Synergetic interaction between spatial land cover dynamics and expanding urban heat islands.

Abstract

Inherent statistics of the surface temperature pattern were used to categorize urban heat islands (UHIs) for a tropical mega city and its satellite towns. Application of flexible threshold values for UHI zoning made this procedure independent of seasonal or locational influences. UHI zones for the years 1999, 2009, and 2019 were mapped from Landsat thermal bands by applying the mono-window algorithm. The parameters affecting the UHI intensity were rigorously investigated. Dynamics of land use land cover patterns provided in-depth insight into the spatiotemporal variability of UHI. The abrupt rises in localized surface temperature for every decade were recognized and thoroughly explained with the fall in fractional vegetation cover index and increase in normalized difference impervious surface index. The temporal nature of urban agglomeration and fragmentation of vegetation cover was quantified through landscape metric algorithms. The vegetation pattern and associated surface temperature fall were further used to evaluate the weakening of UHI intensity around major recreational zones. Substantial cooling by 0.938°C was noted on daytime, from urban built-up at a 50-m distance to the green parks. Differential rates of urbanization and associated magnification of UHIs were looked into separately for central urban and satellite town areas. The characteristics of built-up density and proximity to green areas were employed to strategize mitigatory measures for the constantly growing UHI problem. Urgent needs for sustainable policies and green landscaping were highlighted through multi-criterion analysis.