Dissolved inorganic Radiocarbon content of the Western Coral sea: Implications for Intermediate and Deep Water Circulation

Radiocarbon ◽  
2019 ◽  
Vol 61 (6) ◽  
pp. 1685-1696 ◽  
Author(s):  
Aymeric PM Servettaz ◽  
Yusuke Yokoyama ◽  
Shoko Hirabayashi ◽  
Markus Kienast ◽  
Yosuke Miyairi ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Deep Water ◽  
South Pacific ◽  
Intermediate Water ◽  
The South ◽  
Central Pacific ◽  
South Pacific Ocean ◽  
Deep Waters ◽  
Coral Sea ◽  
South Pacific Gyre

ABSTRACTThe South Pacific Ocean contributes to the global carbon cycle by exchanging CO2 between the atmosphere and intermediate to deep water masses. The path of the Antarctic Intermediate Water (AAIW) in the South Pacific gyre has been inferred from salinity, oxygen, and nutrient measurements, but radiocarbon (14C) measurements—a direct tracer of the carbon cycle—remain sparse. Here, we present the first radiocarbon profiles in the western Coral Sea and compare our measurements with South Pacific stations from GLODAPv2, a database of ocean hydrochemistry. Surface and subsurface waters in the Coral Sea cannot be attributed to a single source based on their Δ14C signatures, and we observe a penetration of bomb-produced 14C. AAIW in the western Coral Sea shows Δ14C values comparable to those in the South Pacific gyre, consistent with circulation of AAIW in the lower part of the southern equatorial current. The deep waters of the western Coral Sea have significantly higher 14C than the South Pacific at the same isopycnal, consistent with a northward intrusion of Circumpolar Deep Water from the Tasman Sea, along with a westward influx of deep waters from the Central Pacific. In accordance with silicate concentrations published previously, this shows the dual origin of deep waters in the Coral Sea.

scholarly journals Variability of Antarctic intermediate water properties in the South Pacific Ocean

2006 ◽  
Vol 3 (6) ◽  
pp. 2021-2058 ◽  
Author(s):  
M. Tomczak
Keyword(s):  
Time Series Data ◽  
World Ocean ◽  
South Pacific ◽  
Series Data ◽  
Intermediate Water ◽  
The South ◽  
Salinity Field ◽  
Antarctic Intermediate Water ◽  
Argo Float ◽  
South Pacific Ocean

Abstract. Argo float time series data are used to study the salinity field at the depth of the salinity minimum produced by Antarctic Intermediate Water (AAIW). It is found that far from showing the smooth erosion of the minimum that would result from diffusive flow, the salinity field is characterized by features of geostrophic turbulence such as fronts, eddies and intrusions. Comparison of the Argo float observations with the climatology of the World Ocean Atlas (WOA) reveals significant differences between the two data sets. Some of the differences may have their origin in problems with the WOA data density in remote regions of the South Pacific, but most are more likely produced by interannual variations of the AAIW salinity field.

scholarly journals Intermediate water flows in the western South Pacific: as revealed by individual Argo floats trajectories and a model re-analysis

2018 ◽  
Vol 15 (13) ◽  
pp. 4103-4124 ◽  
Author(s):  
Simon Barbot ◽  
Anne Petrenko ◽  
Christophe Maes
Keyword(s):  
South Pacific ◽  
Velocity Shear ◽  
Cyclonic Eddy ◽  
Intermediate Water ◽  
Argo Floats ◽  
Mesoscale Dynamics ◽  
Zonal Jets ◽  
The North ◽  
South Pacific Ocean ◽  
Deep Waters

