Abstract
This study compared Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) surface temperature data within situmeasurements to validate the use of ASTER data for studying heat islands in urban settings with complex spatial characteristics. Eight sites in Changwon, Korea, were selected for analyses. Surface temperature data were extracted from the thermal infrared (TIR) band of ASTER on four dates during the summer and fall of 2012, and correspondingin situmeasurements of temperature were also collected. Comparisons showed that ASTER derived temperatures were generally 4.27°C lower than temperatures collected byin situmeasurements during the daytime, except on cloudy days. However, ASTER temperatures were higher by 2.23–2.69°C on two dates during the nighttime. Temperature differences between a city park and a paved area were insignificant. Differences between ASTER derived temperatures and onsite measurements are caused by a variety of factors including the application of emissivity values that do not consider the complex spatial characteristics of urban areas. Therefore, to improve the accuracy of surface temperatures extracted from infrared satellite imagery, we propose a revised model whereby temperature data is obtained from ASTER and emissivity values for various land covers are extracted based onin situmeasurements.
Highlights
Cities all over the world are experiencing more common urban heat islands (UHIs), whereby urban settlements are hotter than rural areas because of the rapid increase in artificial land cover such as asphalt [1,2,3,4]
We compared surface temperatures measured onsite and via Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) images during both the day and the night to validate the accuracy of surface temperature satellite imagery used frequently in UHI studies
The results indicated that surface temperatures from field measurements were higher than those derived from satellite images during the day, while the opposite pattern was observed during the night, except for in a few locations
Summary
Cities all over the world are experiencing more common urban heat islands (UHIs), whereby urban settlements are hotter than rural areas because of the rapid increase in artificial land cover such as asphalt [1,2,3,4]. Temperature increases from UHIs greatly increase energy consumption from the use of coolers [9, 10] and the aggregated effects from UHIs can cause changes in urban ecosystems [11]. Surface temperature data derived from satellite images can be used to assess characteristics of UHIs such as how temperatures vary across the canopy layer of roofs and other surface features [19,20,21,22,23] or how temperatures are related to the surface energy balance [24,25,26,27,28]. Satellite data can be used to analyze the general features of atmospheric UHIs in urban areas [29, 30]
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