Poleward eddy-induced warm water transport across a shelf break off Totten Ice Shelf, East Antarctica

Hirano, Daisuke; Mizobata, Kohei; Sasaki, Hidetada; Murase, Hiroto; Tamura, Takeshi; Aoki, Shigeru

doi:10.1038/s43247-021-00217-4

Cited by 27 publications

(22 citation statements)

References 34 publications

(65 reference statements)

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“…8) (Greenbaum et al, 2015;Rintoul et al, 2016;Silvano et al, 2017). This poleward transport is possibly caused by a combination of wind forcing, decreased polynya activity and cyclonic eddies (Greene et al, 2017;Gwyther et al, 2014;Hirano et al, 2021). Similarly, the ocean heat transfer by mCDW to the MUIS depends on the nearby Dalton polynya activity and the flow route of Antarctic Slope Current (ASC) across the Dalton Rise (Gwyther et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

“…1) (Silvano et al, 2017). Driven by nearby Dalton polynya activity, wind forcing or cyclonic eddies, the relatively warm salty water can encroach the sub-ice-shelf cavity through a deep trough (Nitsche et al, 2017), supplying sufficient heat to induce basal melting of the ice shelves (Greenbaum et al, 2015;Greene et al, 2017;Gwyther et al, 2014;Hirano et al, 2021;Rintoul et al, 2016). As a result, the TGIS and MUIS have been undergoing high basal melting compared with other regions in East Antarctica (Adusumilli et al, 2020;Depoorter et al, 2013;Pritchard et al, 2012), including at their deep GLs (Chuter and Bamber, 2015;.…”

Section: Introductionmentioning

confidence: 99%

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Grounding line retreat and tide-modulated ocean channels at Moscow University and Totten Glacier ice shelves, East Antarctica

Dawson

Chuter

et al. 2022

Preprint

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Abstract. The Totten and Moscow University glaciers, located in East Antarctica, contain 5.1 m sea-level equivalent of ice and have been losing mass over recent decades. Using ICESat-2 laser altimetry repeat track analysis and satellite radar interferometry from Sentinel-1a/b SAR images, we mapped the grounding line locations of these two glaciers between 2017 and 2021. We detected pervasive grounding line retreat along the ice plains at the glacier central trunk of Totten Glacier Ice Shelf (TGIS) and Moscow University Ice Shelf (MUIS), where the GL retreated 3.51 ± 0.49 km and 13.85 ± 0.08 km during 1996–2020, respectively. Using CryoSat-2 radar altimetry, we found that the observed grounding line retreats are coincident with high thinning rates and high ice velocities, indicating a mass loss pattern dominated by ice dynamics. We also identified two tide-modulated ocean channels on the Totten eastern ice shelf and the Moscow University western ice shelf, where the ocean channel widths are highly correlated with the tidal range. The opening of the Moscow University western ice shelf channel connects the two previously separated TGIS and MUIS systems, which might open a pathway for the warm modified circumpolar deep water entering the main MUIS cavity and facilitate further grounding line retreat.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Grounding line retreat and tide-modulated ocean channels at Moscow University and Totten Glacier ice shelves, East Antarctica

Dawson

Chuter

et al. 2022

Preprint

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“…Tidal and eddy processes are important in transporting heat towards the continental shelves, which then may further intrude into the ice shelf cavities and hence drive basal melting (Klinck and Dinniman, 2010;Couto et al, 2017;Padman et al, 2018). Recent observational studies have proved that warm (temperature > 0 °C) and saline (salinity > 34.7 g Kg -1 ) mCDW is a key factor that transports heat across the shelf break via semi-permanent cyclonic eddies (Mizobata et al, 2020;Hirano et al, 2021). During this process, warm water could be transported through bottom layers into the cavities along deep troughs at the ice shelf front and cause strong basal melting of TIS and MUIS (Nitsche et al, 2017;Silvano et al, 2017;Hirano et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Recent observational studies have proved that warm (temperature > 0 °C) and saline (salinity > 34.7 g Kg -1 ) mCDW is a key factor that transports heat across the shelf break via semi-permanent cyclonic eddies (Mizobata et al, 2020;Hirano et al, 2021). During this process, warm water could be transported through bottom layers into the cavities along deep troughs at the ice shelf front and cause strong basal melting of TIS and MUIS (Nitsche et al, 2017;Silvano et al, 2017;Hirano et al, 2021). To resolve the poleward eddy transport onto the continental shelf and the ice shelf cavities, horizontal grid spacings of less than 2 km are thought to be required (Hattermann et al, 2014;Graham et al, 2016;Mack et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Eddy and tidal driven basal melting of the Totten and Moscow University ice shelves

