Greenland ice sheet surface mass balance:  evaluating simulations and making projections with regional climate models

Rae, Jamie; Ađalgeirsdóttir, Guðfinna; Edwards, Tamsin; Fettweis, Xavier; Gregory, Jonathan M.; Hewitt, Helene T.; Lowe, Jason; Lucas‐Picher, Philippe; Mottram, Ruth; Payne, Antony J.; Ridley, Jeff; Shannon, Sarah; Berg, Willem Jan van de; Wal, R. S. W. van de; Broeke, M. R. van den

doi:10.5194/tc-6-1275-2012

Cited by 129 publications

(181 citation statements)

References 45 publications

(66 reference statements)

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“…This choice was based on the ability of this model to simulate the Greenland climate compared with observations (e.g. Fettweis and others, 2011;Franco and others, 2012;Rae and others, 2012). However, other climates could be used as reference climatology, such as reanalysis or other regional climate models outputs, for example RACMO (Ettema and others, 2009).…”

Section: Reference Climatologymentioning

confidence: 99%

Ice flux evolution in fast flowing areas of the Greenland ice sheet over the 20th and 21st centuries

et al. 2017

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ABSTRACT. This study investigates the evolution of Greenland ice sheet flux focusing on five of the main fast flowing regions (Petermann glacier, North East Greenland Ice Stream, Kangerdlugssuaq glacier, Helheim glacier and Jakobshavn glacier) in response to 20th and 21st century climate change. A hybrid (shallow ice and shallow shelf) ice-sheet model (ISM) is forced with the combined outputs of a set of seven CMIP5 models and the regional climate model MAR. The ISM simulates the present-day ice velocity pattern, topography and surface mass balance (SMB) in good agreement with observations. Except for the Kangerdlugssuaq glacier, over the 21st century all the fast-flowing areas have exhibited a decrease in ice flux as a result of a negative SMB rather than dynamical changes. Only the fronts of Kangerdlugssuaq and Helheim glaciers have shown an interannual variability driven by dynamical rather than climate changes. Finally, the results predict a substantial inland ice margin retreat by the end of the 21st century, especially along the northern coasts.

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Section: Reference Climatologymentioning

confidence: 99%

Ice flux evolution in fast flowing areas of the Greenland ice sheet over the 20th and 21st centuries

et al. 2017

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“…In both cases, we use simulations supplied by the RCM Modèle Atmosphérique Régional (MAR) (16). Each simulation was driven by atmospheric boundary conditions applied to the periphery of the model domain: For the development of the parameterization, the MAR was driven by the interim reanalysis of the European Centre for Medium-Range Weather Forecasts (ERA-Interim) data (20) (17) and Rae et al (18). A few additional experiments were also performed using the same experimental design but with ECHAM5 run for the E1 scenario (strong mitigation) and the Hadley Centre climate model (HadCM3) run for A1B.…”

Section: Climate Forcingmentioning

confidence: 99%

“…The first stage is an assessment of future changes in meltwater runoff (i.e., the flux of meltwater generated by surface ablation that does not refreeze locally within the snowpack) from the ice sheet. For this we use future projections from a Regional Climate Model (RCM) run over the GrIS at a resolution of 25 km (16)(17)(18). The second stage is to develop an assessment of the effect of this runoff on the sliding experienced by the ice sheet.…”

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confidence: 99%

Enhanced basal lubrication and the contribution of the Greenland ice sheet to future sea-level rise

