Departmental Bulletin Paper 縁辺海モデルの現状と新たなモデリング手法

木田, 新一郎

74pp.67 - 75 , 2016-03-31 , 低温科学第74巻編集委員会
縁辺海の二つの特徴,海峡交換流と河川流入,に焦点を当て縁辺海の数値モデルの現状,手法,そ して進展についてレビューした.縁辺海の空間スケールは沿岸より大きいが海盆より小さい.海底地 形や海岸線の影響を強く受けつつ,二つの空間スケールで起こる力学が相互に作用する海域となって いる.縁辺海の鉛直・水平循環に伴う海峡交換流の力学過程をまず紹介し,西岸境界流を現実的に再 現する重要性をIsland Integral Constraint を基に議論した.また近年の高解像度化に伴って必要性が 高まっている河川流入を再現する新たな手法として層厚モデルを提案し,陸域から海洋の流れ場を シームレスに繋ぐことが可能であることを示した.This manuscript reviews current methods, knowledge, and progress of numerical models for the marginal seas. Marginal seas cover areas that are larger than a coastal scale but smaller than a basin scale. It is a region where dynamics occurring in both scales interact, under the influence of detailed structures in bottom topography and coastlines, which often requires high spatial resolution models to resolve. Two aspects are raised, where numerical models of marginal seas could improve, straits exchange flows and river outflows. The dynamics of the straits exchange flows that occur between marginal seas and open ocean are first discussed, with a focus on the overturning circulation. The importance of resolving realistic western boundary currents is then discussed based on the framework of the island integral constraint. This framework becomes especially important when the straits that connect the marginal seas and open ocean are narrow. Lastly, a new approach for modeling river inflows and ocean circulation simultaneously is introduced. The use of a layer model is shown to successfully capture the water flow from land to the ocean during extreme precipitation events.

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