et al. 2023

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The mass loss from the neighboring Totten and Moscow University ice shelves is accelerating and may raise global sea levels in coming centuries. Totten Glacier is mostly based on bedrock below sea level, and so is vulnerable to warm water intrusion reducing its ice shelf buttressing. The mechanisms driving the ocean forced sub-ice-shelf melting remains to be further explored. In this study, we simulate oceanic-driven ice shelf melting of the Totten (TIS) and Moscow University ice shelves (MUIS) using a high spatiotemporal resolution model that resolves both eddy and tidal processes. We selected the year 2014 as representative of the period 1992 to 2017 to investigate how basal melting varies on spatial and temporal scales. We apply the wavelet coherence method to investigate the interactions between the two ice shelves in time-frequency space and hence estimate the contributions from tidal (<1.5 days) and eddy (2-35 days) components of the ocean heat transport to the basal melting of each ice shelf. In our simulation, the 2014 mean basal melt rate for TIS is 6.7 m yr-1 (42 Gt yr-1) and 9.7 m yr-1 (52 Gt yr-1) for MUIS. We find high wavelet coherence in the eddy dominated frequency band between the two ice shelves over almost the whole year. The wavelet coherence along five transects across the ice shelves suggests that TIS basal melting is dominated by eddy processes, while MUIS basal melting is dominated by tidal processes. The eddy-dominated basal melt for TIS is probably due to the large and convoluted bathymetric gradients beneath the ice shelf, weakening higher frequency tidal mode transport. This illustrates the key role of accurate bathymetric data plays in simulating on-going and future evolution of these important ice shelves.

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“…In reality, the pressure gradient associated with topographic features generates standing eddies and meanders, facilitating meridional water exchange (e.g., Hogg & Blundell, 2006). Topography‐controlled geostrophic flows can transport CDW poleward in the continental margin (Hirano et al., 2021; Morrison et al., 2020). However, the steep barotropic potential vorticity (PV) gradient in the upper continental slope (shallower than ∼3,000 m isobaths) is unlikely to allow the presence of cross‐slope mean flow, and thus eddy diffusion and tidal mixing might be essential to determine the onshore CDW flux near the shelf break (Stewart et al., 2018; Yamazaki et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Diffusion of Circumpolar Deep Water Towards Antarctica

2023

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Throughout the Antarctic Circumpolar Current (ACC), mesoscale eddies transport water masses across time-mean streamlines, comprising the adiabatic pathway of the global meridional overturning circulation (Cessi, 2019;Marshall & Radko, 2003). Isopycnal eddy diffusion is fundamental for the poleward heat flux across the ACC because bottom-enhanced diapycnal mixing (Kunze et al., 2006) and surface water transformation (Abernathey et al., 2016) are unlikely to penetrate the intermediate and deep layers. Recent observations have indicated that mesoscale eddies play a key role in bridging the Antarctic meridional overturning from deep ocean basins to continental shelves (e.g., Mckee et al., 2019;Yamazaki et al., 2021), but its regime transition and transporting flux from the ACC to the Antarctic Slope Current (ASC) largely remains unknown from an observational standpoint (Thompson et al., 2018).Circumpolar Deep Water (CDW), the primary source of heat and salt for the Antarctic coasts, is transported across the ASC predominantly by mesoscale eddies in the absence of large-scale zonal pressure gradients (Stewart &

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Poleward eddy-induced warm water transport across a shelf break off Totten Ice Shelf, East Antarctica

Cited by 27 publications

References 34 publications

Grounding line retreat and tide-modulated ocean channels at Moscow University and Totten Glacier ice shelves, East Antarctica

Grounding line retreat and tide-modulated ocean channels at Moscow University and Totten Glacier ice shelves, East Antarctica

Eddy and tidal driven basal melting of the Totten and Moscow University ice shelves

Diffusion of Circumpolar Deep Water Towards Antarctica

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