Does urbanization increase diurnal land surface temperature variation? Evidence and implications

The diurnal land surface temperature (LST) variation is a primary characteristic of the effects of urbanization. However, no study to date has focused on changes in diurnal LST variation in urban environments. This paper investigates the effects of urbanization on landscape pattern and diurnal LST variation of Taipei City, using MODIS thermal images and SPOT multispectral remote sensing images over the 1994-2010 period. Supervised land-cover classifications were conducted to investigate decadal land-cover changes within the study area. A remote-sensing-based urbanization index was adopted as a quantitative measure of urbanization-induced changes in landscape patterns. Diurnal LST variations were assessed using MODIS Aqua satellite images. We found that the diurnal LST variation increases with the urbanization index, with the adverse effects of urbanization on the diurnal LST variation being more substantial in the earlier stages of urbanization. Increasing diurnal LST variation due to urbanization implies that urbanization is likely to result in a greater increase in urban heat absorption than in thermal inertia. This research provides insightful supporting evidence that, in mitigating UHI effects, measures that can reduce urban heat absorption such as urban parks, community green spaces, green roofs and cool (or permeable) pavements should be given higher priority.