Integrated Microscale Modeling of Urban Atmosphere and Surface Energy Balance in High-Rise Building Blocks: Evaluation on an Extreme Heat Wave Event

Microscale meteorological models have been continuously improved and are used widely to interpret complex flow and thermal environments over real urban areas. The dynamic effects of urban buildings have been realistically represented by virtue of high resolution geographic information system (GIS) data and enhanced computational power. However, realistic urban heating is still required to be represented in the microscale models. This study aims to develop and evaluate the integrated microscale modeling system of atmosphere and surface energy balance in high-rise building blocks during an extreme heat wave period. The integrated microscale modeling system consists of a Computational Fluid Dynamics (CFD) model and an urban surface energy balance model. The CFD model solves the Reynolds-averaged Navier-Stokes equation with a Boussinesq approximation. The urban surface energy balance model calculates microscale urban physical processes of short- and long-wave radiative transfer, turbulent heat exchange, and subsurface heat conduction. The predicted urban surface temperatures are incorporated with the wall function of the CFD model. Intensive field measurements have been conducted over high-rise building blocks in Seoul, Korea during an extreme heat wave period on 5-6 August 2019 and obtained a unique dataset of urban surface and meteorology from multiple in-situ and mobile measurement platforms. The microscale modeling is under way for the extreme heat wave days over the high-rise urban area of 2000×2000 m² with a grid resolution of 2 m. The simulated meteorology and surface temperatures will be compared against the intensive measurements to evaluate the model’s capability in simulating spatial and temporal variation over the complex real urban area. The impacts of realistic urban heating on in-canyon urban flow and thermal environments will be discussed in detail.