Impacts of the Charlotte (North Carolina) Urban Heat Island on Local Precipitation, Biodiversity, Human Health, and Energy Use

For the first time in history, more than 50% of the global human population lives in cities and towns. This urban demographic transformation has been recent, rapid, and spatially extensive. One example is the Charlotte Metropolitan Region (CMR), whereby, between 1976 and 2006, the developed land cover increased by over 500%, surpassing population growth and resulting in a disjointed low-density development pattern across the region. Such rapid urban growth can significantly modify local climate through an intensification and expansion of the urban heat island (UHI), which in turn can impact local weather patterns, air quality, ecology, and resource consumption. The aim of this study is to (1) document the diurnal and seasonal variability of Charlotte's canopy-level UHI from a mesonet of surface weather stations, (2) characterize the UHI spatial variability during two intensive observation periods when the mesonet was increased five-fold, and (3) relate this variability to local precipitation patterns, human health risks, biodiversity, and energy use.

Five years of hourly observations from 12 standard surface weather stations spread across the urban, suburban, and rural landscape of the CMR revealed that the Charlotte nocturnal UHI frequently exceeded 3ºC on clear, calm nights throughout the late-fall, winter, and early-spring when regional foliage was limited. The maximum nocturnal UHI was 9.2ºC. In contrast, the daytime UHI often exceeded 1-2ºC (maximum of 5.2ºC) on clear summer afternoons, and such events were frequently followed by enhanced evening thunderstorm activity across the region. Details concerning UHI spatial structure, as well as potential impacts on biodiversity, human health, and energy use, will be presented at the conference.