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都市域における熱輸送
菅原, 広史;山野, 満男;萩島, 理;成田, 健一
Permalink : http://hdl.handle.net/2115/73996
JaLCDOI : 10.14943/lowtemsci.77.87
KEYWORDS : 熱輸送;乱流;都市気候;Heat flux;Turbulence;Urban climatology
Abstract
都市の暑熱環境は，将来の気候変動下において重要性を増す社会的課題である．本報では都市キャノピー上における熱輸送について実例を用いて解説した．大気中で熱を鉛直上向きに輸送するのは暖気の上昇と冷気の下降であるが，大気成層が不安定な状態においてキャノピー上での熱輸送を担うのは，上昇する暖気であった．不安定性が強くなるほど，回数は少ないが強い乱流変動によって熱が輸送されていた．キャノピー上での暖気上昇が，日射で加熱された建物壁面での上昇流と関連している例を示した．
Turbulent heat transport in urban atmospheric boundary layer was investigated through the quadrant analysis with a field observation data. Heat flux above the buildings was dominated by upward ejection of warmer air in unstable stratification. In more unstable conditions, less frequent but stronger eddies accounted for a dominant portion of the turbulent heat transfer. An example was shown for a linkage in which the ejection above buildings corresponds to the buoyancy-driven upflow at the building walls.
Turbulent heat transport in urban atmospheric boundary layer was investigated through the quadrant analysis with a field observation data. Heat flux above the buildings was dominated by upward ejection of warmer air in unstable stratification. In more unstable conditions, less frequent but stronger eddies accounted for a dominant portion of the turbulent heat transfer. An example was shown for a linkage in which the ejection above buildings corresponds to the buoyancy-driven upflow at the building walls.
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