Greenland ice sheet mass balance assessed by PROMICE (1995–2015)

Colgan, William; Mankoff, K. D.; Kjeldsen, Kristian K.; Bjørk, Anders A.; Box, Jason E.; Simonsen, Sebastian B.; Sørensen, Louise Sandberg; Khan, Shfaqat Abbas; Solgaard, Anne; Forsberg, R.; Skourup, Henriette; Stenseng, Lars; Kristensen, Steen Savstrup; Hvidegaard, Sine Munk; Citterio, Michele; Karlsson, Nanna B.; Fettweis, Xavier; Ahlstrøm, Andreas P.; Andersen, S. B.; As, Dirk van; Fausto, Robert S.

doi:10.34194/geusb-201943-02-01

Cited by 13 publications

(28 citation statements)

References 12 publications

(32 reference statements)

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“…(4) Colgan‐IOMB, the annual mass‐balance record from 1995 to 2020 based on Colgan et al. (2019). (5) Mouginot‐IOMB, the annual mass‐balance record from 1972 to 2018 based on Mouginot et al.…”

Section: Methodsmentioning

confidence: 99%

“…The long 28-year time-series of radar-VMB for the GrIS (cyan). The green curve shows the 2-year temporal-derivative of the GMB record, the red curve is the long time series IO-based mass balance estimate fromMouginot et al (2019), and the magenta is the IO-based mass balance estimate fromColgan et al (2019). The lower left inset shows the 1992-2020 sea-level rise contribution as derived for the radar-VMB, Mouginot-MB, Colgan-MB and GRACE-GMB, all given in respect to January 2003.…”

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confidence: 99%

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Greenland Ice Sheet Mass Balance (1992–2020) From Calibrated Radar Altimetry

Simonsen

Barletta

Colgan

et al. 2021

Geophysical Research Letters

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We present the first 1992–2020 record of Greenland Ice Sheet (GrIS) mass balance derived from multisatellite Ku‐band altimetry. We employ an empirical approach as an alternative detailed to radar‐propagation modeling, and instead convert elevation changes observed by radar altimetry into mass changes using spatiotemporal calibration fields. This calibration field is derived from a machine learning approach that optimizes the prediction of a previously published mass balance field as a function of ice sheet variables. Our mass balance record shows a GrIS contribution of 12.1 ± 2.3 mm sea‐level equivalent since 1992, with more than 80% of this contribution occurring after 2003. Our record also suggests that the 2017 hydrological year is the first year in the 21st century which, within uncertainties, the GrIS was in balance. Overall, the 28‐year radar‐derived mass balance record we present highlights the potential of the method to provide operational mass balance estimates derived from multisatellite Ku‐band altimetry.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Greenland Ice Sheet Mass Balance (1992–2020) From Calibrated Radar Altimetry

Simonsen

Barletta

Colgan

et al. 2021

Geophysical Research Letters

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“…Icebergs are a major component of Greenland's glacial fjords. Frontal ablation (iceberg calving plus submarine melting of glacier termini) at tidewater glaciers represents~30-50% of the freshwater export from the ice sheet into the ocean, of which calving of icebergs is the larger component 28 . Icebergs melt partially or entirely whilst transiting glacial fjords [29][30][31] , thereby providing a heat sink and fresh water source that is distributed horizontally and vertically throughout the fjord.…”

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confidence: 99%

Iceberg melting substantially modifies oceanic heat flux towards a major Greenlandic tidewater glacier

et al. 2020

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Fjord dynamics influence oceanic heat flux to the Greenland ice sheet. Submarine iceberg melting releases large volumes of freshwater within Greenland’s fjords, yet its impact on fjord dynamics remains unclear. We modify an ocean model to simulate submarine iceberg melting in Sermilik Fjord, east Greenland. Here we find that submarine iceberg melting cools and freshens the fjord by up to ~5 °C and 0.7 psu in the upper 100-200 m. The release of freshwater from icebergs drives an overturning circulation, resulting in a ~10% increase in net up-fjord heat flux. In addition, we find that submarine iceberg melting accounts for over 95% of heat used for ice melt in Sermilik Fjord. Our results highlight the substantial impact that icebergs have on the dynamics of a major Greenlandic fjord, demonstrating the importance of including related processes in studies that seek to quantify interactions between the ice sheet and the ocean.

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“…Moreover, comparison between modeled SMB from MAR at resolutions between 15 and 50 km can result in ice‐sheet‐wide SMB differences of 70 Gt yr –1 when computed on masks specific to the spatial resolution of each run, while SMB differences decrease to 23 Gt yr –1 when computing on a mask common to all spatial resolutions (Franco et al., 2012). Moreover, employing a 500 m version of the PROMICE ice mask with a more extensive ablation area decreased ice‐sheet integrated SMB by ∼30 Gt yr –1 relative to using the native 25 km MAR ice mask (Colgan et al., 2019), suggesting that SMB variability is rooted in the ablation area variability. Increased ice‐sheet‐wide agreement between four SMB‐models was also found by Vernon and colleagues, when assessed over a common mask, although regionally there was less agreement, which suggest that spatial differences improve the integrated SMB‐estimates (Vernon et al., 2013).…”

Section: Resultsmentioning

confidence: 99%

“…Ice mask area influences both the input (SMB) and the output (ice discharge) by determining the apparent ablation area. Ice discharge is sensitive to ablation area through the SMB corrections applied to convert ice flow across upstream flux gates into ice flow across the downstream grounding line (Colgan et al., 2019; Rignot & Kanagaratnam, 2006). Even for land‐terminating glaciers, ice marginal retreat becomes important if accurate and updated ice masks are not incorporated.…”

Section: Resultsmentioning

confidence: 99%

Time‐Varying Ice Sheet Mask: Implications on Ice‐Sheet Mass Balance and Crustal Uplift

et al. 2020

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A standard approach for these reconciliations is to use a common mask for the area of the ice sheet, as well as a common period over which to assess mass change (e.g., Vernon et al., 2013). These time-space standardizations aim to ensure that discrepancies between the individual, and reconciled estimates are due to methodology, rather than differences in spatiotemporal sampling. For example, once interpolated on to a common ice mask, variations between four surface mass-balance models decreased and produced a reasonable agreement (Vernon et al., 2013). This improvement was attributed primarily to a decrease in the peripheral ablation area, where disagreements were largest, while leaving the interior accumulation area the same size. However, many studies have also reported widespread retreat of the Greenland Ice Sheet margin, especially at marine-terminating outlet glaciers in northwestern Greenland (

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Greenland ice sheet mass balance assessed by PROMICE (1995–2015)

Cited by 13 publications

References 12 publications

Greenland Ice Sheet Mass Balance (1992–2020) From Calibrated Radar Altimetry

Greenland Ice Sheet Mass Balance (1992–2020) From Calibrated Radar Altimetry

Iceberg melting substantially modifies oceanic heat flux towards a major Greenlandic tidewater glacier

Time‐Varying Ice Sheet Mask: Implications on Ice‐Sheet Mass Balance and Crustal Uplift

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