The influence of föhn winds on annual and seasonal surface melt on the Larsen C Ice Shelf, Antarctica

Turton, Jenny; Kirchgaessner, Amélie; Ross, Andrew; King, John C.; Munneke, Peter Kuipers

doi:10.5194/tc-14-4165-2020

Cited by 20 publications

(27 citation statements)

References 34 publications

(94 reference statements)

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“…On the other hand, wind conditions are a known driver for supraglacial lake occurrence on the API with previous studies reporting of warm air temperatures over George VI Ice Shelf being promoted by sensible heat transport with warm north-westerly and north-easterly winds as well as a shift towards more frequent northeasterlies (Banwell et al, 2021). Moreover, foehn winds are known to influence surface melting on the north-eastern API (Cape et al, 2015;Datta et al, 2019;Luckman et al, 2014;Turton et al, 2020) and can equally be observed on the western API with (north-)easterly prevailing wind direction (Laffin et al, 2021). This suggests the occurrence of both, foehn conditions and sensible heat transport on the API.…”

Section: Antarctic Peninsula Ice Shelvesmentioning

confidence: 62%

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Seasonal evolution of Antarctic supraglacial lakes in 2015–2021 and links to environmental controls

Dirscherl

Dietz

Kuenzer

2021

Preprint

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Abstract. Supraglacial meltwater accumulation on ice shelves may have important implications for future sea-level-rise. Despite recent progress in the understanding of Antarctic surface hydrology, potential influences on ice shelf stability as well as links to environmental drivers remain poorly constrained. In this study, we employ state-of-the-art machine learning on Sentinel-1 Synthetic Aperture Radar (SAR) and optical Sentinel-2 satellite imagery to provide new insight into the inter-annual and intra-annual evolution of surface hydrological features across six major Antarctic Peninsula and East Antarctic ice shelves. For the first time, we produce a record of supraglacial lake extent dynamics for the period 2015–2021 at unprecedented 10 m spatial resolution and bi-weekly temporal scale. Through synergetic use of optical and SAR data, we obtain a more complete mapping record enabling the delineation of also buried lakes. Our results for Antarctic Peninsula ice shelves reveal below average meltwater ponding during most of melting seasons 2015–2018 and above average meltwater ponding throughout summer 2019–2020 and early 2020–2021. Meltwater ponding on investigated East Antarctic ice shelves was far more variable with above average lake extents during most of melting seasons 2016–2019 and below average lake extents during 2020–2021. This study is the first to investigate relationships with climate drivers both, spatially and temporally including time lag analysis. The results indicate that supraglacial lake formation in 2015–2021 is coupled to the complex interplay of varying air temperature, solar radiation, snowmelt, wind and precipitation, each at different time lags and directions and with strong local to regional discrepancies, as revealed through pixel-based correlation analysis. Southern Hemisphere atmospheric modes as well as the local glaciological setting including melt-albedo feedbacks and the firn air content were revealed to strongly influence the spatio-temporal evolution of supraglacial lakes as well as below or above average meltwater ponding despite variations in the strength of forcing. Recent increases of Antarctic Peninsula surface ponding point towards a further reduction of the firn air content implying an increased risk for ponding and hydrofracture. In addition, lateral meltwater transport was observed over both Antarctic regions with similar implications for future ice shelf stability.

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Section: Antarctic Peninsula Ice Shelvesmentioning

confidence: 62%

“…5a-f). This highlights a link with melt events potentially reflecting short-lived foehn influence (Cape et al, 2015;Turton et al, 2020).…”

Section: Antarctic Peninsula Ice Shelvesmentioning

confidence: 84%

Seasonal evolution of Antarctic supraglacial lakes in 2015–2021 and links to environmental controls

Dirscherl

Dietz

Kuenzer

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Wind conditions are a known driver for supraglacial lake occurrence on the API, with previous studies reporting that warm air temperatures over George VI Ice Shelf are promoted by sensible heat transport with warm north-westerly and north-easterly winds as well as a shift towards more frequent north-easterlies (Banwell et al, 2021). Moreover, foehn winds are known to influence surface melting on the north-eastern API (Cape et al, 2015;Datta et al, 2019;Luckman et al, 2014;Turton et al, 2020) and can equally be observed on the western API with (north-)easterly prevailing wind direction (Laffin et al, 2021). This suggests the occurrence of both foehn conditions and sensible heat transport on the API.…”

