河口循環流と吹送流  [in Japanese] Estuarine Circulation and  Wind −driven Current  [in Japanese]

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Author(s)

Abstract

本研究は河口循環流が卓越する代表的な内湾の一つ,Chesapeake湾の実地形にPrinceton Ocean Modelを適用させ,潮汐と河川流量で基本場の河口循環流を再現した上に,代表的な風場を加えて,流動場,塩分場,そして乱流場の変動を調べた.風による塩分場の変動については湾内の成層構造と湾外の低塩分水の広がり面積に主な影響が現れる.湾内では風による成層構造の破壊あるいは弱化,湾外では風による低塩分水の接岸あるいは離岸が見られた.風による流動場の変動は湾内と湾外ともに顕著に現れた.しかし,これらの変動は河口循環流と吹送流の線形的な足し合わせでは十分に説明できない.その理由は,風による密度場の変動に伴う密度流の変動と,風による乱流場の変動に伴う流動構造の変動にあると考えられる.風による乱流場の変動は渦動粘性係数の増大に顕著に現れた.

Applying the Princeton Ocean Model to the bathymetry of Chesapeake Bay, we studied the relation between estuarine circulation and wind-driven current. First, the model reproduced the estuarine circulation with average river discharge and tide. Then, four wind fields with different directions but with the same amplitude were applied to the pre-established estuarine circulation. The wind-induced changes in the salinity field concentrate on the stratification inside the bay and the plume area outside the bay. Depending on the wind direction, the stratification inside the bay is destroyed or weakened while the plume area is moved onshore or offshore. The flow field also shows apparent responses to the wind. However, a linear superposition of wind-driven current on estuarine circulation cannot explain all the wind-induced variations in the flow field. Winds change the density field, which in turn also changes the flow field. Moreover, winds change the turbulent field, which changes the flow structures. A clear intensification of eddy viscosity coefficient by winds has been shown by this study.

Journal

  • Bulletin on Coastal Oceanography

    Bulletin on Coastal Oceanography 44(2), 117-127, 2007

    Coastal Oceanography Research Committee, the Oceanographic Society of Japan

Codes

  • NII Article ID (NAID)
    110007999374
  • NII NACSIS-CAT ID (NCID)
    AN10492259
  • Text Lang
    JPN
  • ISSN
    1342-2758
  • NDL Article ID
    8717066
  • NDL Source Classification
    ZM44(科学技術--地球科学--海洋・陸水・火山)
  • NDL Call No.
    Z15-533
  • Data Source
    NDL  NII-ELS  J-STAGE  NDL-Digital 
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