Origin and evolution of water masses near the Antarctic continental margin: Evidence from H218O/H216O ratios in seawater

Jacobs, Stanley S.; Fairbanks, Richard G.; Horibe, Yoshio

doi:10.1029/ar043p0059

Cited by 289 publications

(277 citation statements)

References 51 publications

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“…Ice input to the Ross Ice Shelf drainage basin, including precipitation on the ice shelf, has been estimated at 300 kms a-1 (Zotikov and others, 1974), 327 kms a-1 (Doake, 1985), and 248 :I: 40 km' a-1 (Bentley, 1985 (Jacobs and others, 1985). Contrary to most previous reports (e.g.…”

Section: Parts Of Ross Lee Shelf Thickness Maps Compiled By (A) Scottcontrasting

confidence: 50%

The Recent Advance of the Ross Ice Shelf Antarctica

1986

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ABSTRACT. The seaward edge of the Ross Ice Shelf advanced northward at a minimum average velocity of 0.8 km a-1 between 1962 and 1985. That advance approximated velocities that have been obtained from glac~ological data, indicatin~ little r~cent wastage by . iceberg calvmg. West of long. 178 E., the Ice shelf has attamed its most northerly position in the past 145 years, and has not experienced a major calving episode for at least 75 years. Since 1841 the ice-front position has advanced and retreated within a lone from about lat. 77 °10, S. (near long. 171°E.) to lat. 78 40' S. (near long. 164°W.). The central ice front is now farthest south but has the highest advance rate. Calving may occur at more frequent intervals in that sector, which also over lies the warmest ocean currents that flow into the sub-ice-shelf cavity. Available information on ice-shelf advance, thickness, spreading rate, and surface accumulation indicates a basal melting rate around 3 m a-1 near the ice front. These data and independent estimates imply that basal melting is nearly as large a factor as iceberg calving in maintaining the ice-shelf mass balance.

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Section: Parts Of Ross Lee Shelf Thickness Maps Compiled By (A) Scottcontrasting

confidence: 50%

The Recent Advance of the Ross Ice Shelf Antarctica

1986

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“…This process increases seawater salinity by brine rejection during ice formation and, as a consequence, the water is denser and sinks. From there, one branch moves northward toward the shelf break in the area off Cape Adare, while another branch moves southward beneath the Ross Ice Shelf taking part to the production of Deep Ice Shelf Water (DISW) (Jacobs et al 1985). This latter is colder (-2.038C) and less salty (34.68) than HSSW.…”

Section: Ross Sea Hydrologymentioning

confidence: 99%

“…It exhibits the highest temperature (1.178C) and is relatively salty (34.70). CDW episodically intrudes onto the shelf at specific locations related to bottom topography (Dinniman et al 2003), providing heat to the shelf waters (Jacobs et al 1985, Locarnini 1994, Jacobs & Giulivi 1998, Gouretsky 1999, Budillon et al 2000. Once on the shelf it mixes with fresher and colder shelf waters and is hence distinguished as Modified Circumpolar Deep Water (MCDW) (Jacobs et al 1970), identifiable by a subsurface maximum temperature (-0.848C) and minimum dissolved oxygen (Jacobs et al 1985, Budillon et al 1999.…”

Section: Ross Sea Hydrologymentioning

confidence: 99%

“…The High Salinity Shelf Water (HSSW) is the densest one, with salinity ranging from 34.75 to 35.00, increasing with depth and temperature close to the surface freezing point, between -1.95 and -1.758C (Budillon et al 2002). HSSW is formed during the winter in the western side of the Ross Sea, in the Terra Nova Bay polynya area, by continual formation and removal of new ice by the strong katabatic winds flowing down to the Antarctic plateau (Kurtz & Bromwich 1983, Jacobs et al 1985, Van Woert 1999. This process increases seawater salinity by brine rejection during ice formation and, as a consequence, the water is denser and sinks.…”

