Improvements to the latent heat calculations in WRF multilayer urban parameterization

In urban environments, latent heat could be generated by anthropogenic heat release, evaporation over paved and vegetated surfaces. The Building Energy Model (BEM) in WRF calculates the anthropogenic heat released to the atmosphere by air conditioning systems to maintain a target temperature inside the buildings. BEM only accounts for sensible heat release producing an overestimation of the surface temperature in areas where high buildings are located. The type of air conditioning system can have an impact on the amount and type of heat emitted. Some AC systems work with water (cooling towers) and a large fraction of the heat emitted is latent rather than sensible. A cooling tower model is being incorporated in BEM for commercial areas to enhance WRF ability to simulate latent heat in urban areas. Evaporated water from rainfall events in urban surfaces is an additional important source of latent heat that is not taken into account in the multilayer urban scheme BEP/BEM. The methodology developed by Masson for the Town Energy Budget (TEB) scheme was incorporated in BEP to account for this source of latent heat. Additionally, urban canopy parameters from the Department of City Planning were assimilated in the model to improve the urban morphology in the boroughs of New York City (NYC) where NUDAPT data were not available. The simulations were evaluated using a dense weather station network for the summer of 2013 in NYC.