地形による沿岸捕捉波の散乱に関する数値実験  [in Japanese] Numerical Experiments on Scattering of Coastal-Trapped Waves by Topography and Bays  [in Japanese]

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Author(s)

Abstract

海岸・海底地形が沿岸捕捉波の伝播におよぼす影響について, 簡単な地形を用いた数値実験により研究した。狭い陸棚を持つ深い湾へ伝播する場合には, 岸に沿う風で発生した内部ケルビン波型の沿岸捕捉波は, ほとんど分裂せず湾内へ伝播する。一方, 陸棚が湾口の外側まで張り出す浅い湾へ伝播する場合には, 沿岸捕捉波は湾内へ進入する内部ケルビン波と, 陸棚に沿って湾口沖を伝播する陸棚波型沿岸捕捉波に分かれて, 波形が変化した。これらの特徴は, 沿岸捕捉波による日本南岸各地での潮位変動を良く説明している。陸棚幅が広い場合には, 岸に沿う風により陸棚波が発生するが, 浅い湾の湾口で分裂せずに陸棚端に沿って伝播した。また, 湾口の陸棚に沿って伝播する陸棚波型沿岸捕捉波は, 陸棚の途切れを跳び越えて伝播し, その振幅は途切れ幅が狭くなるに従い大きくなることが確認された。さらに, 湾の幅がロスビーの内部変形半径の2倍より狭い場合, 湾口で分離して湾内へ入射する内部ケルビン波の一部が湾口を跳び越えることが明らかになるとともに, その振幅は湾口幅が狭くなるに従い大きくなることが判明した。Numerical experiments using a two-layer model with simple topography were performed to investigate the scattering of a coastal-trapped wave (CTW) generated by alongshore winds. In the case of a narrow shelf with a deep bay, an internal Kelvin-type wave propagated into the deep bay without wave separation and mode conversion. However, in the case of a narrow shelf with a shallow bay, the internal Kelvin-type wave separated at the bay mouth into two types of waves, a shelf wave and an internal Kelvin wave. The shelf wave propagated along the shelf edge off the bay mouth, while the internal Kelvin wave propagated into the shallow bay. The sea level fluctuations along the southeast coast of Japan that were caused by typhoon 8818 were well explained by the separation and mode conversion process of CTW. In the case of a wide shelf with a shallow bay, a generated shelf wave was propagated along the shelf edge without separation at the bay mouth. In cases with a disconnection of shelf, the shelf wave was found to bridge over the disconnection of shelf and the amplitude of the bridged wave decreased exponentially with increasing disconnection length. Most of the internal Kelvin-type wave bridged over the bay mouth when the width of the bay mouth was shorter than twice the internal radius of deformation.

Journal

  • Oceanography in Japan

    Oceanography in Japan 14(3), 441-458, 2005-05-05

    日本海洋学会

References:  17

Cited by:  4

Codes

  • NII Article ID (NAID)
    110003375620
  • NII NACSIS-CAT ID (NCID)
    AN10382760
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    09168362
  • NDL Article ID
    7352716
  • NDL Source Classification
    ZM44(科学技術--地球科学--海洋・陸水・火山)
  • NDL Call No.
    Z15-778
  • Data Source
    CJP  CJPref  NDL  NII-ELS 
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