Open Access Repository

Observations of ocean-ice shelf interaction at the Totten Glacier

Downloads

Downloads per month over past year

Silvano, A ORCID: 0000-0002-6441-1496 2019 , 'Observations of ocean-ice shelf interaction at the Totten Glacier', PhD thesis, University of Tasmania.

[img]
Preview
PDF (Whole thesis)
Silvano_whole_t...pdf | Download (30MB)

| Preview

Abstract

The Antarctic Ice Sheet is the largest reservoir of glacial ice on Earth, containing the ice equivalent to 60 m of global sea level rise. Multiple observations have shown that the Antarctic Ice Sheet is losing mass at an accelerating rate, with the majority of the loss occurring in West Antarctica. This mass loss is triggered by ocean-driven melting of the ice shelves that form where the continental ice extends over the ocean. In contrast to the West Antarctic Ice Sheet, the much larger East Antarctic Ice Sheet has long been considered to be stable. However, recent studies suggest that a large part of the East Antarctic Ice Sheet is grounded well below sea level and therefore exposed to ocean heat flux. Moreover, recent satellite observations have revealed that the Totten Glacier, the largest discharger of ice in East Antarctica, has been losing mass for the past 25 years, suggesting that ocean-driven ice loss may also occur in East Antarctica.
In this thesis, the first oceanographic measurements collected near the Totten Glacier on the Sabrina Coast are used to investigate why the glacier is losing mass. Warm Modified Circumpolar Deep Water (MCDW) originating from the Southern Ocean is observed entering the cavity beneath the Totten Ice Shelf near the seafloor through a deep trough. The heat transport is sufficient to drive basal melt at a rate larger than 10 m year-1, the highest rate among the major ice shelves in East Antarctica. These observations suggest that ocean heat flux drives mass loss of the Totten Glacier, as seen in West Antarctica.
Additional oceanographic observations show that MCDW is not only found in front of the Totten Glacier, but it fills the bottom layer on most of the continental shelf of the Sabrina Coast. Dense and cold waters typical of the East Antarctic coast are absent, despite the presence of a polynya where strong surface heat loss and salt flux by sea ice formation occur every winter. A simple ocean model driven by observed forcing reveals that freshwater released by ice-shelf basal melt inhibits the formation of dense waters on the Sabrina Coast, inducing a positive feedback of warming and increased ice-shelf melting. Finally, year-round observations of ocean properties collected by icecapable profiling floats show that MCDW intrusions onto the shelf are persistent. Intrusions are warmer and thicker in autumn and early winter. A realistic ocean model shows that interaction between currents on the continental slope and a depression at the shelf break facilitates the MCDW intrusions onto the shelf. The seasonality of these currents explains the warmer and thicker intrusions in autumn and early winter.
This thesis provides the first direct evidence that the East Antarctic Ice Sheet is vulnerable to oceanic melting. Considering that the East Antarctic Ice Sheet contains a volume of ice grounded below sea level that is equivalent to 19 m of global sea level rise, the potential for ocean-driven melting to destabilize this large portion of the Antarctic Ice Sheet needs to be accounted for in assessments of future sea level rise.

Item Type: Thesis - PhD
Authors/Creators:Silvano, A
Keywords: East Antarctica, Totten Glacier, ice-ocean interaction, basal melting, sea level rise
DOI / ID Number: 10.25959/100.00031865
Copyright Information:

Copyright 2019 the author

Additional Information:

Chapter 2 appears to be the equivalent of a post-print version of an article published as: Rintoul, S. R., Silvano, A., Peña-Molino, B., van Wijk, E., Rosenberg, M., Greenbaum, J. S., Blankenship D. D., 2016. Ocean heat drives rapid basal melt of Totten Ice Shelf, Sciences advances, 2(12), 1-5. 2016 © The authors. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited. https://creativecommons.org/licenses/by-nc/4.0/

Chapter 3 appears to be the equivalent of a post-print version of an article published as: Silvano, A., Rintoul, S. R., Peña-Molino, B., Williams, G. D., 2017. Distribution of water masses and meltwater on the continental shelf near the Totten Moscow University ice shelves, Journal of geophysical research. Oceans, 122(3), 2050-2068. An edited version of this paper was published by AGU. Copyright 2017 American Geophysical Union

Chapter 4 appears to be the equivalent of a post-print version of an article published as: Silvano, A., Rintoul, S. R., Herraiz-Borreguero, L., 2016. Ocean-ice shelf interaction in East Antarctica, Oceanography, 29(4), 130–143

Chapter 5 appears to be the equivalent of a post-print version of an article published as: Silvano, A., Rintoul, S. R., Peña-Molino, B., Hobbs, W. R., van Wijk, E., Aoki, S., Tamura, T., Williams, G. D., 2018. Freshening by glacial meltwater enhances melting of ice shelves and reduces formation of Antarctic bottom water, Sciences advances, 4(4), 1-11. 2018 © The authors. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited. https://creativecommons.org/licenses/by-nc/4.0/

Chapter 6 appears to be the equivalent of a post-print version of an article published as: Silvano, A., Rintoul, S. R., Kusahara, K., Peña-Molino, B., van Wijk, E., Gwyther, D. E. Williams, G. D., 2019. Seasonality of warm water intrusions onto the continental shelf near the Totten Glacier, Journal of geophysical research. Oceans, 124(6), 4272-4289. An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union

Related URLs:
Item Statistics: View statistics for this item

Actions (login required)

Item Control Page Item Control Page
TOP