Web-Enabled Landsat Data Time Series for Monitoring Urban Heat Island Impacts on Land Surface Phenology

Urbanization increases the impacts of cities on the natural environment, in part by altering local environmental conditions. The Web-Enabled Landsat Data (WELD) archive (2003-2012) provides an opportunity to analyze the impacts of urbanization and urban heat islands (UHIs) on vegetation dynamics in and around cities. Here, we modeled the WELD normalized difference vegetation index (NDVI) product as a convex quadratic function of thermal time and derived land surface phenology (LSP) metrics to investigate the influence of UHIs on LSP along an urban-rural gradient and to characterize the response of vegetation to urbanization for two cities in the U.S. Northern Great Plains. Results show that for perennial vegetation, proximity to city center is positively associated with increased duration of growing season in thermal time. We found a linear relationship between the modeled rate of vegetation green-up and the peak height of NDVI for developed and forest pixels and after croplands were converted to developed land covers.