Numerical modelling of the energy balance and the englacial temperature of the Greenland Ice Sheet. Calculations for the ETH-Camp location (West Greenland, 1155 m a.s.l.)

Greuell, Wouter; Konzelmann, Thomas

doi:10.1016/0921-8181(94)90010-8

Cited by 202 publications

(291 citation statements)

References 24 publications

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“…The latter is controlled by (1) the water availability, (2) the space availability, and (3) the temperature within the snowpack [Bougamont et al, 2005;Greuell and Konzelmann, 1994]. Sensitivity experiments on the mass balance model indicate that the englacial parameterization is most affected by uncertainties in the equation used for conductivity and for energy penetration [Greuell and Konzelmann, 1994]. However, the effects of those on the net SMB remain limited compared to the effect of uncertainties in albedo and precipitation [Greuell and Konzelmann, 1994].…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, the EBSM tunable parameters expected to have the greatest impact on mass balance affect mostly the melt generation (via the surface albedo as well as the timescale for runoff formation), and less so the refreezing processes. The latter is controlled by (1) the water availability, (2) the space availability, and (3) the temperature within the snowpack [Bougamont et al, 2005;Greuell and Konzelmann, 1994]. Sensitivity experiments on the mass balance model indicate that the englacial parameterization is most affected by uncertainties in the equation used for conductivity and for energy penetration [Greuell and Konzelmann, 1994].…”

Section: Resultsmentioning

confidence: 99%

“…However, the PDDM parameters used here have been derived from field observations and are relatively realistic [Braithwaite, 1995;Lefebre et al, 2002]. The EBSM was originally tuned to match in-situ observations of mass balance along the K-Transect [Bougamont et al, 2005] and ETH-Camp [Greuell and Konzelmann, 1994] in southwest Greenland. Moreover, the EBSM tunable parameters expected to have the greatest impact on mass balance affect mostly the melt generation (via the surface albedo as well as the timescale for runoff formation), and less so the refreezing processes.…”

Section: Resultsmentioning

confidence: 99%

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Impact of model physics on estimating the surface mass balance of the Greenland ice sheet

Bougamont

Bamber

Ridley

et al. 2007

Geophysical Research Letters

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[1] Long-term predictions of sea level rise from increased Greenland ice sheet melting have been derived using Positive Degree Day models only. It is, however, unknown precisely what uncertainties are associated with applying this simple surface melt parameterization for future climate. We compare the behavior of a Positive Degree Day and Energy Balance/Snowpack model for estimating the surface mass balance of the Greenland ice sheet under a warming climate. Both models were first tuned to give similar values for present-day mass balance using 10 years of ERA-40 climatology and were then run for 300 years, forced with the output of a GCM in which atmospheric CO 2 increased to 4 times preindustrial levels. Results indicate that the Positive Degree Day model is more sensitive to climate warming than the Energy Balance model, generating annual runoff rates almost twice as large for a fixed ice sheet geometry. Roughly half of this difference was due to differences in the volume of melt generated and half was due to differences in refreezing rates in the snowpack. Our results indicate that the modeled snowpack properties evolve on a multidecadal timescale to changing climate, with a potentially large impact on the mass balance of the ice sheet; an evolution that was absent from the Positive Degree Day model. Citation: Bougamont, M.,

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Impact of model physics on estimating the surface mass balance of the Greenland ice sheet

Bougamont

Bamber

Ridley

et al. 2007

Geophysical Research Letters

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“…Clouds, solar zenith angle and impurities due to soot and dust also have an impact on albedo. In previous model versions of RACMO2, broadband albedo was snow densitydependent (Greuell and Konzelmann, 1994). Although the density of snow is a measure for snow metamorphism, as it usually increases with increasing grain size, a density dependent albedo scheme is unphysical (Wiscombe and Warren, 1980).…”

Section: Albedo Schemementioning

confidence: 99%

Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

et al. 2012

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Abstract. We present a sensitivity study of the surface mass balance (SMB) of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo scheme. The snow albedo scheme uses grain size as a prognostic variable and further depends on cloud cover, solar zenith angle and black carbon concentration. For the control experiment the overestimation of absorbed shortwave radiation (+6 %) at the K-transect (west Greenland) for the period 2004-2009 is considerably reduced compared to the previous density-dependent albedo scheme (+22 %). To simulate realistic snow albedo values, a small concentration of black carbon is needed, which has strongest impact on melt in the accumulation area. A background ice albedo field derived from MODIS imagery improves the agreement between the modeled and observed SMB gradient along the K-transect. The effect of enhanced meltwater retention and refreezing is a decrease of the albedo due to an increase in snow grain size. As a secondary effect of refreezing the snowpack is heated, enhancing melt and further lowering the albedo. Especially in a warmer climate this process is important, since it reduces the refreezing potential of the firn layer that covers the Greenland Ice Sheet.

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“…In turn, these models require validation from in situ observations at the ice sheet surface (Ettema et al, 2010a, b). Owing to the difficult terrain in the GrIS ablation zone with crevasses, slush formation and the presence of meltwater lakes (Box and Ski, 2007), only a few SEB time series are available to date (Ambach, 1977;Greuell and Konzelmann, 1994;Oerlemans and Vugts, 1993;Henneken et al, 1994;Van de Wal and Russell, 1994;Bøggild et al, 1994;Konzelmann and Braithwaite, 1995;Heinemann, 1999). Most experiments lasted only for (part of) a single ablation season, neither capturing the wintertime climate nor the interannual variability.…”

Section: Introductionmentioning

confidence: 99%

The seasonal cycle and interannual variability of surface energy balance and melt in the ablation zone of the west Greenland ice sheet

2011

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Abstract. We present the seasonal cycle and interannual variability of the surface energy balance (SEB) in the ablation zone of the west Greenland ice sheet, using seven years (S9) at distances of 6, 38 and 88 km from the ice sheet margin. The hourly AWS data are fed into a model that calculates all SEB components and melt rate; the model allows for shortwave radiation penetration in ice and time-varying surface momentum roughness. Snow depth is prescribed from albedo and sonic height ranger observations. Modelled and observed surface temperatures for non-melting conditions agree very well, with RMSE's of 0.97-1.26 K. Modelled and observed ice melt rates at the two lowest sites also show very good agreement, both for total cumulative and 10-day cumulated amounts. Melt frequencies and melt rates at the AWS sites are discussed. Although absorbed shortwave radiation is the most important energy source for melt at all three sites, interannual melt variability at the lowest site is driven mainly by variability in the turbulent flux of sensible heat. This is explained by the quasi-constant summer albedo in the lower ablation zone, limiting the influence of the melt-albedo feedback, and the proximity of the snow free tundra, which heats up considerably in summer.Correspondence to: M. R. van den Broeke (m.r.vandenbroeke@uu.nl)

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Numerical modelling of the energy balance and the englacial temperature of the Greenland Ice Sheet. Calculations for the ETH-Camp location (West Greenland, 1155 m a.s.l.)

Cited by 202 publications

References 24 publications

Impact of model physics on estimating the surface mass balance of the Greenland ice sheet

Impact of model physics on estimating the surface mass balance of the Greenland ice sheet

Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

The seasonal cycle and interannual variability of surface energy balance and melt in the ablation zone of the west Greenland ice sheet

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