Role of the deep North Pacific in overturning circulation and carbon cycling

2020 ◽  
Author(s):  
Weng-Si Chao ◽  
Lara Jacobi ◽  
Lester Lembke-Jene ◽  
Ralf Tiedemann ◽  
Dirk Nürnberg
Keyword(s):  
Deep Water ◽  
North Pacific ◽  
Global Climate ◽  
Sediment Cores ◽  
Nutrient Concentrations ◽  
Northwest Pacific ◽  
Biological Productivity ◽  
Carbon And Oxygen Isotopes ◽  
Close Link ◽  
The North

<p>At present, the North Pacific constitutes one of the main marine natural carbon sinks and thus helps regulate atmospheric CO<sub>2 </sub>concentrations. Understanding past changes in North Pacific deep water circulation and biological productivity are of particular importance, since the region likely changed these characteristics on both orbital and millennial time scales, and may have even undergone switches between being a carbon source and sink. We present a suite of new sediment records retrieved from the subarctic Northwest Pacific along the Emperor Seamount Chain in order to contribute to the Pleistocene stratigraphy and reconstruct changes in the physical and biological carbon pump on millennial to orbital timescales. We used high-resolution AMS 14C-derived benthic-planktic (B-P) foraminiferal ventilation ages, and stable carbon and oxygen isotopes of epibenthic foraminifera along both meridional and water depth transects in order to establish deep water ventilation patterns and reconstruct nutrient concentrations over the last 200 ka. We used X-ray fluorescence (XRF)-scanning records combined with radiocarbon dating to correlate prominent patterns between sediment cores, and to develop a stratigraphic framework for the study area. We used changes in Ba/Ti, Ca/Ti, Si/Ti ratios to assess variationsin biological productivity. Biogenic Barium (Ba/Ti) and Calcium (Ca/Ti) ratios generally show high values during interglacials and low values during glacials. This pattern resembles subpolar Northwest Pacific ODP Site 882, which shows a good correlation to the global CO<sub>2 </sub>record. These results provide evidence for the close link between global climate, the ocean carbon cycle and marine biogeochemistry in North Pacific.</p>

Was deep water formed in the North Pacific during the Late Quaternary? Cadmium evidence from the Northwest Pacific

1994 ◽  
Vol 124 (1-4) ◽  
pp. 185-194 ◽  
Author(s):  
N. Ohkouchi ◽  
H. Kawahata ◽  
M. Murayama ◽  
M. Okada ◽  
T. Nakamura ◽  
...  
Keyword(s):  
Deep Water ◽  
North Pacific ◽  
Late Quaternary ◽  
Northwest Pacific ◽  
The North ◽  
The North Pacific

Deep‐Water Formation in the North Pacific During the Late Miocene Global Cooling

2021 ◽  
Vol 36 (2) ◽  
Author(s):  
Lina Zhai ◽  
Shiming Wan ◽  
Christophe Colin ◽  
Debo Zhao ◽  
Yuntao Ye ◽  
...  
Keyword(s):  
Deep Water ◽  
Late Miocene ◽  
North Pacific ◽  
Deep Water Formation ◽  
The North ◽  
Global Cooling ◽  
Water Formation ◽  
The North Pacific

scholarly journals Strengthened Relationship between Tropical West Pacific and Midsummer Precipitation over Northeast China after the Mid-1990s

2020 ◽  
Vol 33 (16) ◽  
pp. 6833-6848
Author(s):  
Tingting Han ◽  
Minghua Zhang ◽  
Botao Zhou ◽  
Xin Hao ◽  
Shangfeng Li
Keyword(s):  
North Pacific ◽  
Northeast China ◽  
Aleutian Islands ◽  
Northwest Pacific ◽  
West Pacific ◽  
The North ◽  
Circulation Anomalies ◽  
The Relationship ◽  
The North Pacific ◽  
Central North Pacific

AbstractThe relationship between the tropical west Pacific (TWP) and East Asian summer monsoon/precipitation has been documented in previous studies. However, the stability for the signals of midsummer precipitation in the TWP sea surface temperature (SST_TWP), which is important for climate variation, has drawn little attention. This study identifies a strengthened relationship between the leading empirical orthogonal function mode (EOF1) of midsummer precipitation over Northeast China (NEC) and the SST_TWP after the mid-1990s. The EOF1 mode shows a significant positive correlation with the SST_TWP for 1996–2016, whereas the relationship is statistically insignificant for 1961–90. Further results indicate that the North Pacific multidecadal oscillation (NPMO) shifts to a positive phase after the 1990s. In the positive NPMO phase, the anomalous circulation over the northeast Pacific expands westward over the central North Pacific–Aleutian Islands region. Concurrently, the SST_TWP-associated wavelike pattern propagates northeastward from the west Pacific to the northwest Pacific and farther to the North Pacific, facilitating the poleward expansion and intensification of the SST_TWP-related circulation anomalies over the North Pacific. Therefore, the SST_TWP has an enhanced influence on NEC precipitation through the modulation of the circulation anomalies over the central North Pacific–Aleutian Islands region after the mid-1990s. Additionally, the tropical anticyclone/cyclone associated with the SST_TWP expands westward to South China, exerting an intensified impact on meridional wind anomalies along eastern China and on moisture transport over NEC. These conditions jointly contribute to the strengthened relationship between the SST_TWP and the EOF1 mode of NEC midsummer precipitation after the mid-1990s.

