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Biophysical effects of land use on the surface climate

Speaker: Xuhui Lee, Professor of Meteorology, Yale University
Series: CEE Departmental Seminars
Location: Bowen Hall Auditorium
Date/Time: Monday, November 5, 2012, 4:30 p.m. - 5:30 p.m.

Abstract:

Xuhui Lee

The biophysical effects of land use activities (deforestation, tree planting, urbanization) arise from changes in surface albedo, surface roughness, and evaporation, and are important to the climate system at both the global and the local scale. The global consequence of albedo change has been extensively studied with climate models. The albedo change, along with energy redistribution associated with changes in surface roughness and evaporation, also drives changes in the local climate, but the net effect of these factors is uncertain. In this study, a surface energy balance model is used to isolate the contribution of local radiative forcing to surface temperature response from the dynamic feedback resulting from energy redistribution in the atmospheric boundary layer. The model prediction is supported by a “site-pair” analysis in which forest eddy covariance tower data are compared with the data collected at nearby weather stations, with the latter used as proxies for small cleared land. Results show that the effect of deforestation on local surface temperature is highly dependent on latitude. These biophysical considerations are also discussed in reference to efforts to mitigate urban heat island in Chicago and to a project on the Lake Taihu Eddy Flux Mesonet in China.