Abstract. Thanks to the autonomous Argo floats of the OUTPACE cruise (Oligotrophy to UlTra-oligotrophy PACific Experiment) and of the THOT (TaHitian Ocean Time series) project, some features of intermediate-flow dynamics, at around 1000 m depth, within the central and western South Pacific Ocean (around 19∘ S, 156∘ E–150∘ W) are described. In the Coral Sea, we highlight minima in dissolved oxygen of 140 µmol kg−1 that are associated with the signature of a southward transport of waters between two zonal jets: from the North Vanuatu Jet to the North Caledonia Jet. This transport takes place in the core of a cyclonic eddy or via the path between a cyclonic eddy and an anticyclonic one, highlighting the importance of mesoscale dynamics in upper thermocline and surface layers. Further east, we observe a strong meridional velocity shear with long-term float trajectories going either eastward or westward in the lower thermocline. More interestingly, these trajectories also exhibit some oscillatory features. Those trajectories can be explained by a single Rossby wave of 160-day duration and 855 km wavelength. Considering the thermohaline context, we confirm the meridional shear of zonal velocity and highlight a permanent density front that corresponds to the interface between Antarctic intermediate waters and North Pacific deep waters. Hence both circulation and thermohaline contexts are highly prone to instabilities and wave propagation.

scholarly journals Variability of Antarctic intermediate Water properties in the South Pacific Ocean

Ocean Science ◽  
2007 ◽  
Vol 3 (3) ◽  
pp. 363-377 ◽  
Author(s):  
M. Tomczak
Keyword(s):  
Time Series Data ◽  
World Ocean ◽  
South Pacific ◽  
Series Data ◽  
Intermediate Water ◽  
The South ◽  
Salinity Field ◽  
Antarctic Intermediate Water ◽  
Argo Float ◽  
South Pacific Ocean

Abstract. Argo float time series data are used to study the salinity field at the depth of the salinity minimum produced by Antarctic Intermediate Water (AAIW). It is found that far from showing the smooth erosion of the minimum that would result from diffusive flow, the salinity field is characterized by features of geostrophic turbulence such as fronts, eddies and intrusions. Comparison of the Argo float observations with the climatology of the World Ocean Atlas (WOA) reveals significant differences between the two data sets. Some of the differences may have their origin in problems with the WOA data density in remote regions of the South Pacific, but most are more likely produced by interannual variations of the AAIW salinity field.

scholarly journals Evaluation of the Impacts of Climate Change on Albacore Distribution in the South Pacific Ocean by Using Ensemble Forecast

2021 ◽  
Vol 8 ◽  
Author(s):  
Yi-Jay Chang ◽  
Jhen Hsu ◽  
Po-Kai Lai ◽  
Kuo-Wei Lan ◽  
Wen-Pei Tsai
Keyword(s):  
Climate Change ◽  
Pacific Ocean ◽  
Relative Abundance ◽  
General Circulation ◽  
South Pacific ◽  
The South ◽  
Central Pacific ◽  
South Pacific Ocean ◽  
Rcp 8.5 ◽  
Longline Fisheries

South Pacific albacore (Thunnus alalunga) is a highly migratory tuna species widely distributed throughout 0°–50°S in the South Pacific Ocean. Climate-driven changes in the oceanographic condition largely influence the albacore distribution, relative abundance, and the consequent availability by the longline fisheries. In this study, we examined the habitat preference and spatial distribution of south Pacific albacore using a generalized additive model fitted to the longline fisheries data from the Western and Central Pacific Fisheries Commission (WCPFC) and Inter-American Tropical Tuna Commission (IATTC). Future projections of albacore distributions (2020, 2050, and 2080) were predicted by using an ensemble modeling approach produced from various atmosphere-ocean general circulation models and anthropogenic emission scenarios (i.e., RCP 4.5 and RCP 8.5) to reduce the uncertainty in the projected changes. The dissolved oxygen concentration at 100 meters (DO100) and sea surface temperature (SST) were found to have the most substantial effects on the potential albacore distribution that the albacore preferred in the habitat with DO100 of 0.2–0.25 mmol L–1 and SST of 13–22°C. This study suggested that the northern boundary of albacore preferred habitat is expected to shift southward by about 5° latitudes, and the relative abundance is expected to gradually increase in the area south of 30°S from 2020 to 2080 for both RCP scenarios, especially with a higher degree of change for the RCP 8.5. Moreover, the albacore relative abundance is projected to decrease in the most exclusive economic zones (EEZs) of countries and territories in the South Pacific Ocean by 2080. These findings could lend important implications on the availability of tuna resources to the fisheries and subsequent evaluation of tuna conservation and management under climate change.

