Persistent millennial-scale links between North Pacific intermediate-water ventilation and North Atlantic Climate during the deglaciation and last glaciation

2020 ◽  
Author(s):  
Jianjun Zou ◽  
Xuefa Shi ◽  
Aimei Zhu ◽  
Yuan-Pin Chang ◽  
Min-Te Chen ◽  
...  
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Meridional Overturning Circulation ◽  
Intermediate Water ◽  
North Pacific Intermediate Water ◽  
The North ◽  
Last Glaciation ◽  
The North Pacific ◽  
Millennial Scale

<p>The deep ocean carbon cycle, especially carbon sequestration and outgassing, is one of the mechanisms to explain variations in atmospheric CO<sub>2</sub> concentrations on millennial and orbital timescales. However, the potential role of subtropical North Pacific subsurface waters in modulating atmospheric CO<sub>2</sub> levels on millennial timescales is poorly constrained. Here, we investigate a suite of geochemical proxies in a sediment core from the northern and middle Okinawa Trough to understand variations in intermediate-water ventilation of the subtropical North Pacific over the last 50,000 years (50 ka). Our results suggest that enhanced mid-depth western subtropical North Pacific (WSTNP) sedimentary oxygenation occurred during cold intervals during the last deglaciation and last glaciation, while oxygenation decreased during the Bölling-Alleröd (B/A) and warm interstadials. The enhanced oxygenation during cold spells is linked to the intensified North Pacific Intermediate Water (NPIW), while interglacial increase after 8.5 ka is linked to an intensification of the Kuroshio Current due to strengthened northeast trade winds over the tropics. The enhanced formation of NPIW during Heinrich Stadials was likely driven by the perturbation of sea ice formation and sea surface salinity oscillations in high-latitude North Pacific. The diminished sedimentary oxygenation during the B/A and interstadials due to decreased NPIW formation and enhanced export production, indicates an expansion of oxygen minimum zone in the North Pacific and enhanced CO<sub>2</sub> sequestration at mid-depth waters. We attribute the millennial-scale changes to intensified NPIW and enhanced abyss flushing during deglacial cold and warm intervals, respectively, closely related to variations in North Atlantic Deep Water formation. Out study extends the millennial-scale links between ventilation in the subtropical North Pacific Ocean and the Atlantic Climate into the last glaciations, highlighting the key roles of Atlantic Meridional Overturning Circulation in regulating the North Pacific environment at millennial timescales. Note: Financial support was provided by the National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-04) and by the National Natural Science Foundation of China (Grant Nos.: 41876065, 41476056, and U1606401).</p>

A modelling perspective of North Pacific Intermediate water in the future

2020 ◽  
Author(s):  
Xun Gong ◽  
Lars Ackermann ◽  
Gerrit Lohmann
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Carbon Sink ◽  
North Pacific Ocean ◽  
Intermediate Water ◽  
North Pacific Intermediate Water ◽  
The North ◽  
The Future ◽  
Near Future ◽  
The North Pacific

<p>North Pacific Intermediate water (NPIW) is a dominant water mass controlling ~400-1200m depth North Pacific Ocean, characterized by its low salinities and relatively lower temperatures. In the modern climate, the interplay between NPIW-related physical and biogeochemical processes among seasons determines annual-mean budget and efficiency of carbon sink into the North Pacific Ocean. Thus, to understand the NPIW physics is key to project roles of the North Pacific Ocean in changing Earth climate and carbon systems in the future. In this study, we provide a modelling view of the NPIW history since Yr 1850 (historical experiment) and its projection to near future (IPCC-defined RCP 4.2 and 8.5 experiments until Yr 2100), using new-generation Alfred Wegener Institute Earth System Model (AWI-ESM). Our results suggest an important role of regional hydroclimate feedback over the NW Pacific and Sea of Okhotsk in determining the NPIW from recent past to near future.</p>

scholarly journals Millennial-scale variations of sedimentary oxygenation in the western subtropical North Pacific and its links to the North Atlantic climate

2019 ◽  
Author(s):  
Jianjun Zou ◽  
Xuefa Shi ◽  
Aimei Zhu ◽  
Selvaraj Kandasamy ◽  
Xun Gong ◽  
...  
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
North Pacific ◽  
Co2 Concentration ◽  
Meridional Overturning Circulation ◽  
Atmospheric Co2 ◽  
Intermediate Water ◽  
The North ◽  
The North Atlantic ◽  
Millennial Scale

