Seventh Symposium on the Urban Environment


Estimation of urban heat fluxes in Shanghai from an airborne hyperspectral image: comparison of two models

Weidong Xu, King's College London, London, United Kingdom; and M. Wooster and S. Grimmond

Alteration of the surface energy balance by urbanization impacts urban warming, the growth of the boundary layer, and other biophysical processes. In this paper, turbulent sensible heat flux in a central urban area in Shanghai is determined using an airborne hyperspectral image with eight thermal bands. Two models are compared: (1) the Local-Scale Urban Meteorological Parameterization Scheme (LUMPS) and (2) an aerodynamic resistance method. LUMPS is implemented with a high resolution land cover map interpreted from the imagery and a map, along with local meteorological station data. The aerodynamic resistance method is implemented with information on the geometrical form of the study area and meteorological data. The sensible heat flux is calculated at 6 m and then resampled at 30, 90 and 500 m using three methods. Results indicate that LUMPS yields smaller internal variance compared to .the aerodynamic method because of the direct use of the temperature variance. Shadows slightly alter the net radiation and lower the temperature in the urban area, but the difference of sensible heat flux between the two methods is small at 500 m resolution.

Session 3, Energy Exchange, Water Balances and Anthropogenic Fluxes
Monday, 10 September 2007, 3:45 PM-5:45 PM, Kon Tiki Ballroom

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