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Ikeda, Motoyoshi; Suzuki, Fumiyuki; Oba, Tadamichi

doi:10.1023/a:1007831122343

Cited by 29 publications

(8 citation statements)

References 12 publications

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“…[4] Box models have been used in the study of paleoceanography before [e.g., Ikeda et al, 1999;Rohling, 1999;Matthiesen and Haines, 2003;Meijer, 2006]. This is, however, the first time that a box model has been used to study the circulation of the Tethys and its evolution during closure of the eastern gateway.…”

Section: Introductionmentioning

confidence: 99%

An oceanic box model of the Miocene Mediterranean Sea with emphasis on the effects of closure of the eastern gateway

et al. 2009

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[1] The early Miocene Mediterranean Sea had two gateways toward the open ocean: the Indian Ocean in the east and the Atlantic Ocean in the west. Closure of the eastern connection during the middle Miocene had important effects on the water properties and circulation of the Mediterranean Sea. To gain insight into the circulation of the Mediterranean Sea during the Miocene and the effects of closure, we apply a box model. The model has three boxes representing the Atlantic Ocean, the Mediterranean Sea, and the Indian Ocean. The boxes exchange water, heat, and salt through surface and deep flow. The deep flow is driven by the density contrast between the boxes. We analyze the variation of (1) temperature, salinity, and residence time and (2) magnitude and configuration of the gateway flows in response to changes in the gateways and in atmospheric forcing (freshwater and heat fluxes). The analysis is presented in three parts: preclosure, closure, and postclosure. Model results are compared with observations reported in literature. The model analysis indicates that (1) prior to closure of the eastern gateway, deep flow was most likely west to east in both gateways provided the density of the Indian Ocean was relatively low, (2) the preclosure system was not very sensitive to freshwater and heat flux, (3) the response of the Mediterranean water properties and flow to gradual closure is nonlinear, (4) closure probably resulted in cooling and a rise of salinity and residence time of the Mediterranean Sea if evaporation exceeded freshwater input, and (5) multiple equilibrium states are possible (i.e., different surface and deep flow for the same value of freshwater flux) in the case of two gateways. In addition, we tentatively propose a best-fit scenario for the history of closure, linking the available data and our model results.

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Section: Introductionmentioning

confidence: 99%

An oceanic box model of the Miocene Mediterranean Sea with emphasis on the effects of closure of the eastern gateway

et al. 2009

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“…Our data imply that the upper ocean stratification of the JS began to quickly collapse when the sea level rose above −90 m, opening and connecting the basin to the adjacent seas again (Keigwin & Gorbarenko, 1992;Oba et al, 1991). As a result, relatively saline water flowed into the JS through the Tsugaru Strait (Ikeda et al, 1999;Isobe, 2020;Oba et al, 1991) and/or Tsushima Strait (Domitsu & Oda, 2006;Keigwin & Gorbarenko, 1992). Increased salinity and strengthened convection resulted in the significant increase in planktic foraminiferal δ 18 O values (Figure 2c) and the alkenone content ( Figure S2b).…”

Section: Deglacial Transition Stage (163-137 Ka Bp)mentioning

confidence: 76%

Evolution of the Upper Ocean Stratification in the Japan Sea Since the Last Glacial

Shi

Gong

et al. 2020

Geophysical Research Letters

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Paleoceanographic evidence commonly indicates that Last Glacial Maximum surface temperatures in the Japan Sea were comparable to modern conditions, in striking difference to colder neighboring regions. Here, based on a core from the central Japan Sea, our results show similar UK′37‐ and TEXL86‐derived temperatures between 24.7 and 16.3 ka BP, followed by an abrupt divergence at ~16.3 ka BP and a weakening of divergence after ~8.7 ka BP. We attribute this process to a highly stratified glacial upper ocean controlled by the East Asian Summer Monsoon, increasing thermal gradient between surface and subsurface layers during the deglaciation and the intrusion of Tsushima Warm Current since the mid‐Holocene, respectively. Therefore, we suggest that threshold‐like changes in upper‐ocean temperatures linked to sea level rise and monsoon dynamics, rather than just sea surface temperatures, play a critical role in shaping the thermal and ventilation history of this NW Pacific marginal sea.