Section: Ross Sea Hydrologymentioning

confidence: 99%

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Anthropogenic carbon distribution in the Ross Sea, Antarctica

et al. 2007

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The Ross Sea is an area of dense water formation within the Southern Ocean, hence it potentially plays an important role for anthropogenic CO 2 sequestration : In order to estimate the penetration of anthropogenic carbon in the Ross Sea from total inorganic carbon (TCO 2 ) measurements carried out in 2002 -03 Antarctic Italian Expedition, we applied two independent models. Anthropogenic carbon was present throughout the water column. The highest concentrations were associated with the recently ventilated shelf waters, namely High Salinity Shelf Water (HSSW) and Ice Shelf Water (ISW), due to their recent contact with the atmosphere. The lowest concentrations were observed for Circumpolar Deep Water (CDW), due to its relatively older ventilation age. This water mass intrudes onto the shelf in some parts of the Ross Sea and hence is observed in the sampled section, where it is recognizable for its low O 2 and high TCO 2 concentrations. The overflow of the dense High Salinity Shelf Water out of the continental slope was observed in the area off Cape Adare. Since this recently formed shelf water contributes to the formation of the Antarctic Bottom Water (AABW), this process represents a pathway for anthropogenic carbon export down to the deep ocean.

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“…from freshwater deriving from the atmosphere), which is isotopically much lighter at high latitudes (e.g. Bauch et al, 1995;Jacobs et al, 1985;Meredith et al, 1999;Meredith et al, 2001;Schlosser et al, 1994). We use δ 18 O data here in this context.…”

mentioning

confidence: 99%

Variability in the freshwater balance of northern Marguerite Bay, Antarctic Peninsula: Results from δ18O

Meredith

Brandon

Wallace

et al. 2008

Deep Sea Research Part II: Topical Studies in Oceanography

109

126

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We investigate the seasonal variability in freshwater inputs to the Marguerite Bay region (Western Antarctic Peninsula) using a time series of oxygen isotopes in seawater from samples collected in the upper mixed layer of the ocean during 2002 and 2003. We find that meteoric water, mostly in the form of glacial ice melt, is the dominant freshwater source, accounting for up to 5% of the near-surface ocean during the austral summer. Sea ice melt accounts for a much smaller percentage, even during the summer (maximum around 1%). The seasonality in meteoric water input to the ocean (around 2% of the near-surface ocean) is not dissimilar to that of sea ice melt (around 2% in 2002 and 1% in 2003), contradicting the assumption that sea ice processes dominate the seasonal evolution of the physical ocean environment close to the Antarctic continent. Three full-depth profiles of oxygen isotopes collected in successive Decembers (2001, 2002 and 2003) indicate that around 4 m of meteoric water is present in the water column at this time of year, and around 1 m of sea ice formed from this same water column. The predominance of glacial melt is significant, since it is known to be an important factor in the operation of the ecosystem, for example by providing a source of nutrients and modifying the physical environment to control the spatial extent and magnitude of phytoplankton blooms.The Western Antarctic Peninsula is undergoing a very rapid change in climate, with increasing ocean and air temperatures, retreating glaciers and increases in precipitation associated with changes in atmospheric circulation. As climate change continues, we expect meteoric water inputs to the adjacent ocean to rise further. Sea ice in this sector of the Antarctic has shown a climatic decrease, thus we expect a reduction in oceanic sea ice melt fractions if this change continues. Continued monitoring of the oceanic freshwater budget at the western Peninsula is 2 needed to track these changes as they occur, and to better understand their ecological consequences.

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Origin and evolution of water masses near the Antarctic continental margin: Evidence from H218O/H216O ratios in seawater

Cited by 289 publications

References 51 publications

The Recent Advance of the Ross Ice Shelf Antarctica

The Recent Advance of the Ross Ice Shelf Antarctica

Anthropogenic carbon distribution in the Ross Sea, Antarctica

Variability in the freshwater balance of northern Marguerite Bay, Antarctic Peninsula: Results from δ18O

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