The University of Tokyo · Environmental Science
Professor Hongyuan Jia's research lab specializes in atmospheric boundary-layer modeling and micrometeorology, with a focus on footprint modeling for complex urban environments. The lab develops advanced numerical methods—such as adjoint-based backward-Eulerian models—to accurately estimate concentration and flux footprints under varying atmospheric stability and urban surface heterogeneity. Their work integrates wind tunnel experiments with computational simulations to validate models and improve the understanding of pollutant dispersion and surface-atmosphere exchange in cities. The lab also emphasizes the impact of sensor height and wind direction on footprint heterogeneity in urban canopies.
Figures are computed from collected data and may differ slightly.
This study developed a backward-Eulerian footprint modelling method based on an adjoint equation for atmospheric boundary-layer flows. In the proposed method, the concentration footprint can be obtained directly by numerical simulation with the adjoint equation, and the flux footprints can be estimated using the adjoint concentration based on the gradient diffusion hypothesis. We first tested the proposed method by estimating the footprints for an ideal three-dimensional boundary layer with diff
Abstract This study addresses the need to investigate footprint function features in urban areas and establish a validation database for numerical methods. Concentration and its flux footprints of a block-arrayed urban model were measured in a wind tunnel with a neutrally stratified boundary layer. The velocity and concentration were simultaneously measured by an X-probe hot wire anemometer and a fast-response flame ionization detector to evaluate the vertical flux. Experimental results highligh
This study investigates the footprint distributions at various measurement positions in an urban array model, considering two incident wind directions, 22.5° and 45°, by a wind tunnel experiment. The airflow velocity and tracer concentration are simultaneously measured by an X-probe hot wire anemometer and a flame ionization detector, respectively, to assess the vertical flux of tracer gas. The experiment findings reveal a unified relationship between footprint distributions and measurement heig
Abstract This study addresses the need to investigate footprint function features in urban areas and establish a validation database for numerical methods. Concentration and its flux footprints of a block-arrayed urban model were measured in a wind tunnel with a neutrally stratified boundary layer. The velocity and concentration were simultaneously measured by an X-probe hot wire anemometer and a fast-response flame ionization detector to evaluate the vertical flux. Experimental results highligh
Abstract This study developed a backward-Eulerian footprint modeling method based on an adjoint equation for the urban environment, which has complex terrains and a high degree of heterogeneity. In the proposed method, the concentration footprint can be obtained directly by simulating the equation, and the flux footprints can be estimated using the adjoint concentration based on the gradient diffusion hypothesis. We first tested the proposed method by estimating the footprints for an ideal three
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