報告書番号

V04015

タイトル（和文）

GIS連動型大気環境濃度予測システムの開発

タイトル（英文）

Development of GIS-based Air Quality Modeling System

概要 （図表や脚注は「報告書全文」に掲載しております）

建物近傍から排出される排ガス拡散を予測する場合，建物によるダウンウオッシュを考慮することが重要である。そのためには排ガス拡散に影響を及ぼす建物を判定しその形状パラメータを設定する必要があるが，都市部の多数の建物より適切な影響建物を抽出することは容易ではない。本研究では、GISを用いて市販の地図データベースより影響建物を自動的に抽出し，濃度を簡易に計算できるシステムを開発した。拡散計算用には日米で広く用いられている3種類の手法を組み込み、計算点や煙源などの条件をGISにより簡単に入力できる。また、影響建物の判定や形状パラメータの抽出は地図データベースより自動的に行う。風洞実験結果と比較した結果、予測結果はいずれも全体的に過小評価の傾向があるもののMETI-LIS方式では最大着地濃度を良く再現できた。また、煙源風下側で高濃度が生じるケースでは拡散パラメータ等に改良が必要であることがわかった。

概要 （英文）

In recent years, cogeneration systems have been installed for commercial uses in buildings such as hotels, hospitals and office buildings to reduce energy consumption and emissions of CO2. Most of these cogeneration systems exhaust the gases containing NOx emissions from the building's rooftop. When air-quality impact assessments for such facilities are undertaken, the building downwash effect on pollution dispersion around surrounding buildings must be considered. Some Gaussian dispersion models have been proposed that account for the building downwash effect by modifying plume rise algorithms or dispersion parameters. In these models, the dimensions of buildings around a pollution source that may affect plume dispersion need to be specified. In urban areas, however, it is difficult to specify building dimensions (widths and heights) because there are many buildings and some of them have complicated shapes. In this study, we develop an air dispersion modeling system which can take into account the building downwash effect by using a GIS (Geographic Information System) to specify building dimensions automatically. Three different types of dispersion model are incorporated in the system, and input parameters such as calculation grids, source location, emission rates and building dimensions can be configured readily by using a GUI (Graphical User Interface). To evaluate the performance of the system, a series of wind tunnel experiments simulating plume dispersion around models of buildings in the city of Shinagawa, Tokyo, were carried out. It was found that, overall, concentrations calculated by dispersion models were underestimated compared with those obtained by wind tunnel experiments, but for maximum ground level concentration, there was good agreement between theoretical and experimental values in some cases. In order to accurately predict the high concentrations that occur near the source buildings, modification of the plume rise algorithms and dispersion parameters are required.

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