scholarly journals The pliocene record of climatic change: equator-to-pole biotic response

1992 ◽  
Vol 6 ◽  
pp. 78-78
Author(s):  
Thomas M. Cronin ◽  
H.J. Dowsett
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
North Pacific ◽  
Global Climate ◽  
North Pacific Ocean ◽  
Thermal Gradients ◽  
High Latitudes ◽  
Near Surface ◽  
Temperature Changes ◽  
The North

Pliocene faunal events in tropical and subtropical regions of the Americas and the Caribbean have been causally linked to global climatic events, particularly, progressive cooling and increased amplitude of climatic cycles between 3.5 and 2.0 Ma. However, the rate and magnitude of Pliocene temperature changes has been determined in only a few climate proxy records. Our study contrasts paleoceanographic conditions at 3 Ma, an extremely warm period in many areas, with conditions 2.4 Ma, a much cooler interval, in equator-to-pole transects for the North Atlantic and the North Pacific Oceans. By using microfaunal data (ostracodes from ocean margin environments and planktic foraminifers from deep sea cores), quantitative factor analytic and modern analog dissimilarity coefficient analyses were carried out on faunas from the following sections.Our studies lead to the following conclusions: (1) Equator-to-pole thermal gradients in the oceans at 3.0 Ma were not as steep as they are today, but thermal gradients at 2.4 Ma were steeper than those today; (2)At 3 Ma middle to high latitudes were substantially warmer than today, but tropical regions were about the same; (3)Substantial cooling occurred in middle and high latitudes in the western North Pacific Ocean and the western North Atlantic between 3 Ma and 2.4 Ma; (4)Ocean water temperatures off the southeastern U.S. remained the same or cooled only slightly between 3 Ma and 2.4 Ma. Our results support the hypothesis that ocean circulation changes, probably resulting from the closure of near surface water by the Isthmus of Panama, had significant impact on equator-to-pole heat transport and global climate between about 3 and 2.4 Ma. They also argue against the hypothesis that climatically induced ocean temperature changes were directly linked to a major marine extinction in the southwestern North Atlantic and Caribbean.

scholarly journals The role of Northeast Pacific meltwater events in deglacial climate change

2020 ◽  
Vol 6 (9) ◽  
pp. eaay2915 ◽  
Author(s):  
Summer K. Praetorius ◽  
Alan Condron ◽  
Alan C. Mix ◽  
Maureen H. Walczak ◽  
Jennifer L. McKay ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
North Pacific ◽  
Sediment Cores ◽  
Younger Dryas ◽  
Columbia River ◽  
Sea Surface ◽  
Subsurface Water ◽  
Last Deglaciation ◽  
Northeast Pacific ◽  
The North

Columbia River megafloods occurred repeatedly during the last deglaciation, but the impacts of this fresh water on Pacific hydrography are largely unknown. To reconstruct changes in ocean circulation during this period, we used a numerical model to simulate the flow trajectory of Columbia River megafloods and compiled records of sea surface temperature, paleo-salinity, and deep-water radiocarbon from marine sediment cores in the Northeast Pacific. The North Pacific sea surface cooled and freshened during the early deglacial (19.0-16.5 ka) and Younger Dryas (12.9-11.7 ka) intervals, coincident with the appearance of subsurface water masses depleted in radiocarbon relative to the sea surface. We infer that Pacific meltwater fluxes contributed to net Northern Hemisphere cooling prior to North Atlantic Heinrich Events, and again during the Younger Dryas stadial. Abrupt warming in the Northeast Pacific similarly contributed to hemispheric warming during the Bølling and Holocene transitions. These findings underscore the importance of changes in North Pacific freshwater fluxes and circulation in deglacial climate events.

Palaeo-oceanography, margin stratigraphy and palaeophysiography of the Tertiary North Atlantic and Norwegian-Greenland seas

1980 ◽  
Vol 294 (1409) ◽  
pp. 177-185 ◽  
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Global Climate ◽  
Circulation Pattern ◽  
The Arctic ◽  
Continental Margins ◽  
Long Distance ◽  
Sea Level Fluctuations ◽  
The North ◽  
Border Zones

The Tertiary was a period of dramatic changes of the palaeo-oceanography of the world’s oceans in general and of the North Atlantic in particular. These changes were caused by (1) the bathymetric evolution of ocean basins and intrabasin pathways (opening of the Norwegian-Greenland Seas and of the pathway to the Arctic Ocean, interruption of the circumglobal equatorial seaway); (2) the geographical development of the oceans and adjacent marginal basins in the context of rapid and intensive eustatic sea level fluctuations; and (3) the deterioration of the global climate throughout the Tertiary (change from a non-glacial to a glacial world, causing major changes in circulation of the surface and deep water). A biostratigraphy of Tertiary sediments deposited close to the continental margins has been developed by using remains of planktonic floras and faunas. Their presence in these sediments and their usefulness for long distance correlations of margin sediments, depend upon the circulation pattern and hydrographic gradients of the oceanic surface and deep water masses, the climatic regime over the continental border zones, and the probability of their post-depositional preservation.

