The Urban Building Community Model for Earth System Modeling: Model Formulation and Evaluation

Abstract A new urban canopy model is presented. Unlike the two‐dimensional (2D) canyon assumption used in most urban canopy models, this model proposes a three‐dimensional (3D) building community conceptualization. A key parameter, the building height‐to‐side‐length ratio (H/L), is introduced to replace the canyon height‐to‐width ratio (H/W) used in canyon models. Based on this 3D framework, new radiation transfer and turbulence exchange models are developed, both of which explicitly account for vegetation. A comprehensive representation of human activities is also incorporated. This paper introduces the new urban building community model (UBCM), focusing on the newly developed parameterizations of radiation, turbulence, and human activities. Furthermore, the model is evaluated using both idealized Monte Carlo experiments and simulations at two representative urban sites. The results demonstrate that the urban building community model accurately captures urban radiative and turbulent fluxes. This model is designed to better represent real‐world urban structures and to make optimal use of 3D morphology data. As an urban component of land surface models, it is suitable for weather and Earth system modeling and can be applied from mesoscale to large scales at high resolution. The corresponding urban data sets and comprehensive model evaluation are presented in the companion paper (W. Dong et al., 2026, https://doi.org/10.1029/2026MS005794 ).