Rebound of shelf water salinity in the Ross Sea

Castagno, Pasquale; Capozzi, Vincenzo; DiTullio, Giacomo R.; Falco, Pierpaolo; Fusco, Giannetta; Rintoul, Stephen R.; Spezie, G.; Budillon, Giorgio

doi:10.1038/s41467-019-13083-8

Cited by 55 publications

(61 citation statements)

References 32 publications

(43 reference statements)

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“…The R/V Kaiyo-maru, Fisheries Agency of Japan, conducted a research cruise over 80°-150° E in the AAB, in the proximity of its seasonal ice edge, from December 2018 to March 2019. Previously in 1996, this part of the AAB was observed simultaneously by the R/V Aurora Australis 21 . Data from the section 115° E is supplemented by data obtained by the Training and Research Vessel Umitaka-maru, Tokyo University of Marine Science and Technology, obtained in 2015.…”

Section: Methodsmentioning

confidence: 84%

Reversal of freshening trend of Antarctic Bottom Water in the Australian-Antarctic Basin during 2010s

Aoki

Yamazaki

Hirano

et al. 2020

Sci Rep

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The Antarctic continental margin supplies the densest bottom water to the global abyss. From the late twentieth century, an acceleration in the long-term freshening of Antarctic Bottom Waters (AABW) has been detected in the Australian-Antarctic Basin. Our latest hydrographic observations reveal that, in the late 2010s, the freshening trend has reversed broadly over the continental slope. Near-bottom salinities in 2018–2019 were higher than during 2011–2015. Along 170° E, the salinity increase between 2011 and 2018 was greater than that observed in the west. The layer thickness of the densest AABW increased during the 2010s, suggesting that the Ross Sea Bottom Water intensification was a major source of the salinity increase. Freshwater content on the continental slope decreased at a rate of 58 ± 37 Gt/a in the near-bottom layer. The decadal change is very likely due to changes in Ross Sea shelf water attributable to a decrease in meltwater from West Antarctic ice shelves for the corresponding period.

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Section: Methodsmentioning

confidence: 84%

Reversal of freshening trend of Antarctic Bottom Water in the Australian-Antarctic Basin during 2010s

Aoki

Yamazaki

Hirano

et al. 2020

Sci Rep

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“…Above this (region C), salinity is substantially greater at HWD2, so that the apparent midcolumn rate of freshening is reduced within the cavity relative to Ross Sea conditions. This may relate to the recent apparent reversal in salinity trend in the region (48). The distinct S p -θ 0 signature of the benthic boundary layer (region A) at HWD2 was not observed at J9 or at Coulman High, implying that the identifiable inflow is limited in spatial extent.…”

Section: Has the Cavity Water Column Changed Since 1977?mentioning

confidence: 92%

Ocean mixing and heat transport processes observed under the Ross Ice Shelf control its basal melting

Stevens

Hulbe

Brewer

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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The stability of large Antarctic ice shelves has important implications for global sea level, sea ice area, and ocean circulation. A significant proportion of ice mass loss from these ice shelves is through ocean-driven melting which is controlled by largely unobserved oceanic thermodynamic and circulatory processes in the cavity beneath the ice shelf. Here we use direct measurements to provide evidence of the changing water column structure in the cavity beneath the Ross Ice Shelf, the planet’s largest ice shelf by area. The cavity water column data exhibit both basal and benthic boundary layers, along with evidence of tidally modulated and diffusively convecting internal mixing processes. A region of thermohaline interleaving in the upper–middle water column indicates elevated diffusion and the potential to modify the cavity circulation. The measurements were recorded using the Aotearoa New Zealand Ross Ice Shelf Program hot water drill borehole melted in the central region of the shelf in December 2017 (HWD2), only the second borehole through the central region of the ice shelf, following J9 in 1977. These data, and comparison with the 1977 data, provide valuable insight into ice shelf cavity circulation and aid understanding of the evolution of the presently stable Ross Ice Shelf.

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“…3). This accounts for about 4 % of the sea-ice production area in the Ross Ice Shelf polynya (Cheng et al, 2017). The opening of TNBP by westerly winds that blow from across the NIS occurs over the span of a day (Fig.…”

Section: Tnbp Mechanical Scalesmentioning

confidence: 99%

Variability in high-salinity shelf water production in the Terra Nova Bay polynya, Antarctica

et al. 2020

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Terra Nova Bay in Antarctica is a formation region for high-salinity shelf water (HSSW), which is a major source of Antarctic Bottom Water. Here, we analyze spatiotemporal salinity variability in Terra Nova Bay with implications for the local HSSW production. The salinity variations in the Drygalski Basin and eastern Terra Nova Bay near Crary Bank in the Ross Sea were investigated by analyzing hydrographic data from instrumented moorings, vessel-based profiles, and available wind and sea-ice products. Near-bed salinity in the eastern Terra Nova Bay ( ∼ 660 m) and Drygalski Basin (∼ 1200 m) increases each year beginning in September. Significant salinity increases (> 0.04) were observed in 2016 and 2017, which is likely related to active HSSW formation. According to velocity data at identical depths, the salinity increase from September was primarily due to advection of the HSSW originating from the coastal region of the Nansen Ice Shelf. In addition, we show that HSSW can also be formed locally in the upper water column (< 300 m) of the eastern Terra Nova Bay through convection supplied by brine from the surface, which is related to polynya development via winds and ice freezing. While the general consensus is that the salinity of the HSSW was decreasing from 1995 to the late 2000s in the region, the salinity has been increasing since 2016. In 2018, it returned to values comparable to those in the early 2000s.

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Rebound of shelf water salinity in the Ross Sea

Cited by 55 publications

References 32 publications

Reversal of freshening trend of Antarctic Bottom Water in the Australian-Antarctic Basin during 2010s

Reversal of freshening trend of Antarctic Bottom Water in the Australian-Antarctic Basin during 2010s

Ocean mixing and heat transport processes observed under the Ross Ice Shelf control its basal melting

Variability in high-salinity shelf water production in the Terra Nova Bay polynya, Antarctica

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