scholarly journals The global ocean circulation on a retrograde rotating earth

2011 ◽  
Vol 7 (2) ◽  
pp. 487-499 ◽  
Author(s):  
V. Kamphuis ◽  
S. E. Huisman ◽  
H. A. Dijkstra
Keyword(s):  
Ocean Circulation ◽  
Deep Water ◽  
North Pacific ◽  
Global Ocean ◽  
Freshwater Flux ◽  
Deep Water Formation ◽  
The North ◽  
Water Formation ◽  
Global Ocean Circulation ◽  
The North Pacific

Abstract. To understand the three-dimensional ocean circulation patterns that have occurred in past continental geometries, it is crucial to study the role of the present-day continental geometry and surface (wind stress and buoyancy) forcing on the present-day global ocean circulation. This circulation, often referred to as the Conveyor state, is characterised by an Atlantic Meridional Overturning Circulation (MOC) with a deep water formation at northern latitudes and the absence of such a deep water formation in the North Pacific. This MOC asymmetry is often attributed to the difference in surface freshwater flux: the Atlantic as a whole is a basin with net evaporation, while the Pacific receives net precipitation. This issue is revisited in this paper by considering the global ocean circulation on a retrograde rotating earth, computing an equilibrium state of the coupled atmosphere-ocean-land surface-sea ice model CCSM3. The Atlantic-Pacific asymmetry in surface freshwater flux is indeed reversed, but the ocean circulation pattern is not an Inverse Conveyor state (with deep water formation in the North Pacific) as there is relatively weak but intermittently strong deep water formation in the North Atlantic. Using a fully-implicit, global ocean-only model the stability properties of the Atlantic MOC on a retrograde rotating earth are also investigated, showing a similar regime of multiple equilibria as in the present-day case. These results indicate that the present-day asymmetry in surface freshwater flux is not the most important factor setting the Atlantic-Pacific salinity difference and, thereby, the asymmetry in the global MOC.

New insights into the latitudinal ventilation variations in the Japan Sea since the Last Glacial Maximum: A radiolarian assemblage perspective

2020 ◽  
Author(s):  
Zhi Dong ◽  
Xuefa Shi ◽  
Jianjun Zou ◽  
Yanguang Liu ◽  
Ruxi Dou ◽  
...  
Keyword(s):  
Deep Water ◽  
Coastal Upwelling ◽  
Sediment Cores ◽  
Japan Sea ◽  
Volume Transport ◽  
The North ◽  
Radiolarian Assemblage ◽  
Basin Scale ◽  
Japan Sea Proper Water ◽  
The Japan Sea

<p>The formation of intermediate and deep water plays a key role in regulating climate changes at a variety of time scales through the heat redistribution and carbon cycling. The Japan Sea has unique water-mass characteristics in the North Pacific with its own deep-water formation within the Sea itself called Japan Sea Proper Water (JSPW). Latitudinal ventilation changes in the Japan Sea were reconstructed using radiolarian assemblage from three sediment cores, extending from the southwestern, central to northwestern Japan Sea. Here, we present downcore faunal records spanning the last 25 ka as well as other existing ventilation records in the Japan Sea, and provide reliable evidence to evaluate the potential controlling mechanism that lead to onset and interruption of JSPW ventilation. Taking all together, we argue that radiolarian assemblage records have revealed a distinct basin-scale transition in deep-water conditions from anoxic to oxic during the deglaciation related to changing surface hydrography. However, it should be recognized that there is significant potential for bias in the timing of the ventilation changes among regions. Deep ventilation in the central Japan Sea has been in an interglacial mode during the Bølling/Allerød presumably related to northward volume transport of the Tsushima Warm Current. Moreover, the decrease of JSPW Assemblage at the B/A in southwestern Japan Sea was attributed to higher export productivity, facilitating suboxic deepwater condition through enhanced consumption of oxygen, which was probably caused by coastal upwelling. In contrast, the weakening ventilation of the northwestern Japan Sea during the B/A and YD periods was probably caused by the blocking effect of the sea ice. Note: This study was supported by the National Natural Science Foundation of China (Grant No. 41420104005, U1606401) and National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-04).</p>

Removing the North Pacific halocline: Effects on global climate, ocean circulation and the carbon cycle

2012 ◽  
Vol 61-64 ◽  
pp. 106-113 ◽  
Author(s):  
L. Menviel ◽  
A. Timmermann ◽  
O. Elison Timm ◽  
A. Mouchet ◽  
A. Abe-Ouchi ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Ocean Circulation ◽  
North Pacific ◽  
Global Climate ◽  
The North ◽  
The North Pacific
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