Glacier tongue calving reduced dense water formation and enhanced carbon uptake

[1] Dense shelf water formed in the Mertz Polynya supplies the lower limb of the global overturning circulation, ventilating the abyssal Indian and Pacific Oceans. Calving of the Mertz Glacier Tongue (MGT) in February 2010 altered the regional distribution of ice and reduced the size and activity of...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Shadwick, EH, Rintoul, SR, Tilbrook, BD, Williams, GD, Young, NW, Fraser, AD, Marchant, H, Smith, J, Tamura, T
Format: Article in Journal/Newspaper
Language:English
Published: Amer Geophysical Union 2013
Subjects:
Earth Sciences
Oceanography
Physical Oceanography
Antarctic
Indian
Mertz Glacier
Mertz Glacier Tongue
Pacific
The Antarctic
Antarc*
Iceberg*
Sea ice
Online Access:https://doi.org/10.1002/grl.50178
http://ecite.utas.edu.au/83966
Description
Summary:[1] Dense shelf water formed in the Mertz Polynya supplies the lower limb of the global overturning circulation, ventilating the abyssal Indian and Pacific Oceans. Calving of the Mertz Glacier Tongue (MGT) in February 2010 altered the regional distribution of ice and reduced the size and activity of the polynya. The salinity and density of dense shelf water declined abruptly after calving, consistent with a reduction of sea ice formation in the polynya. Breakout and melt of thick multiyear sea ice released by the movement of iceberg B9B and the MGT freshened near-surface waters. The input of meltwater likely enhanced the availability of light and iron, supporting a diatom bloom that doubled carbon uptake relative to precalving conditions. The enhanced biological carbon drawdown increased the carbonate saturation state, outweighing dilution by meltwater input. These observations highlight the sensitivity of dense water formation, biological productivity, and carbon export to changes in the Antarctic icescape.

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