Analysis of Evolving Surface Urban heat Island in NW Arkansas

Rapid urbanization leads to increase in land surface temperature (LST), deterioration in environmental quality, and ultimately global warming. Northwest Arkansas is currently going through a rapid urbanization process. Urban heat island refers to the elevated nigh time temperature of urban areas with respect to the more vegetative rural areas. The objective of this study was to estimate the LST, land use and land cover change and biomass areas, and to analyze the overall effect of vegetation and urbanization on LST of NW Arkansas in the last 10 years, from 1996 to 2006. Landsat 5 (path26, row35) image from March 2, 1996, April 17, 2001 and March 14, 2006 was used for urban heat island (UHI) analysis. The Landsat images were classified into five major classes namely forest, urban, soil, grass and water. The urban area in Benton and Washington County increased from 0.67% in 1996 to 2.00% in 2001 and 4.1% in 2006. Land surface temperatures were retrieved from thermal band of landsat-5 for the three different years. The mean temperature of the two-county area drastically increased from 9.24degC in 1996 to 12.11degC in 2001 and 18.78degC in 2006. The Normalized vegetation index (NDVI), which is an indicator of biomass decreased from 0.38 to 0.34 for this period. The rate of increase in the urban area and the decrease in NDVI in the last 10 years has altered the spring time temperature distribution. The mean temperature difference between forest and urban areas increased from 1.76degC to 3.3degC in the last 10 years. This information is critical in various fields such as atmospheric sciences and climatology for understanding the weather pattern, the environmental impact of urbanization, and to better manage our environment.