Short-term fluctuations south of Japan and their relationship with the Kuroshio path: 8- to 36-day fluctuations

Miyama, Toru; Miyazawa, Yasumasa

doi:10.1007/s10236-014-0701-1

Cited by 12 publications

(12 citation statements)

References 46 publications

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“…The residual current and the volume transport in the SIS vary with time due to the temporal variability of Kuroshio (e.g., Kawabe, ; Miyama & Miyazawa, ). In the SIS, it is difficult to make long‐term and/or operational observations of the current velocity using moorings equipped with current meters or acoustic Doppler current profilers (ADCPs), although they are the widely accepted methods to measure the time variation of the current at a particular location.…”

Section: Introductionmentioning

confidence: 99%

Variation of Residual Current in the Seto Inland Sea Driven by Sea Level Difference Between the Bungo and Kii Channels

et al. 2018

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Understanding residual (i.e., total minus tidal) currents in coastal seas is important because the residual currents affect long‐term material transports. In the Seto Inland Sea, Japan (SIS), a Bungo Channel to Kii Channel sea level difference causes a horizontal pressure gradient in the SIS and thus affects the residual current in the SIS. This study applies a linear regression method to examine how the residual current responds to the Bungo‐Kii sea level difference. The residual current is obtained using the reciprocal acoustic transmission data collected in the eastern portion of the Aki‐Nada sea area in 2012. The residual currents are estimated in the following three periods: from 12 April to 9 June, from 15 June to 21 July, and from 20 September to 27 October. In the regression analysis, an additional term is included to account for the fortnightly variation of the tide‐induced residual current. More than 75% of the observed residual currents can be explained by the sea level difference and the fortnightly variation. For the three periods, the variations of the residual current along the acoustic transmission line are, respectively, 0.20 ± 0.01, 0.22 ± 0.01, and 0.30 ± 0.01 cm s−1 per 1 cm of the Bungo‐Kii sea level difference. The corresponding variations in the volume transport are 920 ± 149, 1,040±170, and 1,390±223 m3 s−1 per 1 cm sea level difference. Comparing with the wind‐induced volume transport, we find that the sea level difference can cause a comparable volume transport variation.

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Section: Introductionmentioning

confidence: 99%

Variation of Residual Current in the Seto Inland Sea Driven by Sea Level Difference Between the Bungo and Kii Channels

et al. 2018

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“…The fluctuation first appears southeast of the Kii Peninsula and then propagates along the Kuroshio, resulting in a meander to the south of the Boso Peninsula. The generation and development of the fluctuation of the Kuroshio might be related to the mechanism proposed by Miyama and Miyazawa (2014), who suggest that short-term fluctuations of the Kuroshio downstream of Cape Shionomisaki are intensified due to topography-induced instability during the period of a nearshore Kuroshio path.…”

Section: Discussionmentioning

confidence: 87%

Unusually high sea level at the south coast of Japan in September 2011 induced by the Kuroshio

et al. 2020

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Using a coastal assimilation model, generation mechanism of unusually high sea level (UHSL) at the south coast of Japan in September 2011 is investigated. Both model results and tide gauge observations indicate that sea level rise associated with the UHSL event occurred twice in the middle and end of September. The first one, which is localized around the eastern part of the Seto Inland Sea, is caused by a cyclonic circulation in the Kii Channel formed as a result of northward migration of the Kuroshio axis toward Cape Shionomisaki. The second sea level rise, which is the main contributor to this UHSL event, is observed in wide areas not only at the south coast of Japan, but also at the coast of the Japan Sea. It is brought about by a coastal trapped wave (CTW) induced as a result of a fluctuation of the Kuroshio path to the south of the Boso Peninsula. The CTW with positive SSH anomalies propagates westward along the south coast of Japan, and then goes into the coast of the Japan Sea. Sensitivity experiments and a modal characteristic analysis indicate that the CTW is mainly characterized by the first mode baroclinic Kelvin wave. The phase speed for the first mode is calculated at 2.96 m s$$^{-1}$$ - 1 , which compares well with that estimated by tide gauge observations.

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“…anomalies u′ and v′ are the same as in equation 1, and the overbar in u ′ ρ ′ and v ′ ρ ′ represents time average on the seasonal time scale. BC represents the energy transfer from mean potential energy to EKE due to the baroclinic instability (Miyama & Miyazawa, 2014). Positive (negative) values of BC tend to increase (decrease) the EKE.…”

Section: 1029/2019gl086308mentioning

confidence: 99%

On the Role of the Kuroshio Extension Bimodality in Modulating the Surface Eddy Kinetic Energy Seasonal Variability

Wang

Pierini

2020

Geophysical Research Letters

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The modulation of the seasonal variability of the surface eddy kinetic energy (EKE) in the Kuroshio extension (KE) region induced by the stable and unstable KE states is analyzed using satellite‐based observations and high‐resolution ocean reanalysis data. The two KE states are found to strongly modulate the seasonal variability of the local surface EKE: the latter reaches its maximum in May–July if the KE is in its stable state, while it peaks in August–October if the KE is in its unstable state. Further investigation indicates that such behavior is mainly caused by the different baroclinic energy transfers induced by the meridional density gradients associated with the two KE states.

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Short-term fluctuations south of Japan and their relationship with the Kuroshio path: 8- to 36-day fluctuations

Cited by 12 publications

References 46 publications

Variation of Residual Current in the Seto Inland Sea Driven by Sea Level Difference Between the Bungo and Kii Channels

Variation of Residual Current in the Seto Inland Sea Driven by Sea Level Difference Between the Bungo and Kii Channels

Unusually high sea level at the south coast of Japan in September 2011 induced by the Kuroshio

On the Role of the Kuroshio Extension Bimodality in Modulating the Surface Eddy Kinetic Energy Seasonal Variability

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