The Flow of Water into the Deep Sea Basins of the Western South Pacific Ocean

1961 ◽  
Vol 12 (1) ◽  
pp. 1 ◽  
Author(s):  
K Wyrtki
Keyword(s):  
Pacific Ocean ◽  
Deep Sea ◽  
New Caledonia ◽  
Potential Temperature ◽  
South Pacific ◽  
Central Pacific ◽  
South Pacific Ocean ◽  
Coral Sea ◽  
New Hebrides ◽  
Bottom Waters

The hydrographic conditions in the deep sea basins of the western South Pacific Ocean are analysed using relations between potential temperature and salinity, based on observations made from H.M.A.S. Gascoyne in 1960. It is shown that the bottom waters in the Coral Sea Basin and in the Solomon Basin are both characterized by a comparatively high salinity and that they come from the East Australian Basin. The bottom waters in the New Hebrides Basin, the New Caledonia Trough, and the Fiji Basin come from the central Pacific Basin. The water in the New Hebrides Basin and that in the New Caledonia Trough both have a slight admixture of water of higher salinity which has escaped over the ridges on the east sides of the Coral Sea Basin and the Solomon Basin. The Coral Sea Basin and the Solomon Basin considered as a unit is an example, probably the unique case, of . the inflow into a basin occurring at a higher level than the outflow. The sill depths of the different basins are determined by using potential temperature characteristics. The water exchange of the Coral Sea Basin is discussed theoretically. The upward velocity at depths between 3000 and 4000 m is of the order of 1.5 × 10-5 cm/sec and the rate of inflow 0.04 million m3/sec.

scholarly journals Heterotrophic bacterial production in the eastern South Pacific: longitudinal trends and coupling with primary production

2008 ◽  
Vol 5 (1) ◽  
pp. 157-169 ◽  
Author(s):  
F. Van Wambeke ◽  
I. Obernosterer ◽  
T. Moutin ◽  
S. Duhamel ◽  
O. Ulloa ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Primary Production ◽  
Bacterial Production ◽  
South Pacific ◽  
Leucine Incorporation ◽  
The South ◽  
Phytoplankton Primary Production ◽  
South Pacific Ocean ◽  
Wide Range ◽  
South Pacific Gyre

Abstract. Spatial variation of heterotrophic bacterial production and phytoplankton primary production were investigated across the eastern South Pacific Ocean (−141° W, −8° S to −72° W, −35° S) in November–December 2004. Bacterial production (3H leucine incorporation) integrated over the euphotic zone encompassed a wide range of values, from 43 mg C m−2 d−1 in the hyper-oligotrophic South Pacific Gyre to 392 mg C m−2 d−1 in the upwelling off Chile. In the gyre (120° W, 22° S) records of low phytoplankton biomass (7 mg Total Chla m−2) were obtained and fluxes of in situ 14C-based particulate primary production were as low as 153 mg C m−2 d−1, thus equal to the value considered as a limit for primary production under strong oligotrophic conditions. Average rates of 3H leucine incorporation rates, and leucine incorporation rates per cell (5–21 pmol l−1 h−1 and 15–56×10−21 mol cell−1 h−1, respectively) determined in the South Pacific gyre, were in the same range as those reported for other oligotrophic subtropical and temperate waters. Fluxes of dark community respiration, determined at selected stations across the transect varied in a narrow range (42–97 mmol O2 m−2 d−1), except for one station in the upwelling off Chile (245 mmol O2 m−2 d−1). Bacterial growth efficiencies varied between 5 and 38%. Bacterial carbon demand largely exceeded 14C particulate primary production across the South Pacific Ocean, but was lower or equal to gross community production.

scholarly journals An Exchange Window for the Injection of Antarctic Intermediate Water into the South Pacific

2007 ◽  
Vol 37 (1) ◽  
pp. 31-49 ◽  
Author(s):  
Daniele Iudicone ◽  
Keith B. Rodgers ◽  
Richard Schopp ◽  
Gurvan Madec
Keyword(s):  
Southern Ocean ◽  
Large Scale ◽  
South Pacific ◽  
Intermediate Water ◽  
The South ◽  
Antarctic Intermediate Water ◽  
South Pacific Ocean ◽  
The Pacific ◽  
Basin Scale ◽  
Circumpolar Current

