Improving the Representation of Latent Heat Fluxes on Operational Forecast Models for Beijing, China

Model performance assessment for operational purposes of the WRF/BEP+BEM model indicates underestimation of latent heat fluxes and over-estimation of sensible heat fluxes and surface temperatures in the urban areas for summer seasons in Beijing, China.  A new parameterization to account for anthropogenic latent and sensible heat fluxes from buildings has been incorporated in WRF/BEP+BEM based on evaporative cooling technologies (i.e. cooling towers, CT). Observational data of a meteorological tower in Beijing and surface stations are used to evaluate the updated model for the 2015 summer season in Beijing. Average latent heat flux is increased by 60% in nighttime and 12% in daytime, while sensible heat flux is reduced by 3% in nighttime and 9% daytime when CTs are introduced. Additionally, the model performance is improved when CTs are introduced in dry days over rainy days. In the boundary layer, atmospheric stability is modified in the lower levels when the anthropogenic partition heat is modified due to suppression of the sensible heat flux.  Overall, the model performance is significantly improved by CTs even though the simulated latent heat flux is still smaller than observations.