Shannon

Payne

Bartholomew

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

101

132

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We assess the effect of enhanced basal sliding on the flow and mass budget of the Greenland ice sheet, using a newly developed parameterization of the relation between meltwater runoff and ice flow. A wide range of observations suggest that water generated by melt at the surface of the ice sheet reaches its bed by both fracture and drainage through moulins. Once at the bed, this water is likely to affect lubrication, although current observations are insufficient to determine whether changes in subglacial hydraulics will limit the potential for the speedup of flow. An uncertainty analysis based on our best-fit parameterization admits both possibilities: continuously increasing or bounded lubrication. We apply the parameterization to four higher-order ice-sheet models in a series of experiments forced by changes in both lubrication and surface mass budget and determine the additional mass loss brought about by lubrication in comparison with experiments forced only by changes in surface mass balance. We use forcing from a regional climate model, itself forced by output from the European Centre Hamburg Model (ECHAM5) global climate model run under scenario A1B. Although changes in lubrication generate widespread effects on the flow and form of the ice sheet, they do not affect substantial net mass loss; increase in the ice sheet's contribution to sea-level rise from basal lubrication is projected by all models to be no more than 5% of the contribution from surface mass budget forcing alone.S tudies of alpine glaciers have long demonstrated that seasonally produced surface meltwater drains to the base of these glaciers and causes enhanced basal sliding (i.e., the relative motion of the ice mass base to some underlying immobile substrate) (1). The observation of summer increases in ice velocity near the equilibrium line of the Greenland ice sheet (GrIS) (2) has prompted concerns that warmer climates may lead to accelerated flow and consequent thinning of the ice sheet as both the intensity of surface melt and the area affected by it increase (3).Since the initial Zwally et al. (2) observation, new evidence for a strong link between surface melting and ice-sheet flow has been collected in Greenland. Field observations of coincident uplift and ice acceleration (4) suggest that the drainage of supraglacial lakes to the base of the ice sheet delivers quantities of water to the bed by water-driven fracture propagation. In addition, radarecho surveys show that some moulins provide long-lived, direct hydraulic connections to the bed (5). The largest accelerations also take place downstream of large moulins (6). Satellite and field observations also show pervasive summertime acceleration of the ablation zone of the ice sheet (6-10), although the transmission of fluctuations in velocity by longitudinal stresses complicates the analysis of point observations in relating meltwater input to accelerated flow (11).Ground-based measurements of the flow of the western GrIS over 17 y, on the other hand, indicated that there was a sli...

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“…The release of high-quality and consistent historical weather reanalysis data has made possible the modelling of the processes controlling SMB over the whole ice sheet. Temporal differences between these SMB estimations have been identified (Dahl-Jensen et al, 2009;Rae et al, 2012) yet remain to be explained. Here we consider four such reconstructions of GrIS SMB carried out using a common forcing: re-analysis data from ECMWF.…”

Section: Introductionmentioning

confidence: 99%

Surface mass balance model intercomparison for the Greenland ice sheet

et al. 2013

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Abstract. A number of high resolution reconstructions of the surface mass balance (SMB) of the Greenland ice sheet (GrIS) have been produced using global re-analyses data extending back to 1958. These reconstructions have been used in a variety of applications but little is known about their consistency with each other and the impact of the downscaling method on the result. Here, we compare four reconstructions for the period 1960-2008 to assess the consistency in regional, seasonal and integrated SMB components. Total SMB estimates for the GrIS are in agreement within 34 % of the four model average when a common ice sheet mask is used. When models' native land/ice/sea masks are used this spread increases to 57 %. Variation in the spread of components of SMB from their mean: runoff 42 % (29 % native masks), precipitation 20 % (24 % native masks), melt 38 % (74 % native masks), refreeze 83 % (142 % native masks) show, with the exception of refreeze, a similar level of agreement once a common mask is used. Previously noted differences in the models' estimates are partially explained by ice sheet mask differences. Regionally there is less agreement, suggesting spatially compensating errors improve the integrated estimates.Modelled SMB estimates are compared with in situ observations from the accumulation and ablation areas. Agreement is higher in the accumulation area than the ablation area suggesting relatively high uncertainty in the estimation of ablation processes. Since the mid-1990s each model estimates a decreasing annual SMB. A similar period of decreasing SMB is also estimated for the period 1960-1972. The earlier decrease is due to reduced precipitation with runoff remaining unchanged, however, the recent decrease is associated with increased precipitation, now more than compensated for by increased melt driven runoff. Additionally, in three of the four models the equilibrium line altitude has risen since the mid-1990s, reducing the accumulation area at a rate of approximately 60 000 km 2 per decade due to increased melting. Improving process representation requires further study but the use of a single accurate ice sheet mask is a logical way to reduce uncertainty among models.

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Greenland ice sheet surface mass balance: evaluating simulations and making projections with regional climate models

Cited by 129 publications

References 45 publications

Ice flux evolution in fast flowing areas of the Greenland ice sheet over the 20th and 21st centuries

Ice flux evolution in fast flowing areas of the Greenland ice sheet over the 20th and 21st centuries

Enhanced basal lubrication and the contribution of the Greenland ice sheet to future sea-level rise

Surface mass balance model intercomparison for the Greenland ice sheet

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