Abstract Antarctic Intermediate Water (AAIW) occupies the intermediate horizon of most of the world oceans. Formed in the Southern Ocean, it is characterized by a relative salinity minimum. With a new, denser in situ National Oceanographic Data Center dataset, the authors have reanalyzed the export characteristics of AAIW from the Southern Ocean into the South Pacific Ocean. These new data show that part of the AAIW is exported from the subpolar frontal region by the large-scale circulation through an exchange window of 10° width situated east of 90°W in the southeast corner of the Pacific basin. This suggests the origin of this water to be in the Antarctic Circumpolar Current. A set of numerical modeling experiments has been used to reproduce these observed features and to demonstrate that the dynamics of the exchange window is controlled by the basin-scale meridional pressure gradient. The exchange of AAIW between the Southern and Pacific Oceans must therefore be understood in the context of the large basin-scale dynamical balance rather than simply local effects.

scholarly journals Carbon and nitrogen uptake in the South Pacific Ocean: evidence for efficient dinitrogen fixation and regenerated production leading to large accumulation of dissolved organic matter in nitrogen-depleted waters

2007 ◽  
Vol 4 (5) ◽  
pp. 3531-3579 ◽  
Author(s):  
P. Raimbault ◽  
N. Garcia
Keyword(s):  
Organic Matter ◽  
Nitrogen Uptake ◽  
Inorganic Nitrogen ◽  
South Pacific ◽  
Dinitrogen Fixation ◽  
The South ◽  
New Production ◽  
Marquesas Islands ◽  
South Pacific Ocean ◽  
South Pacific Gyre

Abstract. A major goal of the BIOSOPE cruise on the R/V Atalante to the South Pacific Ocean (conducted in October–November 2004) was to establish rate of productivity along a longitudinal section across the oligotrophic South Pacific Gyre (SPG), and compared these measurements with those obtained in nutrient–repleted waters from Chilean upwelling and around Marquesas Islands. A dual 13C/15N isotopic technique was used to estimate rates of carbon fixation, inorganic nitrogen uptake (including dinitrogen fixation), ammonium (NH4) and nitrate (NO3) regeneration, and dissolved organic nitrogen (DON) release resulting from both NH4 and NO3 uptake. The SPG had revealed the lowest rates of primary production (0.1 gC.m−2.d−1), while rates were 7 to 20 fold higher around the Marquesas Islands and in the Chilean upwelling, respectively. In this very low productive area, most of primary production was sustained by active regeneration processes which fuelled up to 95% of the biological nitrogen demand. Since nitrification was very active in the surface layer and often balanced the biological demand of nitrate, dinitrogen fixation, although acting at low daily rate (≈1–2 nmoles l−1d−1), sustained the main part of new production. Then, new production in the SPG (0.008±0.007 gC m−2.d−1) was two orders of magnitude lower than this measured in the upwelling where it essentially sustained by nitrate (0.69±0.49 gC.m−2.d−1). In the whole investigated region, the percentage of nitrogen release as DON represented a large part of the inorganic nitrogen uptake (13–15% in average), and reaching 26–41% in the SPG where the production of DON appeared to be a major part of the nitrogen cycle. Due to the lack of annual vertical mixing and very low lateral advection, the high release rates could explain the large accumulation of dissolved organic matter observed in the nitrogen-depleted and low productive waters of the South Pacific Gyre.

scholarly journals Ultra low level deep water 137Cs activity in the South Pacific Ocean

2009 ◽  
Vol 282 (3) ◽  
pp. 781-785 ◽  
Author(s):  
M. Aoyama ◽  
Y. Hamajima ◽  
M. Fukasawa ◽  
T. Kawano ◽  
S. Watanabe
Keyword(s):  
Pacific Ocean ◽  
Deep Water ◽  
South Pacific ◽  
137Cs Activity ◽  
The South ◽  
Low Level ◽  
South Pacific Ocean
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