Section: Antarctic Peninsula Ice Shelvesmentioning

confidence: 97%

Seasonal evolution of Antarctic supraglacial lakes in 2015–2021 and links to environmental controls

2021

View full text Add to dashboard Cite

Abstract. Supraglacial meltwater accumulation on ice shelves may have important implications for future sea level rise. Despite recent progress in the understanding of Antarctic surface hydrology, potential influences on ice shelf stability as well as links to environmental drivers remain poorly constrained. In this study, we employ state-of-the-art machine learning on Sentinel-1 synthetic aperture radar (SAR) and optical Sentinel-2 satellite imagery to provide new insight into the inter-annual and intra-annual evolution of surface hydrological features across six major Antarctic Peninsula and East Antarctic ice shelves. For the first time, we produce a high-resolution record of supraglacial lake extent dynamics for the period 2015–2021 at unprecedented 10 m spatial resolution and bi-weekly temporal scale. Through synergetic use of optical and SAR data, we obtain a more complete mapping record also enabling the delineation of buried lakes. Our results for Antarctic Peninsula ice shelves reveal below-average meltwater ponding during most of melting seasons 2015–2018 and above-average meltwater ponding throughout summer 2019–2020 and early 2020–2021 considering years 2015–2021 as a reference period. Meltwater ponding on investigated East Antarctic ice shelves was far more variable, with above-average lake extents during most 2016–2019 melting seasons and below-average lake extents during 2020–2021, considering the reference interval 2016–2021. This study is the first to investigate relationships with climate drivers both spatially and temporally including time lag analysis. The results indicate that supraglacial lake formation in 2015–2021 is coupled to the complex interplay of local, regional and large-scale environmental drivers with similar driving factors over both ice sheet regions. In particular, varying air temperature, solar radiation and wind conditions influenced supraglacial lake formation over all six ice shelves despite strong local to regional discrepancies, as revealed through pixel-based correlation analysis. Furthermore, regional climatic conditions were shown to be influenced by Southern Hemisphere atmospheric modes showing large-scale impacts on the spatio-temporal evolution of supraglacial lakes as well as on above- or below-average meltwater ponding with respect to the period 2015–2021. Finally, the local glaciological setting, including melt–albedo feedbacks and the firn air content, was revealed to strongly influence supraglacial lake distribution. Recent increases in Antarctic Peninsula surface ponding point towards a further reduction in the firn air content, implying an increased risk for ponding and hydrofracture. In addition, lateral meltwater transport was observed over both Antarctic regions with similar implications for future ice shelf stability.

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“…When ARs make landfall perpendicular to the mountains of the AP, their large moisture transport typically engenders a large latent heat release. These are ideal conditions for foehn winds, which are commonly proposed to trigger of intense surface melt along the leeward AP ice shelves 20,21,27,[39][40][41] . However, the enhanced moisture transport also triggers melt through clouds containing anomalously high liquid and ice water content resulting in high downward longwave radiation 20 .…”

Section: Physical Particularities Of Ar Eventsmentioning

confidence: 99%

The Atmospheric River Threat to Antarctic Peninsula Ice-Shelf Stability

Wille¹,

Favier²,

Jourdain³

et al. 2021

Preprint

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The disintegration of the ice shelves along the Antarctic Peninsula have spurred much discussion on the various processes leading to their eventual dramatic collapse, but without a consensus on an atmospheric forcing that could connect these processes. Here, using an atmospheric river (AR) detection algorithm along with a regional climate model and satellite observations, we show that particularly intense ARs have a ~40% probability of inducing extreme events of temperature, surface melt, sea-ice disintegration, or large swells; all processes proven to induce ice-shelf destabilization. This was observed during the collapses of the Larsen A, B, and overall, 60% of calving events triggered by ARs from 2000-2020. The loss of the buttressing effect from these ice shelves leads to further continental ice loss and subsequent sea-level rise. Understanding how ARs connect various disparate processes cited in ice-shelf collapse theories is essential for identifying other at-risk ice shelves like the Larsen C.

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The influence of föhn winds on annual and seasonal surface melt on the Larsen C Ice Shelf, Antarctica

Cited by 20 publications

References 34 publications

Seasonal evolution of Antarctic supraglacial lakes in 2015–2021 and links to environmental controls

Seasonal evolution of Antarctic supraglacial lakes in 2015–2021 and links to environmental controls

Seasonal evolution of Antarctic supraglacial lakes in 2015–2021 and links to environmental controls

The Atmospheric River Threat to Antarctic Peninsula Ice-Shelf Stability

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