Renewal of the bottom water after the winter 2000–2001 may spin‐up the thermohaline circulation in the Japan Sea

Senjyu, Tomoharu; Aramaki, Takafumi; Otosaka, Shigeyoshi; Togawa, Orihiko; Danchenkov, Mikhail; Karasev, E. V.; Volkov, Yuri N.

doi:10.1029/2001gl014093

Cited by 77 publications

(52 citation statements)

References 14 publications

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“…This event was identified from water column anomalies of chemical tracers (dissolved oxygen, nutrients, and chlorofluorocarbons) just above the seafloor in the coastal zone off Vladivostok in the summer of 2001 (Kim et al, 2002;Senjyu et al, 2002;Talley et al, 2003;Tsunogai et al, 2003). By using moored current meters, Senjyu et al (2002) observed strong bottom currents up to 8 cm s −1 from mid-February 2001, suggesting a spin-up of the thermohaline circulation in the Japan Sea. These physicochemical observations demonstrated that the abyssal circulation pattern (conveyor belt) of the Japan Sea could shift immediately as a response to major changes in climate and weather conditions.…”

Section: Temporal Change Of the Japan Sea Bottom Watermentioning

confidence: 99%

The Sea of Japan and Its Unique Chemistry Revealed by Time-Series Observations over the Last 30 Years

Gamo¹,

Nakayama²,

Takahata³

et al. 2014

Monogr. Environ. Earth Planets

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Chemical tracers in seawater, as well as physical parameters such as temperature and salinity, have been measured to better characterize the dynamics of water convection and its spatiotemporal changes in the Sea of Japan (also called the Japan Sea), a semi-closed, hyperoxic marginal sea (maximum depth: ∼3,800 m) in the northwestern corner of the Pacific Ocean. Repeated conductivity, temperature, and depth (CTD) observations and measurements of dissolved oxygen, for more than 30 years, have confirmed that the bottom layer of the Japan Sea, with a thickness of ∼1 km below the boundary at a depth of ∼2,500 m, is characterized by vertical homogeneity with fluctuations of potential temperature and dissolved oxygen of <0.001• C and <0.5 µmol kg −1 , respectively. The timescale of the abyssal circulation in the Japan Sea has been estimated to be 100-300 years, using 14 C and other chemical tracers. Stable isotope analyses for dissolved He, O 2 and CH 4 have given us information on their unique geochemical cycles in the Japan Sea. Profiles of the short-lived radioisotope 222 Rn just above the sea bottom have brought new insights into the short-term lateral water movement with a timescale of several days in the Japan Sea bottom water. It is of special concern that the gradual deoxygenation and warming of the bottom water over the last 30 years have resulted in an ∼10% decrease in dissolved oxygen and ∼0.04• C increase in potential temperature, suggesting a change of the deep convection system in the Japan Sea. The temporal changes in the vertical profiles of tritium from 1984 to 1998 have suggested a shift of the abyssal circulation pattern from a "total (overall) convection mode" to a "shallow (partial) convection mode". It is likely that the global warming since the last century has hindered the formation of dense surface seawater and its ability to sink down to the bottom, isolating the bottom layer from the deep convection loop that is indispensable as the source of cold and oxygen-rich water. However, the decreasing trend of bottom dissolved oxygen between 1977 and 2010 was not monotonous; rather, it was interrupted by an occasional break in the winter of 2000-2001, when severely cold weather may have resulted in especially dense surface water to sink down to the bottom layer for its ventilation.

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Section: Temporal Change Of the Japan Sea Bottom Watermentioning

confidence: 99%

The Sea of Japan and Its Unique Chemistry Revealed by Time-Series Observations over the Last 30 Years

Gamo¹,

Nakayama²,

Takahata³

et al. 2014

Monogr. Environ. Earth Planets

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“…/NÞÞ of warm updrafts at 0:1z i and 0:2z i among our case (Jsea), GALE case (Chou and Zimmerman 1989), and AMTEX case (Mahrt and Paumier 1984 Senjyu et al (2002) and Tsunogai et al (2003).…”

Section: Comparison With Other Oceansmentioning

confidence: 99%

“…Cold, saline water (Japan Sea Proper Water, JSPW) is produced there by intense cooling and evaporation at the sea surface. Brine ejection, associated with sea-ice formation off Vladivostok, also facilitates JSPW formation (Senjyu et al 2002;Tsunogai et al 2003). Aircraft observations upstream of this region, will help to define surface turbulent heat fluxes during cold-air outbreaks, furthering the understanding of air-sea interactions in the Sea of Japan.…”

