Intermittent Reduction in Ocean Heat Transport Into the Getz Ice Shelf Cavity During Strong Wind Events

Steiger, Nadine; Darelius, Elin; Wåhlin, Anna; Assmann, Karen M.

doi:10.1029/2021gl093599

Cited by 4 publications

(1 citation statement)

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“…The seasonal variation observed at DIS is in contrast to seasonal variation in the deep troughs leading to Pine Island Glacier 22 and to Getz Glacier 32 , 35 , 39 , where a wintertime maximum in heat content and velocity has been observed. In contrast to the situation at Pine Island Glacier calving front 22 , where the main cause for vertical migration of the thermocline is local buoyancy flux, short-term variability of heat transport was here caused by local changing stress at the ocean surface due to wind and sea ice conditions.…”

Section: Discussionmentioning

confidence: 58%

Seasonal variability of ocean circulation near the Dotson Ice Shelf, Antarctica

et al. 2022

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Recent rapid thinning of West Antarctic ice shelves are believed to be caused by intrusions of warm deep water that induce basal melting and seaward meltwater export. This study uses data from three bottom-mounted mooring arrays to show seasonal variability and local forcing for the currents moving into and out of the Dotson ice shelf cavity. A southward flow of warm, salty water had maximum current velocities along the eastern channel slope, while northward outflows of freshened ice shelf meltwater spread at intermediate depth above the western slope. The inflow correlated with the local ocean surface stress curl. At the western slope, meltwater outflows followed the warm influx along the eastern slope with a ~2–3 month delay. Ocean circulation near Dotson Ice Shelf, affected by sea ice distribution and wind, appears to significantly control the inflow of warm water and subsequent ice shelf melting on seasonal time-scales.

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Section: Discussionmentioning

confidence: 58%

Seasonal variability of ocean circulation near the Dotson Ice Shelf, Antarctica

et al. 2022

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The Dynamics of a Barotropic Current Impinging on an Ice Front

Steiger

Darelius

Kimura

et al. 2022

Journal of Physical Oceanography

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The vertical front of ice shelves represents a topographic barrier for barotropic currents that transport a considerable amount of heat towards the ice shelves. The blocking effect of the ice front on barotropic currents has recently been observed to substantially reduce the heat transport into the cavity beneath the Getz Ice Shelf. We use an idealized numerical model to study the vorticity dynamics of an externally forced barotropic current at an ice front and the impact of ice shelf thickness, ice front steepness, and ocean stratification on the volume flux entering the cavity. Our simulations show that thicker ice shelves block a larger volume of the barotropic flow, in agreement with geostrophic theory. However, geostrophy breaks locally at the ice front, where relative vorticity and friction become essential for the flow to cross the discontinuity in water column thickness. The flow entering the cavity accelerates and induces high basal melt rates in the frontal region. Tilting the ice front, as undertaken in sigma-coordinate models, reduces this acceleration as the flow is more geostrophic. Viscous processes—typically exaggerated in low-resolution models—break the potential vorticity constraint and bring the flow deeper into the ice shelf cavity. The externally forced barotropic current can only enter the cavity if the stratification is weak, as strong vertical velocities are needed at the ice front to squeeze the water column beneath the ice shelf. If the stratification is strong, vertical velocities are suppressed and the barotropic flow is almost entirely blocked by the ice front.

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Assessment of water mass distribution and intrusions of circumpolar deep water in the Amundsen Sea based on the ocean reanalysis product FOAM-GLOSEA5v13

Li,

Wang,

Zhou

2024

Front. Mar. Sci.

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The Amundsen Sea of West Antarctica is one of the regions of particularly interest to the oceanography community due to accelerated basal melting of its ice shelves. Quantitative estimates of the composition of water masses and their sources are essential for understanding the heat and salt budgets and the stability of ice shelves in this region. In this study, the water mass distributions on the Amundsen Sea continental shelf are estimated based on FOAM-GLOSEA5v13, a global oceanographic reanalysis product, using a modified statistical based optimal water mass analysis method. The reanalysis product effectively captures the signal of primary water masses, including the Winter Water (WW) and the Circumpolar Deep Water (CDW) below the Antarctic Summer Surface Water (SSW). The horizontal and vertical distributions and temporal evolution of three water mass endmembers (WW, CDW and DSW) and their mixing ratios are calculated, based on which an intrusion location detection method was established. Using the reanalysis product and intrusion detection method, all potential CDW intrusion sites along the shelf break are identified. Based on the reanalysis product, an intrusion site over the shelf break, away from major deep troughs was captured and confirmed by numerical particle tracking experiments.

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Intermittent Reduction in Ocean Heat Transport Into the Getz Ice Shelf Cavity During Strong Wind Events

Abstract: Increased oceanic heat transport toward the ice shelves has been the primary driver of ice-shelf thinning in the Amundsen Sea sector of West Antarctica during the last decades (

Cited by 4 publications

References 65 publications

Seasonal variability of ocean circulation near the Dotson Ice Shelf, Antarctica

Seasonal variability of ocean circulation near the Dotson Ice Shelf, Antarctica

The Dynamics of a Barotropic Current Impinging on an Ice Front

Assessment of water mass distribution and intrusions of circumpolar deep water in the Amundsen Sea based on the ocean reanalysis product FOAM-GLOSEA5v13

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