Influence of ground surface characteristics on the mean radiant temperature in urban areas
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The effect of variations in land cover on mean radiant temperature (T mrt ) is explored through a simple scheme developed within the radiation model SOLWEIG. Outgoing longwave radiation is parameterised using surface temperature observations on a grass and an asphalt surface, whereas outgoing shortwave radiation is modelled through variations in albedo for the different surfaces. The influence of ground surface materials on T mrt is small compared to the effects of shadowing. Nevertheless, altering ground surface materials could contribute to a reduction in T mrt to reduce the radiant load during heat-wave episodes in locations where shadowing is not an option. Evaluation of the new scheme suggests that despite its simplicity it can simulate the outgoing fluxes well, especially during sunny conditions. However, it underestimates at night and in shadowed locations. One grass surface used to develop the parameterisation, with very different characteristics compared to an evaluation grass site, caused T mrt to be underestimated. The implications of using high temporal resolution (e.g. 15 minutes) meteorological forcing data under partly cloudy conditions are demonstrated even for fairly proximal sites.
KeywordsSOLWEIG Surface temperature Gothenburg London
This work is financially supported by FORMAS – the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, H2020-EO-1-2014 Project 637519: URBANFLUXES and Newton Fund/Met Office Climate Services CSSP - China. Many thanks to William Morrison and the many others at University of Reading who maintain LUMA data collection, Barbican Estate and City of London Girls School for providing the data.
Open image in new window URBANFLUXES is co-financed by "HORIZON 2020" EU Framework Programme.
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