Introducing the COSMO model with TEB urban canopy scheme: coupling strategy and comparison with simpler TERRA_URB parameterization

Numerical weather prediction (NWP) models, coupled with urban parameterizations, play a crucial role in understanding and forecasting meteorological conditions within urban environments. Urban parameterizations vary in complexity, ranging from simplified slab models to complex multi-layer urban canopy models. In the mesoscale NWP model COSMO, only one urban parameterization, TERRA_URB, is available, which describes the city as a flat surface with modified surface parameters in accordance with the urban canyon geometry. In this study, we have coupled the latest version 6.0 of the COSMO model with a more sophisticated urban canopy model, TEB (Town Energy Balance), which explicitly simulates the energy exchange inside the urban canyon. Here, we present the coupling approach and assessment of model’s sensitivity to urban schemes of different complexity (TEB and TERRA_URB) over the Moscow region for August 2022. Despite using the same external parameters for both schemes, simulations demonstrate notable differences in temperature simulations, with TEB generally producing lower nighttime and morning temperatures. This leads to a greater underestimation of the urban heat island intensity in TEB when compared with the observations. The simulated surface albedo, as well as cell-averaged sensible and latent heat fluxes, differ slightly between the parameterizations and could not explain revealed temperature differences. We attribute the observed temperature discrepancies to the different descriptions of heat conductivity and storage within urban surfaces. Although there are no clear advantages to using a more complex parameterization in terms of model errors, TEB opens up more opportunities to refine input parameters and take into account additional processes. Future research involves the improvement of TEB by incorporating a module of green infrastructure into the urban canyon through coupling with COSMO’s land surface model and by setting the Building Energy Model specifically for Moscow conditions.
The study was supported by Russian Science Foundation Project no. 24-17-00155.