scale, by examining urban surface temperature, landscape density of source and sink, contribution of source and sink, and landscape effect index. Landsat 8 OLI/TIRS data and geospatial approaches as well as statistical analysis were used to facilitate the analysis. The results shows that: 1) The UHI effect in Wuhan City has obvious seasonal changes and the intensity of UHI is strong in summer; the UHI generated by industrial agglomeration areas and economic development zones is more significant. 2) The mean LST of the city gradually declines along the urban-rural gradient after reaching the peak at about 8 km from the city center, showing a "barb-shaped" feature, which is closely related to the change of landscape density. 3) We found a significant strong correlation between mean LST and the density of source (positive) and sink (negative) landscape, and impervious surface is the main contributing factor of UHI. 4) With the same density of water and green spaces, water has greater potential of weakening the UHI effects. 5) Generally, when the areal ratio of sink-source landscape is greater than 0.89 (sink density greater than 0.47), the local landscape pattern has a mitigating effect on UHI. The more concentrated the local sink areas, the more significant the mitigation effect is.