ESTIMATION OF LAND SURFACE TEMPERATURE OF CHENNAI METROPOLITAN AREA USING LANDSAT IMAGES

This study estimates the land surface temperature of the Chennai Metropolitan Area (CMA) by using open source softwares like Quantum GIS (QGIS) and Geographic Resources Analysis Support System (GRASS GIS). Landsat (TM5) reflected band such as Band 1-5 & 7 were used to classify land use and land cover. The Band 6 (emitted) was used to determine the land surface temperature (LST) for the study area. The radiance values were computed for all the bands. The band 3 & 4 were used for classifying the Normalized Difference Vegetation Index (NDVI). Landuse/Land cover pattern in CMA was carried out by onscreen digitization with visual interpretation technique by using Survey of India toposheet (1970) and with the available years of satellite data sets such as Landsat Thematic mapper (TM5) 2006 and 2009. The total percentage of vegetation, water bodies, settlements and unclassified or barren lands covers about 11.45, 29.88, 42.20 and 16.47 respectively. The NDVI value varies from - 0.42 to +0.74 and -0.38 to +0.69 during 2006 and 2009 respectively. The emissivity image was prepared and land use/land cover classes were identified and assigned with the corresponding emissivity values from 0.97 to 0.99. Land surface temperature was prepared for 2006 in which the values range from 18.5 0C to 34.560C and 19.20C to 35.90C for the year 2009. The study reveals that the nearby urban and surrounding areas have a temperature difference of 170C. Also it has been observed the dense settlement emits more heat when compared to water bodies and vegetation.