Abstract
Abstract. Current glacier melt rates in West Antarctica substantially exceed those around the East Antarctic margin. The exception is Wilkes Land, where for example Totten Glacier underwent significant retreat between 2000 and 2012, underlining its sensitivity to climate change. This process is strongly influenced by ocean dynamics, which in turn changes in accordance with the evolution of the ice caps. Here, we present new oceanographic data (temperature, salinity, and dissolved oxygen) collected during austral summer 2017 offshore the Sabrina Coast (East Antarctica) from the continental shelf break to ca 3000 m depth. This area is characterized by very few oceanographic in situ observations. The main water masses of the study area, identified by analysing thermohaline properties, are the Antarctic Surface Water with potential temperature θ>-1.5 ∘C and salinity S<34.2 (σθ<27.55 kg m−3), the Winter Water with -1.92<θ<-1.75 ∘C and 34.0<S<34.5 (potential density, 27.55<σθ<27.7 kg m−3), the modified Circumpolar Deep Water with θ>0 ∘C and S>34.5 (σθ>27.7 kg m−3), and Antarctic Bottom Water with -0.50<θ<0 ∘C and 34.63<S<34.67 (27.83<σθ<27.85; neutral density γn>28.30 kg m−3). The latter is a mixture of dense waters from the Ross Sea and Adélie Land continental shelves. Such waters are influenced by the mixing processes they undergo as they move westward along the Antarctic margin, also interacting with the warmer Circumpolar Deep Water. The spatial distribution of water masses offshore the Sabrina Coast also appears to be strongly linked with the complex morpho-bathymetry of the slope and rise area, supporting the hypothesis that downslope processes contribute to shaping the architecture of the distal portion of the continental margin. Oceanographic data presented here can be downloaded from https://doi.org/10.25919/yyex-t381 (CSIRO; Van Graas, 2021).
Highlights
Polar regions are key components of Earth’s climate system and are sensitive to ongoing climate change effects induced by anthropogenic pressures
The Totten Glacier is an exception, since the melting rates of this glacier and of the nearby Moscow University ice shelf (MUIS) are among the fastest in the East Antarctic ice sheets (Khazendar et al, 2013; Li et al, 2015; Mohajerani et al, 2018): the glacier draining into MUIS shows a 3 Gt yr−1 loss in 1979–2003 and a 0.3 Gt yr−1 gain in 2017, whereas Totten Glacier loss has increased through time from 5.7 Gt yr−1 in 1979–2003 to 7.3 Gt yr−1 in 2003– 2017 (Rignot et al, 2019)
This paper aims at describing the thermohaline structures from the continental shelf break to about 3000 m depth identified in the offshore area along the Sabrina Coast, by analysing physical oceanographic data collected in 2017 during a multidisciplinary Antarctic expedition
Summary
Polar regions are key components of Earth’s climate system and are sensitive to ongoing climate change effects induced by anthropogenic pressures. The Totten Glacier is an exception, since the melting rates of this glacier and of the nearby Moscow University ice shelf (MUIS) are among the fastest in the East Antarctic ice sheets (Khazendar et al, 2013; Li et al, 2015; Mohajerani et al, 2018): the glacier draining into MUIS shows a 3 Gt yr−1 loss in 1979–2003 and a 0.3 Gt yr−1 gain in 2017, whereas Totten Glacier loss has increased through time from 5.7 Gt yr−1 in 1979–2003 to 7.3 Gt yr−1 in 2003– 2017 (Rignot et al, 2019) These changes are enhanced by incursions of relatively warm modified Circumpolar Deep Water (mCDW) to the continental shelf and to the glacier grounding line, favoured by wind stress, local eddies, and bathymetric constraints (Rintoul et al, 2016; Silvano et al, 2016, 2017; Nitsche et al, 2017; Greene et al, 2017; Hirano et al, 2021). This paper aims at describing the thermohaline structures from the continental shelf break to about 3000 m depth identified in the offshore area along the Sabrina Coast, by analysing physical oceanographic data collected in 2017 during a multidisciplinary Antarctic expedition (see below)
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