Local-Scale Urban Meteorological Parameterization Scheme (LUMPS): Longwave Radiation Parameterization and Seasonality-Related Developments

Recent developments to the Local-scale Urban Meteorological Parameterization Scheme (LUMPS), a simple model able to simulate the urban energy balance, are presented. The major development is the coupling of LUMPS to the Net All-Wave Radiation Parameterization (NARP). Other enhancements include that the model now accounts for the changing availability of water at the surface, seasonal variations of active vegetation, and the anthropogenic heat flux, while maintaining the need for only commonly available meteorological observations and basic surface characteristics. The incoming component of the longwave radiation (L down arrow) in NARP is improved through a simple relation derived using cloud cover observations from a ceilometer collected in central London, England. The new L down arrow formulation is evaluated with two independent multiyear datasets (Lodz, Poland, and Baltimore, Maryland) and compared with alternatives that include the original NARP and a simpler one using the National Climatic Data Center cloud observation database as input. The performance for the surface energy balance fluxes is assessed using a 2-yr dataset (Lodz). Results have an overall RMSE <34 W m(-2) for all surface energy balance fluxes over the 2-yr period when using L down arrow as forcing, and RMSE < 43 W m(-2) for all seasons in 2002 with all other options implemented to model L down arrow.