Particulate organic carbon export from the North and South Atlantic gyres: The 234Th/238U disequilibrium approach

North and South Atlantic lateral volume exchange is a key component of the Atlantic Meridional Overturning Circulation (AMOC) embedded in Earth’s climate. Northward AMOC heat transport within this exchange mitigates the large heat loss to the atmosphere in the northern North Atlantic. Because of inadequate climate data, observational basin-scale studies of net interbasin exchange between the North and South Atlantic have been limited. Here ten independent climate datasets, five satellite-derived and five analyses, are synthesized to show that North and South Atlantic climatological net lateral volume exchange is partitioned into two seasonal regimes. From late-May to late-November, net lateral volume flux is from the North to the South Atlantic; whereas from late-November to late-May, net lateral volume flux is from the South to the North Atlantic. This climatological characterization offers a framework for assessing seasonal variations in these basins and provides a constraint for climate models that simulate AMOC dynamics.

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Migration of exotic species of ammonites during highstands of sea level

The Paleontological Society Special Publications ◽

10.1017/s2475262200008844 ◽

1992 ◽

Vol 6 ◽

pp. 324-324

Author(s):

Keith Young

Keyword(s):

North America ◽

South America ◽

Exotic Species ◽

Sea Level ◽

South Atlantic ◽

Horn Of Africa ◽

Mozambique Channel ◽

The North ◽

North And South ◽

Early Late

In northeastern Chihuahua and Trans-Pecos Texas, in the early Late Albian zone of Hysteroceras varicosum occurs the Boeseites romeri (Haas) fauna with B. romeri (Hass), B. perarmata (Hass), B. aff. barbouri (Haas), B. cf. howelli (Haas), B.proteus (Haas), Prohysteroceras cf. P. hanhaense Haas, Elobiceras sp., and Dipoloceras (?) sp. B. perarmata has also been collected at Cerro Mercado, near Monclova, Coahuila. Haas originally described this fauna from Angola. Now, from rocks in the same zone in the Sierra Mojada, Coahuila, Mexico, there is a form related to if not identical with Hysteroceras famelicum Van Hoepen, also originally described from Angola and also from the zone of Hysteroceras varicosum.These fossils are known only from southern North America and Angola; they have not been described from the European Tethys. In 1984 I suggested that during the highstand of sea level of the early Late Albian (Hysteroceras varicosum zone) these ammonites migrated from Angola to Mexico and Trans-Pecos Texas via an epeiric seaway extending across the sag between South America and Africa proposed by Kennedy and Cooper. This would be twelve to fifteen million years prior to an oceanic connection between the North and South Atlantic.I would now ask, can similar epeiric seas and highstands of sea level explain the migration of successive European, Tethyan, Jurassic ammonite faunas down the Mozambique Channel and around the horn of Africa into the Neuquen Basin of Argentina before Africa and Antarctica separated, as proposed by Spath.

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234Th-derived particulate organic carbon export in the Prydz Bay, Antarctica

Journal of Radioanalytical and Nuclear Chemistry ◽

10.1007/s10967-013-2842-y ◽

2013 ◽

Vol 299 (1) ◽

pp. 621-630 ◽

Cited By ~ 2

Author(s):

Hao Ma ◽

Zhi Zeng ◽

Jianhua He ◽

Zhengbing Han ◽

Wuhui Lin ◽

...

Keyword(s):

Organic Carbon ◽

Particulate Organic Carbon ◽

Prydz Bay ◽

Carbon Export

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Similarity in microbial amino acid uptake in surface waters of the North and South Atlantic (sub-)tropical gyres

Progress In Oceanography ◽

10.1016/j.pocean.2011.05.006 ◽

2011 ◽

Vol 91 (4) ◽

pp. 437-446 ◽

Cited By ~ 6

Author(s):

Polly G. Hill ◽

Isabelle Mary ◽

Duncan A. Purdie ◽

Mikhail V. Zubkov

Keyword(s):

Amino Acid ◽

Surface Waters ◽

Amino Acid Uptake ◽

South Atlantic ◽

Acid Uptake ◽

The North ◽

North And South

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The export flux of particulate organic carbon derived from 210Po∕210Pb disequilibria along the North Atlantic GEOTRACES GA01 transect: GEOVIDE cruise

Biogeosciences ◽

10.5194/bg-16-309-2019 ◽

2019 ◽

Vol 16 (2) ◽

pp. 309-327 ◽

Cited By ~ 3

Author(s):

Yi Tang ◽

Nolwenn Lemaitre ◽

Maxi Castrillejo ◽

Montserrat Roca-Martí ◽

Pere Masqué ◽

...

Keyword(s):

Organic Carbon ◽

Particulate Organic Carbon ◽

North Atlantic ◽

Study Region ◽

Vertical Advection ◽

Export Flux ◽

The North ◽

Iberian Basin ◽

Poc Export ◽

The North Atlantic

Abstract. The disequilibrium between 210Po activity and 210Pb activity in seawater samples was determined along the GEOTRACES GA01 transect in the North Atlantic during the GEOVIDE cruise (May–June 2014). A steady-state model was used to quantify vertical export of particulate 210Po. Vertical advection was incorporated into one version of the model using time-averaged vertical velocity, which had substantial variance. This resulted in large uncertainties for the 210Po export flux in this model, suggesting that those calculations of 210Po export fluxes should be used with great care. Despite the large uncertainties, there is no question that the deficits of 210Po in the Iberian Basin and at the Greenland Shelf have been strongly affected by vertical advection. Using the export flux of 210Po and the particulate organic carbon (POC) to 210Po ratio of total (> 1 µm) particles, we determined the POC export fluxes along the transect. Both the magnitude and efficiency of the estimated POC export flux from the surface ocean varied spatially within our study region. Export fluxes of POC ranged from negligible to 10 mmol C m−2 d−1, with enhanced POC export in the Labrador Sea. The cruise track was characterized by overall low POC export relative to net primary production (export efficiency < 1 %–15 %), but relatively high export efficiencies were seen in the basins where diatoms dominated the phytoplankton community. The particularly low export efficiencies in the Iberian Basin, on the other hand, were explained by the dominance of smaller phytoplankton, such as cyanobacteria or coccolithophores. POC fluxes estimated from the 210Po∕210Pb and 234Th∕238U disequilibria agreed within a factor of 3 along the transect, with higher POC estimates generally derived from 234Th. The differences were attributed to integration timescales and the history of bloom events.

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