Formation mechanism of the cold-water belt formed off the soya warm current

Ishizu, Miho; Kitade, Yujiro; Matsuyama, Masaji

doi:10.1007/s10872-006-0068-0

Cited by 26 publications

(20 citation statements)

References 9 publications

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“…The current axis is present at this temperature transition zone with strong vertical and horizontal shear. The cold water offshore of the axis shows a doming structure and the thermocline water (;158C) outcrops to the surface at about 143.38E, consistent with observations (see, e.g., Ishizu et al 2006).…”

Section: Introductionsupporting

confidence: 89%

“…1a, see also Matsuyama et al 2006;Ishizu et al 2006, and references therein). The cold belt is apparently generated along the southwestern coast of Sakhalin Island upstream of the strait and extends southward along the SWC.…”

Section: Introductionmentioning

confidence: 97%

“…The cold belt is apparently generated along the southwestern coast of Sakhalin Island upstream of the strait and extends southward along the SWC. Further, a subsurface doming structure develops below the surface cold belt, as shown in Ishizu et al (2006). Therefore, subsurface cold water outcrops to form the surface cold belt.…”

Section: Introductionmentioning

confidence: 98%

“…As noted before, this is not generated merely by advection of the cold surface water from upstream, but by outcropping of cold water from below. Ishizu et al (2006) suggested that the cold water upwells due to the Ekman pumping from the bottom boundary layer associated with cyclonic vorticity between the nearshore strong current and offshore calm water. However, stratification over the sloping bottom may shut down Ekman pumping due to the thermal wind balance within a few days after spinup of the overlying current (Chapman 2002).…”

Section: Introductionmentioning

confidence: 99%

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Rotating Stratified Barotropic Flow over Topography: Mechanisms of the Cold Belt Formation off the Soya Warm Current along the Northeastern Coast of Hokkaido

Mitsudera

Uchimoto

Nakamura

2011

Journal of Physical Oceanography

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The Soya ''Warm Current'' (SWC) flows through a shallow strait between the Japan Sea and the Sea of Okhotsk. The SWC has a jet structure downstream of the strait along the northern coast of Hokkaido with a maximum speed exceeding 1 m s 21 at its axis in summer and fall. A surface cold belt with a subsurface doming structure forms offshore of the SWC axis. Mechanisms of the cold belt formation are discussed from a point of view of resonant interaction between a barotropic stratified flow and a shallow sill and subsequent baroclinic adjustment along the SWC. When a stratified current rides a slope upstream, the thermocline displaces upward greatly and outcrops owing to resonant generation of internal Kelvin waves if the upper layer is thinner than the lower layer. The control section, where a Froude number is unity, occurs ''upstream'' from the sill crest when the ambient inflow has a barotropic flow component. These upwelling features closely resemble those along the southwestern coast of Sakhalin Island. The SWC then flips from an upwelling-type to a downwelling-type structure; in doing so, it transits from the west coast of Sakhalin to the east coast of Hokkaido. It is this transition that leads to the offshore doming structure, which propagates downstream as a vorticity wave, manifesting the cold belt at the surface.

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Section: Introductionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Rotating Stratified Barotropic Flow over Topography: Mechanisms of the Cold Belt Formation off the Soya Warm Current along the Northeastern Coast of Hokkaido

Mitsudera

Uchimoto

Nakamura

2011

Journal of Physical Oceanography

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“…Thus, one of the reasons why A. tamarense was frequently found in oceanic ) of A. tamarense tended to be found near the frontal areas outside the SWC in the present study. It has been reported that the formation of a cold water belt through upwelling can often be detected in the frontal areas in summer (Nakata et al 1996, Ishizu et al 2006, and that diatom blooms frequently occur through utilization of the richer nutrients in the upwelling water (Watanabe 1990). In the present study, the blooms of A. tamarense existed not within the frontal area, but rather near the frontal area where the diatom blooms were also found (Figs.…”

mentioning

confidence: 99%

Spatial distribution of the toxic dinoflagellate Alexandrium tamarense in summer in the Okhotsk Sea off Hokkaido, Japan

Shimada¹,

Sawada²,

Kuribayashi³

et al. 2010

Plankton Benthos Res

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Abstract:To investigate the mechanisms influencing the spatial distribution of the toxic dinoflagellate Alexandrium tamarense in the Okhotsk Sea off Hokkaido, Japan, intensive field surveys were conducted at 34-37 stations in late July every year from in [2002][2003][2004][2005][2006][2007]. Alexandrium tamarense occurred every year. However, the abundance of A. tamarense fluctuated year by year, with extremely low cell densities of A. tamarense in 2005. High abundances of A. tamarense were found frequently in the oceanic area of the surface low-salinity water (LSW, salinityՅ32.5) and the mixed water (MW). Low abundances were found along the coastal area of the Soya Warm Current (SWC, salinityՆ33.6) and in the dichothermal water (DTW, temperatureՅ2°C) in the layer of oceanic areas deeper than 30 m. The PO 4 -P concentration in each water mass was in the order DTWϾMWϾLSWϾSWC and the lowest PO 4 -P concentration that occurred in the SWC is considered to be a potential limiting factor for the growth of A. tamarense. The reason for the low A. tamarense abundance in the DTW is considered to be the low water temperature and low light intensity. It is concluded that the water mass of LSW has favorable conditions for the growth of A. tamarense. The relative frequency of each water mass fluctuated every year and the results suggest that the frequency of occurrence of the LSW and MW is one of the most significant factors controlling the abundance of A. tamarense in the area.

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