Date of Award
Master of Science (MS)
Atmospheric and Earth Science
Thomas L. Sever
Walter Lee Ellenburg
Nature--Effect of human beings on., Urban heat island., Vegetation and climate.
In the quantification of Urban Heat Islands (UHI), anthropogenic modification of the rural area is an understudied yet vital area of interest. This research explores the influence of anthropogenic modification of vegetation in the rural reference area on surface urban heat island intensity (SUHII) by examining two research objectives. MODIS daily land surface temperature (LST), annual Cropscape landcover maps, and MODIS weekly smoothed NDVI are used. The first research objective is to characterize the different impacts of cultivated and natural vegetation on SUHII. Seasonal, diurnal, and regional differences are studied by quantifying the LST response to phenology changes in two contrasting domains, one predominantly surrounded by cultivated vegetation (Chicago) and the other predominantly surrounded by natural vegetation (Atlanta), from 2007 to 2018. The influence of cultivated vegetation is more pronounced during the daytime in spring and fall than during the summer or at night, resulting in up to a 6 oC underestimation of SUHII relative to natural vegetation. This underestimation of SUHII in spring and fall is linked to reduced vegetative activity in cultivated areas during those seasons. Chicago, at a higher latitude and surrounded by cultivated land, resulted in larger changes in SUHII and NDVI than Atlanta over the growing season. Further characterizing the seasonal relationship between phenology and SUHII with Fourier approximations revealed unique SUHII/ΔNDVI curves for each species as well as between the two domains. These unique curves can potentially be used to develop regional vegetation patterns, enhancing city-to-city and region-to-region UHI comparisons. The second research objective is to characterize the impact of different LST responses of cultivated and natural vegetation on SUHII as a result of the timing and intensity of extreme heat. The spring and summer 2012 heatwaves were studied by comparing them with the 2007-2018 multi-year mean. The spring heatwave increases the underestimation of SUHII by cultivated vegetation up to 2.8 oC, but only negligible differences were found during the summer heatwave. The contrasting impact on SUHII between spring and summer heatwaves is linked to the increased difference in vegetative activity between cultivated and natural vegetation during the spring heatwave. Daytime SUHII was impacted more than nighttime SUHII and regional differences were minimal. The results of this research show that the impact of anthropogenic modification of vegetation on SUHII is greatest during the spring and fall and the smallest during summer even during periods of extreme heat; therefore, it is recommended that future UHI studies take into account the differences between anthropogenically modified and natural vegetation when choosing the rural reference area, especially for comparative seasonal studies.
Dornath-Mohr, Michelle, "The impact of anthropogenic modification of rural areas on surface urban heat island intensity" (2020). Theses. 312.