Effects of wave-current interactions on bay-shelf exchange

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  • 1 Key Laboratory of Physical Oceanography, Ministry of Education, at Ocean University of China, and Pilot National Laboratory for Marine Science and Technology, Qingdao, China
  • 2 College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao, China
  • 3 Shenzhen International Graduate School, Tsinghua University, Shenzhen, China
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Abstract

Bay-shelf exchange is critical to coastal systems as it promotes self-purification or pollution dilution of the systems. In this study, the effects of wave-current interactions on bay-shelf exchange are explored in a micromesotidal system – Daya Bay in southern China. Waves can enlarge the shear-induced seaward transport and reduce the residual-current-induced landward transport, which benefits the bay-shelf exchange; however, tides work oppositely and slow the wave-induced bay-shelf exchange due to vertical mixing and reduced shear-induced exchange. Five wave-current interactions are compared and it is found that the depth-dependent wave radiation stress (WRS) contributes most to the bay-shelf exchange, followed by the wave dissipation as a source term in the turbulence kinetic energy equation, and the mean current advection and refraction of wave energy (CARWE). The vertical transfer of wave-generated pressure to the mean momentum equation (also known as the form drag), and the combined wave-current bottom stress (CWCBS) play minor roles in the bay-shelf exchange. The bay-shelf exchange is faster under southerly wind than that under northerly wind as the bay is facing southeast; the synoptic events like storms enhance the bay-shelf exchange. The CARWE terms are dominant in both seasonal and synoptic variations of the bay-shelf exchange as they can significantly change the distribution of significant wave height. The WRS changes the bay-shelf exchange mainly through altering the flow velocity, whereas the wave dissipation on turbulence alters the vertical mixing. The form drag and the CWCBS have little impact on the bay-shelf exchange as well as its seasonal and synoptic variations.

Denotes content that is immediately available upon publication as open access.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author, E-mail address: songdh@ouc.edu.cn;

Abstract

Bay-shelf exchange is critical to coastal systems as it promotes self-purification or pollution dilution of the systems. In this study, the effects of wave-current interactions on bay-shelf exchange are explored in a micromesotidal system – Daya Bay in southern China. Waves can enlarge the shear-induced seaward transport and reduce the residual-current-induced landward transport, which benefits the bay-shelf exchange; however, tides work oppositely and slow the wave-induced bay-shelf exchange due to vertical mixing and reduced shear-induced exchange. Five wave-current interactions are compared and it is found that the depth-dependent wave radiation stress (WRS) contributes most to the bay-shelf exchange, followed by the wave dissipation as a source term in the turbulence kinetic energy equation, and the mean current advection and refraction of wave energy (CARWE). The vertical transfer of wave-generated pressure to the mean momentum equation (also known as the form drag), and the combined wave-current bottom stress (CWCBS) play minor roles in the bay-shelf exchange. The bay-shelf exchange is faster under southerly wind than that under northerly wind as the bay is facing southeast; the synoptic events like storms enhance the bay-shelf exchange. The CARWE terms are dominant in both seasonal and synoptic variations of the bay-shelf exchange as they can significantly change the distribution of significant wave height. The WRS changes the bay-shelf exchange mainly through altering the flow velocity, whereas the wave dissipation on turbulence alters the vertical mixing. The form drag and the CWCBS have little impact on the bay-shelf exchange as well as its seasonal and synoptic variations.

Denotes content that is immediately available upon publication as open access.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author, E-mail address: songdh@ouc.edu.cn;
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