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Surface Heat Balance Analysis of Tainan City on March 6, 2001 Using ASTER and Formosat-2 Data
Earth Dynamic System Research Center, National Cheng Kung University, No. 1, Ta-Hsueh Road, Tainan 701, Taiwan
Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
Institute of Satellite Informatics and Earth Environment, Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan
Department of Landscape Architecture, National Chin-Yi University of Technology, Taichung, Taiwan
* Author to whom correspondence should be addressed.
Received: 1 September 2008; in revised form: 18 September 2008 / Accepted: 24 September 2008 / Published: 26 September 2008
Abstract: The urban heat island phenomenon occurs as a mixed result of anthropogenic heat discharge, decreased vegetation, and increased artificial impervious surfaces. To clarify the contribution of each factor to the urban heat island, it is necessary to evaluate the surface heat balance. Satellite remote sensing data of Tainan City, Taiwan, obtained from Terra ASTER and Formosat-2 were used to estimate surface heat balance in this study. ASTER data is suitable for analyzing heat balance because of the wide spectral range. We used Formosat-2 multispectral data to classify the land surface, which was used to interpolate some surface parameters for estimating heat fluxes. Because of the high spatial resolution of the Formosat-2 image, more roads, open spaces and small vegetation areas could be distinguished from buildings in urban areas; however, misclassifications of land cover in such areas using ASTER data would overestimate the sensible heat flux. On the other hand, the small vegetated areas detected from the Formosat-2 image slightly increased the estimation of latent heat flux. As a result, the storage heat flux derived from Formosat-2 is higher than that derived from ASTER data in most areas. From these results, we can conclude that the higher resolution land coverage map increases accuracy of the heat balance analysis. Storage heat flux occupies about 60 to 80% of the net radiation in most of the artificial surface areas in spite of their usages. Because of the homogeneity of the building roof materials, there is no contrast between the storage heat flux in business and residential areas. In sparsely vegetated urban areas, more heat is stored and latent heat is smaller than that in the forested suburbs. This result implies that density of vegetation has a significant influence in decreasing temperatures.
Keywords: ASTER; Formosat-2; land surface classification; storage heat flux
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Kato, S.; Yamaguchi, Y.; Liu, C.-C.; Sun, C.-Y. Surface Heat Balance Analysis of Tainan City on March 6, 2001 Using ASTER and Formosat-2 Data. Sensors 2008, 8, 6026-6044.
Kato S, Yamaguchi Y, Liu C-C, Sun C-Y. Surface Heat Balance Analysis of Tainan City on March 6, 2001 Using ASTER and Formosat-2 Data. Sensors. 2008; 8(9):6026-6044.
Kato, Soushi; Yamaguchi, Yasushi; Liu, Cheng-Chien; Sun, Chen-Yi. 2008. "Surface Heat Balance Analysis of Tainan City on March 6, 2001 Using ASTER and Formosat-2 Data." Sensors 8, no. 9: 6026-6044.