Evaluation of spatial and temporal variations of surface urban heat island effect across conterminous United States using remote sensing.

Abstract:

The term “Urban heat island (UHI)” describes urbanized areas that are hotter than nearby non-urbanized and natural areas. These heat islands are formed due to the heat accumulations over constructed surfaces that are necessary to accommodate growing populations. UHI effect can have multiple impacts on the Earth’s environment and human populations. The goal of this study was to evaluate temporal (seasonal and diurnal) and spatial variations in the distribution and magnitude of UHI as recorded in satellite derived Land Surface Temperatures (LSTs) across the conterminous United States. Magnitude of UHI was estimated as LST variability between two Land-Use /Land-Cover (LULC) classes: impervious surface areas and adjacent natural surfaces. LULC data from National Land Cover Database (NLCD) were used to spatially locate and extract impervious surface areas and natural surfaces. Day and night time seasonal LST averages for winter and summer months were derived from Moderate Resolution Imagine Spectroradiometer (MODIS) bi-monthly LST data products. Our findings indicate significant (p=0.05) variability in UHI magnitude seasonally (winter vs summer) as well as diurnally. On average UHI magnitudes were higher during day time as compared to night time. During our study period (200 – 2018) the highest UHI magnitudes was reported as 10.9⁰C during summer day time of 2009 and the lowest of 3.1⁰C reported for winter night time of 2000. Spatial variations in UHI magnitudes were observed among impervious surface areas of variable spatial extents. However, further analyses are necessary for better understanding of the urban developments on UHI effect. However, findings of this work indicate the high potential of satellite derived LST estimates to quantify UHI effects in terms of surface warming.