The Charlotte Metropolitan Region (CMR), home to 2.5 million people in 14 counties, is exemplary of recent urbanization patterns in the developed world. Such rapid urban growth can significantly modify local climate through an intensification and expansion of the urban heat island (UHI) – characterized by warmer urban temperatures relative to the surrounding rural landscape. In particular, UHIs associated with large cities are known to vary in intensity from 1-10°C depending on local mean wind speed, relative humidity, cloudiness, time of day, and season. Low-level convergence induced by an UHI (much like a coastal sea breeze) initiates thunderstorms over the urban center and subsequently enhances precipitation (by 1-2 inches) up to 80 km downwind. Thus, UHIs impact local weather and climate, as well as urban hydrologic systems, air quality, and ecosystems.
Hyla cinerea
(American green tree frog)
UHI-induced changes in local climate also can have profound influences on the life histories of living organisms. Recent studies have reported that warmer urban areas are associated with earlier vegetation green-up, earlier flowering, and a longer growing season. However, little is known about how wildlife modifies its behavior in response to the warmer and wetter conditions often associated with large metropolitan regions. Our initial efforts focused on native, small-bodied, semi-aquatic organisms – specifically anurans (frogs and toads) – which may be particularly susceptible to small changes in UHI-induced temperature, humidity, and precipitation.
This project is documenting the structure, intensity, and seasonality of the Charlotte UHI temperature, humidity, and precipitation patterns, which are currently unknown. We also plan to develop simple a forecast method, whereby local UHI intensity can be anticipated 1-2 days in advance, so any mitigation efforts can be implemented in a timely manner. Lastly, we anticipate the results of this trans-disciplinary pilot project will highlight how local climate affects the persistence of species across the CMR, information which in turn will serve to inform our understanding of the effects of longer-term climatic changes on amphibians and biodiversity in general.
This line of research is a collaborative effort with multiple department faculty. Our efforts have been funded by generous grants from UNC Charlotte and the JMW Foundation, and we are currently pursuing additional funding from the National Science Foundation.
Relevant Publications:
Eastin, M. D., M. Baber, A. Boucher, S. Di Bari, R. Hubler, B. Stimac-Spalding, and T. Winesett, 2018: Temporal variability of the Charlotte (sub)urban heat island. Journal of Applied Meteorology and Climatology,57, 81-102.
Eastin, M. D., M. Baber, A. Boucher, S. A. Gagne, 2018: Spatial variability of the Charlotte (sub)urban heat island. To be submitted to the Journal of Applied Meteorology and Climatology.
Eastin, M. D., R. Hubler, 2018: Precipitation enhancement by the Charlotte (sub)urban heat island. To be submitted to the Journal of Applied Meteorology and Climatology.
Eastin, M. D., 2018: A synoptic climatology of the Charlotte (sub)urban heat island. To be submitted to the Journal of Applied Meteorology and Climatology.