Baltimore Ecosystem Study Institute of Ecosystem Studies

2010 BES Annual Meeting Presentation and Poster Abstracts

Influences of Baltimore Parks on Air Temperature
Heisler, Gordon
Co-Authors: Gordon Heisler, Alexis Ellis, David Nowak, Ian Yesilonis, Eric Greenfield, John Hom, Emma Noonan, Hang Ryeol Na

Abstract: Urban forest and park management should account for effects on air temperature. However, urban tree influences on air temperature are difficult to estimate because of the complexity of urban environments and the inverse correlation of tree cover with built structures and impervious cover. We used measurements of air temperature at seven weather stations in or near Baltimore to develop equations to predict the difference in air temperature (T) between six of the stations and the downtown station as a reference point. The predictor variables included differences in land cover and topography between the six stations and the reference, along with the wind speed and cloud cover at the time of the measurement. The T equations were then used to create GIS maps of temperature difference across Baltimore and the surrounding region. The maps provide a means to illustrate air temperature variation due to tree cover, to changes in tree cover, to urban development, to topography, and to parks. Tree cover generally reduced temperature; impervious cover increased it. The GIS analysis indicates that after sundown on clear summer evenings when wind speed is low, large Baltimore parks, such as Leakin and Druid Hill, have average air temperatures 4 to 6 C (7 to 11 F) cooler than the warmest parts of the city. Part of the differences in temperature, 1 to 1.5 C (2 to 2.5 F) is caused by the higher elevation of these parks. The remainder of the temperature difference, 3 to 4.5 C (5 to 8 F), is a result of low impervious cover and high tree cover in the parks. The GIS maps also predict that parks cool adjacent neighborhoods out to one-half to one-full park width from the park. For Patterson Park, which is about 2000 ft wide from north to south, the cooling extended on average out to about 1000 ft from the edge of the park.