Abstract. Lower glacial atmospheric CO2 concentrations have been attributed to carbon sequestration in deep oceans. However, potential roles of voluminous subtropical North Pacific in modulating atmospheric CO2 levels on millennial timescale are poorly constrained. Further, an increase in respired CO2 concentration in the glacial deep ocean due to biological pump generally is coeval with less oxygenation in the subsurface layer. This link thus offers a chance to visit oceanic ventilation and the coeval export productivity based on redox-controlled sedimentary geochemical parameters. Here we investigate a suite of sediment geochemical proxies to understand the sedimentary oxygenation variations in the subtropical North Pacific (core CSH1) over the last 50 thousand years (ka). Our results suggest that sedimentary oxygenation at mid-depths of the subtropical North Pacific intensifies during the episodes of late glacial (50–25 ka), Last Glacial Maximum (LGM) and also the interval after 8.5 ka, especially pronounced for the North Atlantic millennial-scale abrupt cold events of the Younger Dryas, Heinrich Stadial (HS) 1 and 2. On the other hand, oxygen-depleted seawater is found during the Bölling-Alleröd (B/A) and Preboreal. Our findings of enhanced sedimentary oxygenation in the subtropical North Pacific is aligned with intensified formation of North Pacific Intermediate Water (NPIW) during cold spells, while the ameliorated sedimentary oxygenation seems to be linked with the intensified Kuroshio Current since 8.5 ka. In our results, diminished sedimentary oxygenation during the B/A indicates an enhanced CO2 sequestration at mid-depth waters, along with slight increase in atmospheric CO2 concentration. Mechanistically, we speculate that these millennial-scale changes were linked to the strength of North Atlantic Deep Water, leading to intensification of NPIW formation and enhanced abyss flushing during deglacial cold and warm intervals, respectively. Enhanced formation of NPIW seem to be driven by the perturbation of sea ice formation and sea surface salinity oscillation in high latitude North Pacific through atmospheric and oceanic teleconnection. During the B/A, decreased sedimentary oxygenation likely resulted from an upward penetration of aged deep water into the intermediate-depth in the North Pacific, corresponding to a resumption of Atlantic Meridional Overturning Circulation.

scholarly journals Millennial-scale variations in sedimentary oxygenation in the western subtropical North Pacific and its links to North Atlantic climate

2020 ◽  
Vol 16 (1) ◽  
pp. 387-407 ◽  
Author(s):  
Jianjun Zou ◽  
Xuefa Shi ◽  
Aimei Zhu ◽  
Selvaraj Kandasamy ◽  
Xun Gong ◽  
...  
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Deep Ocean ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Intermediate Water ◽  
The North ◽  
Geochemical Parameters ◽  
The North Pacific ◽  
Millennial Scale

Abstract. The deep-ocean carbon cycle, especially carbon sequestration and outgassing, is one of the mechanisms to explain variations in atmospheric CO2 concentrations on millennial and orbital timescales. However, the potential role of subtropical North Pacific subsurface waters in modulating atmospheric CO2 levels on millennial timescales is poorly constrained. An increase in the respired CO2 concentration in the glacial deep-ocean due to biological pump generally corresponds to deoxygenation in the ocean interior. This link thus offers a chance to study oceanic ventilation and coeval export productivity based on redox-controlled sedimentary geochemical parameters. Here, we investigate a suite of geochemical proxies in a sediment core from the Okinawa Trough to understand sedimentary oxygenation variations in the subtropical North Pacific over the last 50 000 years (50 ka). Our results suggest that enhanced mid-depth western subtropical North Pacific (WSTNP) sedimentary oxygenation occurred during cold intervals and after 8.5 ka, while oxygenation decreased during the Bölling-Alleröd (B/A) and Preboreal. The enhanced oxygenation during cold spells is linked to the North Pacific Intermediate Water (NPIW), while interglacial increase after 8.5 ka is linked to an intensification of the Kuroshio Current due to strengthened northeast trade winds over the tropics. The enhanced formation of the NPIW during Heinrich Stadial 1 (HS1) was likely driven by the perturbation of sea ice formation and sea surface salinity oscillations in the high-latitude North Pacific. The diminished sedimentary oxygenation during the B/A due to a decreased NPIW formation and enhanced export production, indicates an expansion of the oxygen minimum zone in the North Pacific and enhanced CO2 sequestration at mid-depth waters, along with the termination of atmospheric CO2 concentration increase. We attribute the millennial-scale changes to an intensified NPIW and enhanced abyss flushing during deglacial cold and warm intervals, respectively, closely related to variations in North Atlantic Deep Water formation.

scholarly journals Sensitivity of the Simulated Distributions of Water Masses, CFCs, and Bomb 14C to Parameterizations of Mesoscale Tracer Transports in a Model of the North Pacific

2006 ◽  
Vol 36 (3) ◽  
pp. 273-285 ◽  
Author(s):  
Yongfu Xu ◽  
Shigeaki Aoki ◽  
Koh Harada
Keyword(s):  
North Pacific ◽  
General Circulation ◽  
Western North Pacific ◽  
North Pacific Ocean ◽  
Circulation Model ◽  
Water Masses ◽  
Intermediate Water ◽  
North Pacific Intermediate Water ◽  
The North ◽  
The North Pacific

