Intermediate-water dynamics and ocean ventilation effects on the Indonesian Throughflow during the past 15,000 years: Ostracod evidence

Abstract. A detailed record of benthic foraminifera carbon isotopes from the South East Atlantic margin shows little glacial-interglacial variability between MIS-12 to MIS-10, suggesting that Glacial North Atlantic Intermediate Water (GNAIW) consistently penetrated to at least 30° S. Millennial-scale increases in either the mass or flux of GNAIW over the core site occur alongside reductions in Lower North Atlantic Deep Water recorded in North Atlantic sediment cores and show that the lower and intermediate limb of the Atlantic deepwater convective cell oscillated in anti-phase during previous glacial periods. In addition, a 500 yr resolution record of the Cape Basin intermediate-deep δ13C gradient shows that a reduction in deep Southern Ocean ventilation at the end of MIS-11 was consistent with a modelled CO2 drawdown of ~21–30 ppm. Further increases in the Southern Ocean chemical divide during the transition into MIS-10 were completed before minimum CO2 levels were reached, suggesting that other mechanisms such as alkalinity changes were responsible for the remaining ~45 ppm drawdown.

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Indirect estimation of turbulent mixing in western route of Indonesian throughflow

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/944/1/012059 ◽

2021 ◽

Vol 944 (1) ◽

pp. 012059

Author(s):

M Firdaus ◽

H Rahmawitri ◽

S Haryoadji ◽

A S Atmadipoera ◽

Y Suteja ◽

...

Keyword(s):

Turbulent Mixing ◽

Intermediate Water ◽

Indonesian Throughflow ◽

Pacific Water ◽

Dissipation Energy ◽

Tidal Waves ◽

Water Characteristics ◽

Vertical Diffusivity ◽

Water Origin ◽

Waves Interaction

Abstract The Indonesian Throughflow (ITF) via its western path conveys mainly North Pacific water origin with Smax thermocline water and Smin intermediate water from its entry portal in Sangihe-Talaud arcs to the main outflow straits in Lombok, Ombai and Timor passage. Along its route, the throughflow water characteristics transforms significantly due to strong diapycnal mixing forced by internal tidal waves interaction along complex topography such as passages, sill, straits, and shallow islands chains. This paper reports a brief estimate of turbulent mixing profiles in Sangihe chains, and Makassar Strait. The CTD dataset are obtained from the year of maritime continent (YMC) Cruise in August 2019 on board the R.V. Baruna Jaya I. The Thorpe method is used to analysis dissipation energy ( ε ) and vertical diffusivity (Kz ) from CTD dataset. It is shown that the highest ε epsilon 5.87 × 10−7 Wkg −1 and Kz 4.42 × 10−3 m2s 1 are found in the Sangihe area. In Labani Channel and Dewakang Sill the averaged vertical diffusivity is much weaker at the order of 10−4 m 2s1. Thus, Sangihe Chains station have the highest values compared to other stations at depth 950-1000 meters.

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Antarctic intermediate water circulation in the South Atlantic over the past 25,000 years

Paleoceanography ◽

10.1002/2016pa002975 ◽

2016 ◽

Vol 31 (10) ◽

pp. 1302-1314 ◽

Cited By ~ 18

Author(s):

Jacob N. W. Howe ◽

Alexander M. Piotrowski ◽

Delia W. Oppo ◽

Kuo-Fang Huang ◽

Stefan Mulitza ◽

...

Keyword(s):

South Atlantic ◽

Water Circulation ◽

Intermediate Water ◽

The South ◽

Antarctic Intermediate Water ◽

The Past

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Radiocarbon measurements on coexisting benthic and planktic foraminifera shells: potential for reconstructing ocean ventilation times over the past 20 000 years

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms ◽

10.1016/0168-583x(84)90538-x ◽

1984 ◽

Vol 5 (2) ◽

pp. 331-339 ◽

Cited By ~ 79

Author(s):

Wallace Broecker ◽

Alan Mix ◽

Michael Andree ◽

Hans Oeschger

Keyword(s):

Planktic Foraminifera ◽

The Past ◽

Ocean Ventilation

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Variability in the deep and intermediate water circulation of the Atlantic Ocean during the past 25,000 years: Northern Hemisphere modulation of the Southern Ocean

Deep Sea Research Part B Oceanographic Literature Review ◽

10.1016/0198-0254(88)92550-2 ◽

1988 ◽

Vol 35 (6) ◽

pp. 549

Keyword(s):

