ISODATA Clustering Approach for Mapping and Characterization of Surface Urban Heat Island Intensities Using Time Series of Remotely Sensed Land Surface Temperature and Land-Use/Land-Cover Products

This study evaluated spatial patterns and trends in surface urban heat island intensities (SUHIIs) across three major cities in Alabama, USA: Huntsville, Birmingham, and Mobile. Spatial expansion of developed areas and magnitudes and trends of SUHIs were mapped and quantified using land-use/land-cover (LULC) data from the National Land Cover Database (NLCD) and land-surface temperature (LST) products from the Moderate Resolution Imaging Spectroradiometer (MODIS), respectively. Our findings reveal urban expansion over all three study areas, but at varying rates and patterns. The ISODATA clustering approach using time series of LST data was able to map surface urban heat islands (SUHIs) as distinguished clusters of significantly (p=0.01) warmer surface temperatures as compared to their surroundings. Spatial distributions of the SUHI clusters over all three cities closely resembled spatial distributions of the developed areas. Our findings also revealed significantly different SUHI intensities (p=0.05) among the three study areas (during day and nighttime of summer and winter seasons). These findings indicate the ISODATA clustering approach using time series of satellite-derived LST products as a promising approach for local-scale mapping and characterization of SUHIs. Our findings also provide detailed insights for improved understanding of the spatial distributions and temporal variations of SUHI developments.