Variability of the Kuroshio Current south of Sagami Bay as observed using long-range coastal HF radars
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Authors
Ramp, Steven R.
Barrick, Donald E.
Ito, Tomotaka
Cook, Michael S.
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Advisors
Date of Issue
2008
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Abstract
Ocean surface currents between Cape Nojima and Hachijo Island have been
mapped since fall 2000 using a pair of SeaSonde long-range HF radars. During September
2000 through December 2001, the no large meander (NLM) nearshore (n) and offshore
(o) modes were observed. The surface current maps allowed new details to be
observed in the structure of these modes and the transitions between them. Two
noteworthy phenomena include blocking of the surface currents when the Kuroshio was in
an extreme nearshore position behind the Zenisu Ridge and the ‘‘Kyucho’’ pattern
when the current retroflexed from the NLMo position. In early 2004, a large meander
(LM) developed and was well established in its historical position south of Honshu by
August 2004. Subsequently, the LM continued propagating downstream, but stopped
when it encountered the Izu Ridge. It then moved back to its original position near
137.5 E, and the process repeated itself. This east-west oscillation resulted in two
common positions for the LM south of Sagami Bay: from its more westerly position
(LMw, for west) the Kuroshio had a very favorable approach to the deep gap between
Miyake Island and the Zenisu Ridge, and the currents were strongly toward the northeast
through the region. When the meander moved up against the ridge (LMe, for east), a
strong along-ridge current toward the northwest was evident, which turned sharply
northeast when it encountered the shallow Zenisu Ridge. The dominant timescale for this
within-mode variability was about 30 days.
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Article
Description
The article of record as published may be found at http://dx.doi.org/10.1029/2007JC004132
Series/Report No
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Oceanography
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Citation
Ramp, S. R., D. E. Barrick, T. Ito, and M. S. Cook (2008), Variability of the Kuroshio Current south of Sagami Bay as
observed using long-range coastal HF radars, J. Geophys. Res., 113, C06024, doi:10.1029/2007JC004132.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.