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Title: Large Eddy Simulationを用いた層積雲の崩壊過程についての数値的研究
Other Titles: A Numerical Study on Dissipation Mechanism of Marine Stratocumulus Using Large Eddy Simulation
Authors: 三浦, 知博  KAKEN_name
石川, 裕彦  kyouindb  KAKEN_id  orcid (unconfirmed)
Author's alias: MIURA, Tomohiro
ISHIKAWA, Hirohiko
Keywords: 層積雲
Large Eddy Simulation
Marine Boundary Layer
Issue Date: 20-Oct-2011
Publisher: 京都大学防災研究所
Journal title: 京都大学防災研究所年報. B = Disaster Prevention Research Institute Annuals. B
Volume: 54
Issue: B
Start page: 333
End page: 346
Abstract: 層積雲の崩壊過程についてLarge Eddy Simulation(LES)を用いたいくつかの数値実験を行った。層積雲を含む境界層大気が赤道方向へ移流される状況を仮定した実験設定であり, 層積雲の崩壊, 積雲の卓越までの遷移過程を扱う。まず, 先行研究と同様の2次元LESと3次元LESとの結果を比較した。定性的な結果は同じであったが, 2次元の結果は地表面付近の風速, 海面からのフラックスが小さいことが分かった。次に層積雲の崩壊過程に大規模沈降流の弱まりが与える影響を調べた。大規模沈降流の弱まりの程度で分けた3ケースの実験を行った。結果として大規模沈降流が弱まることは層積雲の崩壊過程を促進することが分かった。パッシブスカラーを用いて境界層内の詳細な輸送構造を調べたところ, 沈降流の弱まりの程度が大きいほど境界層上端でエントレインメントにより取り込まれた空気塊は境界層下層まで到達しにくいことが明らかになった。
The dissipation mechanism of marine stratocumulus has been studied using Large Eddy Simulation which can precisely estimate turbulent transfer. According to previous study, numerical experiment was set assuming that air mass is advected from subtropical eastern Pacific toward equator. First, the comparison of the results using 2D LES with 3D LES has done. It's found that both result are same qualitatively. But, 2D LES included problems concerning with wind velocity. Secondly, the role of large-scale subsidence weakening on the Sc to Cu transition has been studied. This experiment suggests that the large scale subsidence weakeness is important as well as sea surface temperature increase . Finally, the role of large-scale subsidence weakening on the decoupling has been studied with passive scalar. As a result, the weakening LS-subsidence has promoted decoupling because turbulent transfer due to radiative cooling occurred at the top of Sc deck haven't reached lower part of boundary layer.
Appears in Collections:Vol.54 B

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