Abstract A basinwide ocean general circulation model of the North Pacific Ocean is used to study the sensitivity of the simulated distributions of water masses, chlorofluorocarbons (CFCs), and bomb carbon-14 isotope (14C) to parameterizations of mesoscale tracer transports. Five simulations are conducted, including a run with the traditional horizontal mixing scheme and four runs with the isopycnal transport parameterization of Gent and McWilliams (GM). The four GM runs use different values of isopycnal and skew diffusivities. Simulated results show that the GM mixing scheme can help to form North Pacific Intermediate Water (NPIW). Greater isopycnal diffusivity enhances formation of NPIW. Although greater skew diffusivity can also generate NPIW, it makes the subsurface too fresh. Results from simulations of CFC uptake show that greater isopycnal diffusivity generates the best results relative to observations in the western North Pacific. The model generally underestimates the inventories of CFCs in the western North Pacific. The results from simulations of bomb 14C reproduce some observed features. Greater isopycnal diffusivity generates a longitudinal gradient of the inventory of bomb 14C from west to east, whereas greater skew diffusivity makes it reversed. It is considered that the ratio of isopycnal diffusivity to skew diffusivity is important. An increase in isopycnal diffusivity increases storage of passive tracers in the subtropical gyre.

Satellite-Derived Tropical Cyclone Intensity in the North Pacific Ocean Using the Deviation-Angle Variance Technique

2014 ◽  
Vol 29 (3) ◽  
pp. 505-516 ◽  
Author(s):  
Elizabeth A. Ritchie ◽  
Kimberly M. Wood ◽  
Oscar G. Rodríguez-Herrera ◽  
Miguel F. Piñeros ◽  
J. Scott Tyo
Keyword(s):  
Tropical Cyclone ◽  
North Atlantic ◽  
North Pacific ◽  
Western North Pacific ◽  
North Pacific Ocean ◽  
Deviation Angle ◽  
Intensity Estimation ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific

Abstract The deviation-angle variance technique (DAV-T), which was introduced in the North Atlantic basin for tropical cyclone (TC) intensity estimation, is adapted for use in the North Pacific Ocean using the “best-track center” application of the DAV. The adaptations include changes in preprocessing for different data sources [Geostationary Operational Environmental Satellite-East (GOES-E) in the Atlantic, stitched GOES-E–Geostationary Operational Environmental Satellite-West (GOES-W) in the eastern North Pacific, and the Multifunctional Transport Satellite (MTSAT) in the western North Pacific], and retraining the algorithm parameters for different basins. Over the 2007–11 period, DAV-T intensity estimation in the western North Pacific results in a root-mean-square intensity error (RMSE, as measured by the maximum sustained surface winds) of 14.3 kt (1 kt ≈ 0.51 m s−1) when compared to the Joint Typhoon Warning Center best track, utilizing all TCs to train and test the algorithm. The RMSE obtained when testing on an individual year and training with the remaining set lies between 12.9 and 15.1 kt. In the eastern North Pacific the DAV-T produces an RMSE of 13.4 kt utilizing all TCs in 2005–11 when compared with the National Hurricane Center best track. The RMSE for individual years lies between 9.4 and 16.9 kt. The complex environment in the western North Pacific led to an extension to the DAV-T that includes two different radii of computation, producing a parametric surface that relates TC axisymmetry to intensity. The overall RMSE is reduced by an average of 1.3 kt in the western North Pacific and 0.8 kt in the eastern North Pacific. These results for the North Pacific are comparable with previously reported results using the DAV for the North Atlantic basin.

scholarly journals An Atlantic-driven rapid circulation change in the North Pacific Ocean during the late 1990s

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chau-Ron Wu ◽  
Yong-Fu Lin ◽  
You-Lin Wang ◽  
Noel Keenlyside ◽  
Jin-Yi Yu
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Kuroshio Current ◽  
Climate Trends ◽  
North Pacific Subtropical Gyre ◽  
Inter Tropical Convergence Zone ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific

Abstract Interbasin interactions have been increasingly emphasized in recent years due to their roles in shaping climate trends and the global warming hiatus in the northern hemisphere. The profound influence from the North Atlantic on the Tropical Pacific has been a primary focus. In this study, we conducted observational analyses and numerical modeling experiments to show that the North Atlantic has also strongly influenced the Extratropical North Pacific. A rapid and synchronous change in the atmospheric and oceanic circulations was observed in the North Pacific during the late 1990s. The change was driven by the transbasin influence from the Atlantic Ocean. During the positive phase of the Atlantic Multidecadal Oscillation (AMO) since the 1990s, the anomalously warm North Atlantic triggers a series of zonally symmetric and asymmetric transbasin teleconnections involving the Inter-tropical Convergence Zone (ITCZ), Walker and Hadley circulations, and Rossby wave propagation that lead to a decrease in wind stress curls over the Pacific subtropics, resulting in an abrupt weakening in the North Pacific subtropical gyre (NPSG) and the Kuroshio Current.

Sign in / Sign up

Export Citation Format

Share Document