Section: Introductionmentioning

confidence: 99%

Aircraft Observations of Air-Mass Modification Upstream of the Sea of Japan during Cold-Air Outbreaks

Inoue

Kawashima

Fujiyoshi

et al. 2005

Journal of the Meteorological Society of Japan

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Russian research aircraft observed the atmospheric boundary layer in 2001 during weak (29 Jan.), intense (2 Feb.), and very intense (3 Feb.) cold air outbreaks. These observations occurred during a field experiment of Winter Meso-scale convective systems Observations, over the Sea of Japan in 2001 (WMO-01). Conditional sampling techniques were used to elucidate air-mass modification processes upstream of the Sea of Japan during cold-air outbreaks. Buoyancy fluxes in the lower boundary layer near the sea surface differed significantly among the three cases. TKE budgets suggest that the differences were characterized mainly by differences in buoyancy production. However, common properties in heat transfer did exist, namely intensity (3.0) and fractional coverage (28%) of rising thermals ðw þ T þ v Þ. Scale analysis showed that heating by convective-scale motions dominated in the lower boundary layer. Heating by meso-g scale motions became more important in the upper boundary layer. Near the cloud top, on the other hand, contributions by cold downdrafts ðw À T À v Þ to the total buoyancy flux ðw 0 T 0 v Þ dominated. The cloud-top w 0 T 0 v was about half of that near the sea surface, suggesting that cooling processes near the However, flux intensities in the present case, and in the GALE case, are stronger than in the AMTEX case. Impacts on ocean convection by the upstream, large surface heat fluxes are discussed.

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“…When applied to the East Sea, the model predicts along-slope currents over the bottom slope of order 10 cm/sec with a much larger peak in winter. It demonstrates that even a small amount of deep-water formation can generate significantly strong abyssal circulation in basins where geostrophic contours close on themselves, supporting the possibility that abyssal circulation is driven by unsteady sources in the East Sea, as suggested by Senjyu et al (2002). It is noted that this model addresses only the basin-scale qualitative feature of real situations, and cannot resolve other detailed features, such as the abnormally strong current over the flat bottom and various eddy-like or fluctuating currents observed in the Japan Basin (Takematsu et al 1999).…”

Section: Discussionmentioning

confidence: 55%

“…In fact, the model is idealized and gives only qualitative features of real situations. Nevertheless, it demonstrates that even small amounts of deep-water formation can generate significantly strong abyssal circulation in basins where geostrophic contours close on themselves, supporting the possibility that abyssal circulation can be driven by unsteady sources in the East Sea, as suggested by Senjyu et al (2002).…”

Section: Applicability To the East Seamentioning

confidence: 94%

Abyssal Circulation Driven by a Periodic Impulsive Source in a Small Basin with Steep Bottom Slope with Implications to the East Sea

Seung¹

2012

Ocean and Polar Research

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: In the theory of source-driven abyssal circulation, the forcing is usually assumed to be steady source (deep-water formation). In many cases, however, the deep-water formation occurs instantaneously and it is not clear whether the theory can be applied well in this case. An attempt is made to resolve this problem by using a simple reduced gravity model. The model basin has large depth change compared for its size, like the East Sea, such that isobaths nearly coincide with geostrophic contours. Deep-water is formed every year impulsively and flows into the model basin through the boundary. It is found that the circulation driven by the impulsive source is generally the same as that driven by a steady source except that the former has a seasonal fluctuation associated with unsteadiness of forcing. The magnitudes of both the annual average and seasonal fluctuations increase with the rate of deep-water formation. The problem can be approximated to that of linear diffusion of momentum with boundary flux, which well demonstrates the essential feature of abyssal circulation spun-up by periodic impulsive source. Although the model greatly idealizes the real situation, it suggests that abyssal circulation can be driven by a periodic impulsive source in the East Sea.

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Renewal of the bottom water after the winter 2000–2001 may spin‐up the thermohaline circulation in the Japan Sea

Cited by 77 publications

References 14 publications

The Sea of Japan and Its Unique Chemistry Revealed by Time-Series Observations over the Last 30 Years

The Sea of Japan and Its Unique Chemistry Revealed by Time-Series Observations over the Last 30 Years

Aircraft Observations of Air-Mass Modification Upstream of the Sea of Japan during Cold-Air Outbreaks

Abyssal Circulation Driven by a Periodic Impulsive Source in a Small Basin with Steep Bottom Slope with Implications to the East Sea

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