Abyssal circulation in the Argentine Basin

Smythe-Wright, Denise; Boswell, Stephen M.

doi:10.1029/98jc00142

Cited by 34 publications

(13 citation statements)

References 17 publications

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“…Such a model requires the primary flow to be as a topographically steered boundary current, and as noted in section 1, this is not necessarily the case here. CFC concentrations comparable to those found in the deep boundary current of the Argentine Basin have been observed over a much broader region on the eastern side of the basin [e.g., Smythe-Wright and Boswell, 1998]. Furthermore, in running simple advection/diffusion plume models, knowing where the water is forming is necessary.…”

Section: Quantifying the Atlantic Ocean Componentsupporting

confidence: 53%

Chlorofluorocarbon‐derived formation rates of the deep and bottom waters of the Weddell Sea

Meredith¹,

Watson²,

Scoy³

et al. 2001

J. Geophys. Res.

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Abstract. The spreading and mixing of deep and bottom waters from the Weddell Sea (originating with potential temperature <0øC) are investigated through analysis of new and historical CFC measurements. We investigate the component that enters the southern Indian Ocean with a simple one-dimensional advection-diffusion model of the deep boundary current. This model does not require a condition of mixing solely with tracer-free water to be imposed. As boundary conditions, we derive time histories for the CFC concentrations of newly formed Weddell Sea deep and bottom waters. A range of best fit velocities is obtained by determining which model velocities produce model tracer concentrations closest to measured concentrations. From this, we derive a formation rate of 3.24-1.5 Sv for the waters originating with temperatures lower than 0øC that subsequently enter the southern Indian Ocean. This compares to an upper limit for these waters of 5.7 Sv derived from the CFC-11/CFC-12 ratio. Whilst the former value is dependent on the highly idealized concepts of the model used, the latter is a more robust upper limit. Using the CFC-11/CFC-12 ratio measured at Vema Channel during the World Ocean Circulation Experiment cruise A23, an upper limit of 0.9 Sv is derived for the formation rate of waters colder than 0øC that enter the South Atlantic. Overall, an upper limit of 6.6 Sv is derived for the rate of formation of the deep and bottom waters of the Weddell Sea. A better representation is obtained by combining the upper limit to the South Atlantic component with the model-derived southern Indian Ocean estimate; we thus estimate the formation rate of the deep and bottom waters in the Weddell Sea to be 3.74-1.6 Sv. Whilst the range obtained is large and the assumptions implicit in the calculations are potentially significant, we believe this more realistically represents the true formation rate than estimates derived using an imposed condition of tracer-free mixing. The range can be narrowed in future as more data become available.

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Section: Quantifying the Atlantic Ocean Componentsupporting

confidence: 53%

Chlorofluorocarbon‐derived formation rates of the deep and bottom waters of the Weddell Sea

Meredith¹,

Watson²,

Scoy³

et al. 2001

J. Geophys. Res.

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“…Many years later different vintages of WSDW will arrive at the Vema Sill. Calculations by Smythe‐Wright and Boswell [1998] based on WOCE chlorofluorocarbon estimates indicate that the time scale of the abyssal circulation in the Argentine Basin is approximately 30 years. The implicit oceanic response time attends variations in abyssal watermass characteristics delayed and modified by vertical mixing with overlying warmer water [ Zenk , 2007].…”

Section: Discussionmentioning

confidence: 99%

Decadal warming of the coldest Antarctic Bottom Water flow through the Vema Channel

Zenk

Morozov

2007

Geophysical Research Letters

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A decadal warming trend of Antarctic Bottom Water flowing through the Vema Channel is reanalyzed. Our data base consists of 94 high precision, full depth stations from 19 visits to the Vema Sill plus twelve stopovers at two additional key locations. Originally a long‐term temperature increase in the near‐bottom jet was noted from 1992 onward, after a period of rather constant abyssal temperatures since 1972. From today's perspective the apparent stagnant temperature level until 1991 can be interpreted as a period of feeble rising in comparison with a perspicuous warming trend of 2.8 mK yr−1 in the following 15 years. However, the clearly manifested temperature rise is superimposed with fluctuations. For the first time the available time series appears long enough to indicate an associated slight freshening of the bottom water. An attempt is made to trace the observed variability back to its source region in the Weddell Sea.

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“… Orsi et al [1999] described the AABW as a mixture of Lower Circumpolar Deep Water (LCDW) and dense water fed from Antarctic margins. In addition to the Weddell Sea Bottom Water (WSBW), other AABW sources were reported, based on measurements of CFCs which are tracers of water ventilation [ Smythe‐Wright and Boswell , 1998; Meredith et al , 2000; Doney and Hecht , 2002]. The unventilated LCDW is characterised by low oxygen and low CFC content and high silicate concentrations, while the recently formed Weddell Sea Deep Water (WSDW) is colder and less rich in silica but richer in oxygen and in atmospheric tracers [ Weiss et al , 1979].…”

Section: Introductionmentioning

confidence: 99%

Variability of AABW properties in the equatorial channel at 35°W

Andrié

Gouriou

Bourlès

et al. 2003

Geophysical Research Letters

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[1] Hydrological data and tracer (silicate, oxygen and CFCs) analyses have been performed in order to describe the time and space variability of the characteristics and transport of the Antarctic Bottom Water (AABW) entering the equatorial channel at 35°W. The 35°W sections were sampled in the tropical Atlantic during several cruises from 1993 to 1999 as part of the international WOCE and CLIVAR efforts. Data for the 1990s reveal a slight warming trend superimposed on significant variability due to the seasonal changes of AABW transports. Data from previous cruises made in the 1970s and 1980s complete the time-series and show that, over the last three decades, the maximal AABW input occurred in the early 1990s.

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Abyssal circulation in the Argentine Basin

Cited by 34 publications

References 17 publications

Chlorofluorocarbon‐derived formation rates of the deep and bottom waters of the Weddell Sea

Chlorofluorocarbon‐derived formation rates of the deep and bottom waters of the Weddell Sea

Decadal warming of the coldest Antarctic Bottom Water flow through the Vema Channel

Variability of AABW properties in the equatorial channel at 35°W

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