Sea level response to wind field fluctuation around the tip of the Izu Peninsula |
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Authors: | Hirofumi Hinata Tetsuo Yanagi Chizuru Satoh |
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Institution: | (1) Coastal Zone System Division, Coastal and Marine Department, National Institute for Land and Infrastructure Management, Nagase, Yokosuka 239-0826, Japan;(2) Research Institute of Applied Mechanics, Kyushu University, Kasuga-Koen, Kasuga 816-8580, Japan;(3) Tokyo Kyuei Co., Ltd, Shiba, Kawaguchi 333-0866, Japan |
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Abstract: | The mechanism of a characteristic sea level response (barotropic coastal ocean response) to wind field fluctuation around
the tip of the Izu Peninsula observed during the middle of December 2000 to the middle of January 2001 was investigated based
on three types of numerical experiments using the Princeton Ocean Model with various parameters. The response was characterized
by the relaxation of sea level falling (rising) during eastward upwelling (westward downwelling) favorable wind regime. Analyses
of quasi-realistic numerical model results in terms of the vertically integrated momentum balances and vorticity balance for
the barotropic mode revealed that: 1) development/abatement of two anomalous circulations generated around the tip of the
Izu Peninsula controls the sea level response through the acceleration/deceleration of a quasi-geostrophic barotropic coastal
current between the circulations; 2) nonlinear vorticity advection by the Kuroshio Current and by the coastal current, coupled
with vorticity diffusion, decelerates the quasi-geostrophic coastal current in the latter half of the wind regimes, which
induces the relaxation of sea level rise/fall. The results of the quasi-realistic numerical experiment suggest that an analysis
of the vorticity balance for the barotropic mode contributes to a better understanding of sea level responses to wind in coastal
regions with strong currents and complex topography. In addition, a numerical experiment with idealized spatially uniform
density stratification and a quasi-realistic wind field shows that if the Kuroshio Current had been shifted far offshore from
the Izu Peninsula during the observation period, westward propagating continental shelf waves would have controlled the coastal
sea level response. |
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Keywords: | Sea level vorticity balance momentum balance Kuroshio Current Izu Peninsula |
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