Darkening of the Greenland ice sheet due to the melt albedo feedback observed at PROMICE weather stations

As, Dirk van; Fausto, Robert S.; Colgan, William; Box, Jason E.; Ahlstrøm, Andreas P.; Andersen, S. B.; Andersen, M.; Charalampidis, Charalampos; Citterio, Michele; Edelvang, Karen; Jensen, Trine S.; Larsen, Signe Hillerup; Machguth, Horst; Nielsen, Søren Bo; Veicherts, M.; Weidick, A

doi:10.34194/geusb.v28.4728

Cited by 22 publications

(23 citation statements)

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“…Here, we present firn temperatures from the KAN_U automatic weather station (AWS), which is located at 67°0′N and 47°1′W, at 1840 m a.s.l. (Van As and others, 2013, 2014; Figs 1 and 2). These measurements cover the period from 4 April 2009 until 22 September 2013.…”

Section: Introductionmentioning

confidence: 70%

Thermal tracing of retained meltwater in the lower accumulation area of the Southwestern Greenland ice sheet

Charalampidis

As²,

Colgan

et al. 2016

Ann. Glaciol.

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ABSTRACT. We present in situ firn temperatures from the extreme 2012 melt season in the southwestern lower accumulation area of the Greenland ice sheet. The upper 2.5 m of snow and firn was temperate during the melt season, when vertical meltwater percolation was inefficient due to a ∼5.5 m thick ice layer underlying the temperate firn. Meltwater percolation and refreezing beneath 2.5 m depth only occurred after the melt season. Deviations from temperatures predicted by pure conductivity suggest that meltwater refroze in discrete bands at depths of 2.0-2.5, 5.0-6.0 and 8.0-9.0 m. While we find no indication of meltwater percolation below 9 m depth or complete filling of pore volume above, firn at 10 and 15 m depth was respectively 4.2-4.5°C and 1.7°C higher than in a conductivity-only simulation. Even though meltwater percolation in 2012 was inefficient, firn between 2 and 15 m depth the following winter was on average 4.7°C warmer due to meltwater refreezing. Our observations also suggest that the 2012 firn conditions were preconditioned by two warm summers and ice layer formation in 2010 and 2011. Overall, firn temperatures during the years 2009-13 increased by 0.6°C.

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Section: Introductionmentioning

confidence: 70%

Thermal tracing of retained meltwater in the lower accumulation area of the Southwestern Greenland ice sheet

Charalampidis

As²,

Colgan

et al. 2016

Ann. Glaciol.

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“…These studies commonly express the melt-albedo feedback in terms of air/water temperature sensitivity. Our aim is to quantify the impact on the melt rate of the darkening but not the disappearance of snow, a process addressed by far fewer studies (Box et al, 2012;Van As et al, 2013). To that end, we implement a snow albedo parameterization (Gardner and Sharp, 2010;Kuipers Munneke et al, 2011b) in an SEB model, which is then calibrated using observations and used to study the sensitivity of melt rates to snow properties that influence snow albedo.…”

Section: Introductionmentioning

confidence: 99%

Quantifying the snowmelt-albedo feedback at Neumayer Station, East Antarctica

Jakobs¹,

Reijmer²,

Munneke³

et al. 2018

Preprint

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Abstract. We quantify the snowmelt-albedo feedback at Neumayer Station, East Antarctica, using 24 years (1992–2016) of high-quality meteorological observations to force a surface energy balance model. The modelled 24-year cumulative surface melt at Neumayer amounts to 1060 mm water equivalent (w.e.), with only a small uncertainty (± 3 mm w.e.) from random measurement errors. Results are more sensitive to the chosen value for the surface momentum roughness length and fresh snow density, yielding a range of 800–1140 mm w.e. Melt at Neumayer occurs only in the months November to February, with a summer average of 46 mm w.e. and large interannual variability (σ = 40 mm w.e.). Absorbed shortwave radiation is the dominant driver of temporal melt variability at Neumayer. To assess the importance of the melt-albedo feedback we include and calibrate an albedo parameterisation in the surface energy balance model. We show that, without the snowmelt- albedo feedback, surface melt at Neumayer would be approximately three times weaker, demonstrating how important it is to correctly represent this feedback in model simulations of surface melt.

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“…The advantage of using RCMs is that mass loss associated with water vapor exchanges can be explicitly accounted for, which is critical when determining variations in accumulation and/or surface MB. The Greenland Climate Network (GC-Net) , the Programme for Monitoring of the Greenland Ice Sheet [van As et al, 2013], as well as the automatic weather stations (AWSs) and glaciological measurements along the Kangerlussuaq transect [van de Wal et al, 2012], have been essential in assessing the skill of RCMs. Despite the impressive advances being made in refining these models, which has allowed the uncertainties in estimating MB to be narrowed, there is still a need for detailed atmospheric and glaciological measurements to be undertaken on the GrIS.…”

Section: Introductionmentioning

confidence: 99%

Assessing the role of sublimation in the dry snow zone of the Greenland ice sheet in a warming world

et al. 2014

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Meteorological and glaciological data obtained over an intensive 2 year measurement period (2000)(2001)(2002) are used to run a physically based climatic mass balance model to characterize a seasonal variability in mass and energy exchanges at Summit, Greenland. The model resolves the full surface energy balance and the subsurface temperature profile by inclusion of energy release from penetrating shortwave radiation. A Monte Carlo approach using 1000 different parameter combinations is adopted to assess model uncertainty, with output compared to measured surface and subsurface temperatures, changes in surface height, and eddy correlation data. The heat exchanges associated with the change in phase of water are very small in all seasons, with the average turbulent latent heat flux equal to 0.4 (±0.2) W m À2 . This suggests that the mean annual water vapor gradient is toward the surface, resulting in a mass gain of 4.1 mm WE yr À1 . The mass gain represents only a small fraction of the total accumulation (<2%), in part because of the change in sign of the water vapor flux from winter (deposition) to summer (sublimation), but if assumed to be typical of the entire dry snow zone (40% of the total ice sheet area) is equivalent to approximately 5.5 Gt yr À1 . A simple experiment based on 2012 atmospheric conditions suggests that mass turnover from water vapor exchanges will likely be enhanced in a warming climate, with sublimation increasing more than deposition. Should the sign of the mean turbulent latent heat flux change due to warming, the present mass gain in the dry snow zone could easily become a mass loss of equal proportion, which would further enhance the negative mass balance of the Greenland ice sheet.

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Darkening of the Greenland ice sheet due to the melt albedo feedback observed at PROMICE weather stations

Cited by 22 publications

References 1 publication

Thermal tracing of retained meltwater in the lower accumulation area of the Southwestern Greenland ice sheet

Thermal tracing of retained meltwater in the lower accumulation area of the Southwestern Greenland ice sheet

Quantifying the snowmelt-albedo feedback at Neumayer Station, East Antarctica

Assessing the role of sublimation in the dry snow zone of the Greenland ice sheet in a warming world

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