Atlantic Ocean ◽

Southern Ocean ◽

Northern Hemisphere ◽

Water Circulation ◽

Intermediate Water ◽

The Past

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Physiochemical Characteristics, Provenance, and Dynamics of Sand Dunes in the Arid Hexi Corridor

Frontiers in Earth Science ◽

10.3389/feart.2021.728202 ◽

2021 ◽

Vol 9 ◽

Author(s):

Bing-Qi Zhu ◽

Jia-Xing Zhang ◽

Chun Sun

Keyword(s):

Sand Dunes ◽

Hexi Corridor ◽

Water Dynamics ◽

Limiting Factor ◽

Formation Mechanisms ◽

Half Century ◽

The Past ◽

Aeolian Deposits ◽

Past Half Century ◽

Past Half

Dynamic changes of aeolian landforms under changing environments in a middle-latitude desert belt is a typical problem of climate change and related landscape response. It need a comprehensive understanding of the formation mechanisms of dune landforms with the supply of material suitable for aeolian transport and favorable conditions of sediment availability and wind regimes in the region. Based on comprehensive evidences from geomorphological, sedimentological, geochemical, and hydrological analysis, this study discussed the dynamical changes of different dune landforms during the past half century and their provenance in the Hexi Corridor, China. The results show that there are two states of sand dunes movement in the Hexi Corridor in the past half century, dynamic migration and basically stable. The crescent-shaped dunes move the fastest, followed by the chains of barchan dunes. Only the top of the pyramid dunes wigwags, while the parabolic dunes and the longitudinal dunes hardly move forward. The moving speed of sand dunes is positively correlated with the wind speed ≥5 m/s at a yearly scale. The grain size of sand dunes in the western Hexi Corridor is coarser than that in the central-eastern part, and also larger than those in other deserts of northern China and of the world. Different motion modes of saltation, suspension, and creeping are identified between aeolian, alluvial/fluvial and gobi sediments. Dune sands are mainly “sediments of in-situ rising” that originated from alluvial/fluvial/lacustrine deposits of ancient rivers, lakes, and aeolian deposits in the erosion zone of the forelands of the Qilian and Beishan Mountains and the north-neighboring deserts. This reveals a significance interaction between wind and water dynamics in the formation and evolution of aeolian landforms in the arid study area. Sufficient transport capacity is evidenced for both the western and eastern parts of the Hexi Corridor, sufficient sand supply and sand availability, however, is the favorable factor for dune formation in the east part but is the limiting factor for the west.

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Sea–ice and water dynamics and moonlight impact the acoustic backscatter diurnal signal over the eastern Beaufort Sea continental slope

10.5194/os-2020-48 ◽

2020 ◽

Cited By ~ 1

Author(s):

Igor A. Dmitrenko ◽

Vladislav Petrusevich ◽

Gérald Darnis ◽

Sergei A. Kirillov ◽

Alexander S. Komarov ◽

...

Keyword(s):

Sea Ice ◽

Continental Slope ◽

Light Transmission ◽

Acoustic Scattering ◽

Water Layer ◽

Beaufort Sea ◽

Water Dynamics ◽

Acoustic Backscatter ◽

Intermediate Water ◽

Upwelling And Downwelling

Abstract. A two-year-long time series of currents and acoustic backscatter from an Acoustic Doppler Current Profiler, moored over the eastern Beaufort Sea continental slope from October 2003 to September 2005, were used to assess dynamics and variability of the sound-scattering layer. It has been shown that acoustic backscatter is dominated by a synchronized diel vertical migration (DVM) of the zooplankton. Our results show that DVM timings (i) were synchronous with sunlight, and (ii) were modified by moonlight and sea-ice, which attenuates light transmission to the water column. Moreover, DVM is modified or completely disrupted during highly energetic current events. Thicker ice observed during winter 2004–2005 lowered the backscatter values, but favored extending DVM toward the midnight sun. In contrast to many previous studies, DVM occurred through the intermediate water layer during the ice-free season of the midnight sun in 2004. In 2005, the midnight sun DVM was likely masked by a high acoustic scattering generated by suspended particles. During full moon at low cloud cover, the nighttime moonlight illuminance led to zooplankton avoidance of the sub-surface layer disrupting DVM. Moreover, DVM was disrupted by upwelling, downwelling and eddy passing. We suggest that these deviations are consistent with DVM adjusting to avoid enhanced water dynamics. For upwelling and downwelling, zooplankton likely respond to the along-slope water dynamics dominated by surface- and depth-intensified flow, respectively. This drives zooplankton to adjust DVM by aggregating in the low or upper intermediate water layer for upwelling and downwelling, respectively. The baroclinic eddy reversed DVM below the eddy core.

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