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Comparison of mean radiant temperature from field experiment and modelling: a case study in Freiburg, Germany

Chen, Yung-Chang, Lin, Tzu-Ping, Matzarakis, Andreas
Theoretical and applied climatology 2014 v.118 no.3 pp. 535-551
carbon dioxide, case studies, field experimentation, models, prediction, surface temperature, wind speed, Germany
Mean radiant temperature (T ₘᵣₜ) based on two measurement methods and outputs from three models are compared in this study. They are the six direction radiation method, globe thermometer method, RayMan model, ENVI-met model and SOLWEIG model. The comparison shows that globe thermometer method may overestimate the T ₘᵣₜ since wind velocity is a key variable in the estimation based on this method. For better estimation, T ₘᵣₜ measured by the globe-thermometer method be corrected by the imported wind speed (stable, low and assuming wind speed) and validated by the six-direction radiation method. The comparison of models shows that the RayMan model’s evaluation of T ₘᵣₜ involving global radiation with fine time resolution was better than the corresponding evaluations under the other two models (ENVI-met and SOLWEIG) in this case. However, the RayMan model can only assess T ₘᵣₜ for a one-point one-time context, whereas the other two models can evaluate two-dimensional T ₘᵣₜ. For two-dimensional evaluations of T ₘᵣₜ, SOLWEIG have a better prediction of T ₘᵣₜ than ENVI-met, and ENVI-met can simulate several different variables, which are wind field, particle distribution, CO₂ distribution and the other thermal parameters (T ₐ, surface temperature and radiation fluxes), that SOLWEIG cannot.