On the Environmental Sensible/Latent Heat Fluxes From A/C Systems in Urban Dense Environments: A New Modeling Approach and Case Study

Recent trends for denser cities and associated levels of human activity reflected in energy demands are requiring new ways for quantifying human environmental impacts in cities. There is little information on human-induced environmental heat fluxes from very dense urban environments, and far less information on the anthropogenic sensible/latent heat flux partition. To address this, a surface energy model that takes into account evaporation from impervious surfaces and from cooling towers from buildings was implemented in the multilayer urban canopy model (BEP+BEM) of the Weather Forecasting Research (WRF) model to estimate the overall sensible/latent heat fluxes from urban surfaces and from air condition (A/C) systems from buildings in complex urban environments. The scenario used as case study was New York City (NYC) during summers (2010 & 2013). Urban canopy parameters from the Department of City Planning of NYC were assimilated into WRF with BEP+BEM at 250 meters horizontal resolution to have an accurate representation of the city topology. The modeling approach was calibrated with surface weather stations in NYC showing general good agreement with slight tendency to overestimate maximum temperatures and underestimate moisture content at nighttime. The A/C component was estimated in 150W/m² latent heat due to cooling towers, and close to 40 W/m² in sensible. Evaporative cooling technology diminishes between 80 and 90% the amount of sensible heat which is transformed into latent heat. Impacts of anthropogenic in the Planetary Boundary Layer (PBL) reflect warm season increases in the PBL height, and significant increases of atmospheric instability.