To a certain extent Urban Heat Island(UHI) influences the residents’ comfort and health. Understanding of how urban landscape affect the thermal environment is crucial for urban ecological planning and sustainable development.
Dr. KUANG wenhui etc., a team of researchers hosted from Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, measured and explained the relationship between urban landscape structure and thermal environment.
Ground and Remote Sensing-synchronized measurements on Land Surface Temperature(LST), surface radiation and heat flux components and atmosphere elements were implemented in Beijing, China, using portable infrared thermometers, thermal infrared imagers, Landsat TM and MODIS.
The spatial differences and the relationships between LST and the hierarchical landscape structure were revealed with in situ observations of surface radiation and heat fluxes. Large LST differences were found among various land-use/land-cover types, urban structures, and building materials.
Urban impervious surfaces was usually recognized the main causes on UHI. Synchronized measurements data revealed the intra-urban LST variations result largely from urban land-cover and building materials.
The differences were caused by different fractions of sensible heat or latent heat flux in net radiation. Urban impervious surface was primarily composed of sensible heat, with a Bowen ratio (H/LE) of 4.03. For urban green space, latent heat fraction (0.58) was higher than sensible heat because of vegetation transpiration.
Variations in building materials and urban structure significantly influenced the spatial pattern of LSTs in urban areas. By contrast, elevation and vegetation cover are the major determinants of the LST pattern in rural areas.
To alleviate urban heat island intensity, urban planners and policy makers should pay special attention to the selection of appropriate building materials, the reasonable arrangement of urban structures, and the rational design of landscape components.
This work was supported by the National Natural Science Foundation of China (41371408), the National Basic Research Program of China (2014CB954302; 2010CB950900), and National Key Technology R&D Program (2012BAJ15B02).
The related work has been published in Landscape Ecology (Kuang W H, Liu Y, Dou Y Y, et al. What are hot and what are not in an urban landscape: quantifying and explaining the land surface temperature pattern in Beijing, China. Landscape Ecology. 2015. DOI: 10.1007/s10980-014-0128-6.) .
