A New 3D Urban Building Community Model for Earth System Modeling. Part II: Data and Comprehensive Evaluation

The urban building community model is an urban component of the Common Land Model (CoLM-UBCM) designed for weather and Earth system modeling, supporting high-resolution simulations from the meso to the global scale. In this study, a comprehensive global 500 m urban dataset for urban canopy models is developed and implemented in CoLM-UBCM, and the model is evaluated across multiple scales. The newly developed urban dataset includes detailed information on urban morphology, urban ecology, urban physical characteristics and urban human activities data, and incorporates temporal variability to support the dynamic evolution of urban areas. In addition, this dataset introduces a new three-dimensional morphological parameter called building height to side length ratio (H/L) to replace the conventional two-dimensional canyon height to street width ratio (H/W), enabling a more consistent representation of three-dimensional urban morphology and processes in CoLM-UBCM. We evaluate CoLM-UBCM across site, regional, and global scales in terms of radiative, turbulent, and anthropogenic heat fluxes, and compare the model with two International Urban Land Surface Model Comparison Projects as well as with Community Land Model Urban. The results indicate that CoLM-UBCM improves the simulation of key urban land-surface processes and generally performs better than the commonly used two-dimensional canyon model. These findings suggest that CoLM-UBCM is suitable for incorporation into weather and Earth system models for high-resolution urban simulations.