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“…Ikeda et al (1999) simply specified an idealistic Q evolution (linearly decreased from 1.0 to 0.01 Sv between 25 and 17 kyr BP, remained at 0.01 Sv over 17-15 kyr BP, linearly increased to 1.5 Sv from 15 to 10 kyr BP and remained at 1.5 Sv until present day). An idealistic P-E evolution was also specified and remained as a time-independent constant (0.3 m y −1 ≈ 0.82 mm d −1 ) both in Matsui et al (1998) and Ikeda et al (1999). Apparently, the Q and P-E evolutions used in the above studies are not supported by paleoceanographic evidence nor do they have dynamical constraints, and therefore more careful examinations and refinements for a reasonable S JP reconstruction are needed.…”

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confidence: 99%

“…In this study, we also design a box model to reconstruct the S JP evolution over the past 35 kyr with a focus on the low S JP event at the LGM. As an improvement over Matsui et al (1998) and Ikeda et al (1999), we refine the Q and P-E evolutions to obtain a more precise value and timing for minimum S JP . For the Q evolution, we will first quantify the relationship between Q and sea level through a basin-scale realistic hydrodynamic model.…”

mentioning

confidence: 99%

“…They obtained a minimum S JP of 20 during 20-15 kyr BP. Similarly, Ikeda et al (1999) employed two boxes to represent the northern and southern parts of the upper 300 m in the Japan Sea, and estimated that the S JP in the two boxes reached their minimum values (28.83, 29.59) during 17-15 kyr BP. Despite the minimum S JP (value and timing) differences, the box model provides an alternative and feasible method to quantify low-salinity event.…”

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confidence: 99%

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Low Sea Surface Salinity Event of the Japan Sea During the Last Glacial Maximum

Zheng

Guo

Yang

et al. 2023

Paleoceanog and Paleoclimatol

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Abnormal lightening of the oxygen isotope ratio (δ18O) of planktonic foraminifera during the Last Glacial Maximum (LGM, ∼21 kyr BP) suggests that the Japan Sea had experienced a low sea surface salinity event at that time. However, the exact value and timing of minimum salinity have been controversial so far. To address this issue, we adopt a simple box model and reconstruct the sea surface salinity in the Japan Sea (SJP) over the past 35 kyr with a focus on the LGM period. In particular, as input data for the box model, the inflow transport through the Tsushima Strait (Q) is converted from sea level evolution using a newly defined relationship, in which Q reduces non‐linearly with the sea level reduction through a dynamically‐constrained realistic ocean model. Meanwhile, another input data of the box model, sea surface freshwater flux (precipitation minus evaporation (P‐E) evolution), is obtained by averaging multi‐paleoclimate models (PMIP3 and MIROC4m models) results. The reconstructed SJP using the box model reached its minimum value (20.2) at 20 kyr BP with a high coefficient of determination (R2) for δ18O (0.81, p << 0.01). Further analysis demonstrates that the above non‐linear relationship, determined by h3/2 (h is the strait depth), promises a more reasonable reconstruction of the SJP evolution. It is also concluded that both the value and timing of the minimum SJP depend on the Q evolution, and the P‐E evolution can modify the former. Therefore, the combination of Q and P‐E determines the exact value and timing of minimum salinity.

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Cited by 29 publications

References 12 publications

An oceanic box model of the Miocene Mediterranean Sea with emphasis on the effects of closure of the eastern gateway

An oceanic box model of the Miocene Mediterranean Sea with emphasis on the effects of closure of the eastern gateway

Evolution of the Upper Ocean Stratification in the Japan Sea Since the Last Glacial

Low Sea Surface Salinity Event of the Japan Sea During the Last Glacial Maximum

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