Formation of sea ice ponds from ice-shelf runoff, adjacent to the McMurdo Ice Shelf, Antarctica

Macdonald, Grant J.; Popović, Predrag; Mayer, D. P.

doi:10.1017/aog.2020.9

Cited by 2 publications

(2 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is important to remove the influence of different satellite imagery acquisition conditions before extracting SGL extents and depths. To do this, digital numbers were converted to top-of-atmosphere (TOA) reflectance for red and blue bands using DOS1 (dark-object subtraction) atmospheric correction (Moran et al, 1992) in QGIS and the scenespecific metadata file containing reflectance multiplicative and additive scaling factors and the solar elevation angle. This process removes the cosine effect at different solar zenith angles (due to different scene time acquisitions) and compensates for differences in solar irradiance.…”

Section: Satellite Imagery Acquisition and Processingmentioning

confidence: 99%

Distribution and seasonal evolution of supraglacial lakes on Shackleton Ice Shelf, East Antarctica

et al. 2020

View full text Add to dashboard Cite

Abstract. Supraglacial lakes (SGLs) enhance surface melting and can flex and fracture ice shelves when they grow and subsequently drain, potentially leading to ice shelf disintegration. However, the seasonal evolution of SGLs and their influence on ice shelf stability in East Antarctica remains poorly understood, despite some potentially vulnerable ice shelves having high densities of SGLs. Using optical satellite imagery, air temperature data from climate reanalysis products and surface melt predicted by a regional climate model, we present the first long-term record (2000–2020) of seasonal SGL evolution on Shackleton Ice Shelf, which is Antarctica's northernmost remaining ice shelf and buttresses Denman Glacier, a major outlet of the East Antarctic Ice Sheet. In a typical melt season, we find hundreds of SGLs with a mean area of 0.02 km2, a mean depth of 0.96 m and a mean total meltwater volume of 7.45×106 m3. At their most extensive, SGLs cover a cumulative area of 50.7 km2 and are clustered near to the grounding line, where densities approach 0.27 km2 km−2. Here, SGL development is linked to an albedo-lowering feedback associated with katabatic winds, together with the presence of blue ice and exposed rock. Although below-average seasonal (December–January–February, DJF) temperatures are associated with below-average peaks in total SGL area and volume, warmer seasonal temperatures do not necessarily result in higher SGL areas and volumes. Rather, peaks in total SGL area and volume show a much closer correspondence with short-lived high-magnitude snowmelt events. We therefore suggest seasonal lake evolution on this ice shelf is instead more sensitive to snowmelt intensity associated with katabatic-wind-driven melting. Our analysis provides important constraints on the boundary conditions of supraglacial hydrology models and numerical simulations of ice shelf stability.

show abstract

Section: Satellite Imagery Acquisition and Processingmentioning

confidence: 99%

Distribution and seasonal evolution of supraglacial lakes on Shackleton Ice Shelf, East Antarctica

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Although unlikely to have been important on the VIS, melt ponds on the adjacent sea-ice and mélange may promote their break-up by lowering their surface albedo, causing them to thin and potentially make them more prone to fracturing and breakout if they flex (Miles and others, 2017; Macdonald and others, 2020). We observed melt ponds on the MYLI between VIS and Moscow University Ice Shelf (MUIS) in January 2007 (Fig.…”

Section: Discussionmentioning

confidence: 99%

The triggers of the disaggregation of Voyeykov Ice Shelf (2007), Wilkes Land, East Antarctica, and its subsequent evolution

et al. 2021

View full text Add to dashboard Cite

The weakening and/or removal of floating ice shelves in Antarctica can induce inland ice flow acceleration. Numerical modelling suggests these processes will play an important role in Antarctica's future sea-level contribution, but our understanding of the mechanisms that lead to ice tongue/shelf collapse is incomplete and largely based on observations from the Antarctic Peninsula and West Antarctica. Here, we use remote sensing of structural glaciology and ice velocity from 2001 to 2020 and analyse potential ocean-climate forcings to identify mechanisms that triggered the rapid disintegration of ~2445 km2 of ice mélange and part of the Voyeykov Ice Shelf in Wilkes Land, East Antarctica between 27 March and 28 May 2007. Results show disaggregation was pre-conditioned by weakening of the ice tongue's structural integrity and was triggered by mélange removal driven by a regional atmospheric circulation anomaly and a less extensive latent-heat polynya. Disaggregation did not induce inland ice flow acceleration, but our observations highlight an important mechanism through which floating termini can be removed, whereby the break-out of mélange and multiyear landfast sea ice triggers disaggregation of a structurally-weak ice shelf. These observations highlight the need for numerical ice-sheet models to account for interactions between sea-ice, mélange and ice shelves.

show abstract

Formation of sea ice ponds from ice-shelf runoff, adjacent to the McMurdo Ice Shelf, Antarctica

Cited by 2 publications

References 34 publications

Distribution and seasonal evolution of supraglacial lakes on Shackleton Ice Shelf, East Antarctica

Distribution and seasonal evolution of supraglacial lakes on Shackleton Ice Shelf, East Antarctica

The triggers of the disaggregation of Voyeykov Ice Shelf (2007), Wilkes Land, East Antarctica, and its subsequent evolution

Contact Info

Product

Resources

About