Abstract
The Mertz Glacier Polynya off George V Land, East Antarctica, is a source of Adélie Land Bottom Water, which contributes up to ~25% of the Antarctic Bottom Water. This major polynya is closely linked to the presence of the Mertz Glacier Tongue that traps pack ice upstream. In 2010, the Mertz Glacier calved a massive iceberg, deeply impacting local sea ice conditions and dense shelf water formation. Here we provide the first detailed 250-year long reconstruction of local sea ice and bottom water conditions. Spectral analysis of the data sets reveals large and abrupt changes in sea surface and bottom water conditions with a ~70-year cyclicity, associated with the Mertz Glacier Tongue calving and regrowth dynamics. Geological data and atmospheric reanalysis, however, suggest that sea ice conditions in the polynya were also very sensitive to changes in surface winds in relation to the recent intensification of the Southern Annular Mode.
Highlights
The Mertz Glacier Polynya off George V Land, East Antarctica, is a source of Adelie Land Bottom Water, which contributes up to B25% of the Antarctic Bottom Water
Assuming that greater deep-reaching convection is associated with intensified bottom currents, the high Zirconium versus Rubidium (Zr/Rb) ratios (Fig. 2) recorded during periods of well-developed MGP suggest enhanced bottom currents favouring a coarse sedimentation at the core location
A reduction of the MGP area and sea ice production coincided with a weaker bottom circulation, as revealed by the presence of finer sediments
Summary
The Mertz Glacier Polynya off George V Land, East Antarctica, is a source of Adelie Land Bottom Water, which contributes up to B25% of the Antarctic Bottom Water. In 2010, the Mertz Glacier calved a massive iceberg, deeply impacting local sea ice conditions and dense shelf water formation. While the 13 major Antarctic coastal polynyas only represent B1% of the maximum ice area, they are responsible for the production of 10% of the Southern Ocean sea ice[3] It 140°E. has been shown that B25% of the AABW is sourced from the export of Adelie Land Bottom Water (ALBW) produced in the George V Land polynyas[2,6]. Mooring observations and satellite data showed that oceanic and sea ice conditions (Fig. 1e) over the CB and MGP areas have experienced similar and synchronous pre- and postcalving changes over the recent years[9]. These sporadic observations are insufficient to reconstruct past MGT dynamics with a high level of confidence
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