scholarly journals Exploration of parametric uncertainty in a surface mass balance model applied to the Greenland ice sheet

2012 ◽  
Vol 117 (F1) ◽  
pp. n/a-n/a ◽  
Author(s):  
P. W. Fitzgerald ◽  
J. L. Bamber ◽  
J. K. Ridley ◽  
J. C. Rougier
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Parametric Uncertainty ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Mass Balance Model ◽  
Surface Mass

scholarly journals A surface mass balance model for the Greenland Ice Sheet

2005 ◽  
Vol 110 (F4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Marion Bougamont ◽  
Jonathan L. Bamber ◽  
Wouter Greuell
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Mass Balance Model ◽  
Surface Mass

scholarly journals Surface mass balance model intercomparison for the Greenland ice sheet

2012 ◽  
Vol 6 (5) ◽  
pp. 3999-4036 ◽  
Author(s):  
C. L. Vernon ◽  
J. L. Bamber ◽  
J. E. Box ◽  
M. R. van den Broeke ◽  
X. Fettweis ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
Process Representation ◽  
Model Average

Abstract. Four simulations of the surface mass balance (SMB) of the Greenland ice sheet (GrIS) are compared over the period 1960–2008. 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 km2 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.

scholarly journals Analysis of the Surface Mass Balance for Deglacial Climate Simulations

2020 ◽  
Author(s):  
Marie-Luise Kapsch ◽  
Uwe Mikolajewicz ◽  
Florian Andreas Ziemen ◽  
Christian B. Rodehacke ◽  
Clemens Schannwell
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Meridional Overturning Circulation ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Equilibrium Line Altitude ◽  
Data Set ◽  
Surface Mass ◽  
Climate Conditions

Abstract. Most studies analyzing changes in the surface mass balance (SMB) of the Greenland ice sheet are limited to the last century, due to the availability of observations and the computational limitations of regional climate modeling. Using transient simulations with a comprehensive Earth System Model (ESM) we extend previous research and study changes in the SMB and equilibrium line altitude (ELA) for deglacial climate conditions. An energy balance model (EBM) is used to downscale atmospheric processes. It determines the SMB on higher spatial resolution and allows to resolve SMB variations due to topographic gradients not resolved by the ESM. An evaluation for historical climate conditions (1980–2010) shows that derived SMBs compare well with SMBs from regional modeling. Throughout the deglaciation changes in insolation dominate the Greenland SMB: 1) The increase in insolation and associated warming early in the deglaciation result in an ELA and SMB increase. The SMB increase is caused by compensating effects of melt and accumulation, as a warmer atmosphere precipitates more. After 13 ka before present (BP) melt begins to dominate and the SMB decreases. 2) The decline in insolation after 9 ka BP leads to an increasing SMB and decreasing ELA. Superimposed on these long-term changes are episodes of significant SMB/ELA decreases, related to slowdowns of the Atlantic Meridional Overturning Circulation (AMOC) that lead to cooling over most of the Northern Hemisphere. To study associated changes in the ice sheet geometry, the SMB data set is made available to the ice sheet modeling community.

scholarly journals An efficient regional energy-moisture balance model for simulation of the Greenland Ice Sheet response to climate change

2010 ◽  
Vol 4 (2) ◽  
pp. 129-144 ◽  
Author(s):  
A. Robinson ◽  
R. Calov ◽  
A. Ganopolski
Keyword(s):  
Mass Balance ◽  
Climate Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Regional Energy ◽  
Temperature And Precipitation ◽  
Moisture Balance

Abstract. In order to explore the response of the Greenland ice sheet (GIS) to climate change on long (centennial to multi-millennial) time scales, a regional energy-moisture balance model has been developed. This model simulates seasonal variations of temperature and precipitation over Greenland and explicitly accounts for elevation and albedo feedbacks. From these fields, the annual mean surface temperature and surface mass balance can be determined and used to force an ice sheet model. The melt component of the surface mass balance is computed here using both a positive degree day approach and a more physically-based alternative that includes insolation and albedo explicitly. As a validation of the climate model, we first simulated temperature and precipitation over Greenland for the prescribed, present-day topography. Our simulated climatology compares well to observations and does not differ significantly from that of a simple parameterization used in many previous simulations. Furthermore, the calculated surface mass balance using both melt schemes falls within the range of recent regional climate model results. For a prescribed, ice-free state, the differences in simulated climatology between the regional energy-moisture balance model and the simple parameterization become significant, with our model showing much stronger summer warming. When coupled to a three-dimensional ice sheet model and initialized with present-day conditions, the two melt schemes both allow realistic simulations of the present-day GIS.

scholarly journals Ice-sheet contributions to future sea-level change

2006 ◽  
Vol 364 (1844) ◽  
pp. 1709-1732 ◽  
Author(s):  
J.M Gregory ◽  
P Huybrechts
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
General Circulation Models ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Global Average

Accurate simulation of ice-sheet surface mass balance requires higher spatial resolution than is afforded by typical atmosphere–ocean general circulation models (AOGCMs), owing, in particular, to the need to resolve the narrow and steep margins where the majority of precipitation and ablation occurs. We have developed a method for calculating mass-balance changes by combining ice-sheet average time-series from AOGCM projections for future centuries, both with information from high-resolution climate models run for short periods and with a 20 km ice-sheet mass-balance model. Antarctica contributes negatively to sea level on account of increased accumulation, while Greenland contributes positively because ablation increases more rapidly. The uncertainty in the results is about 20% for Antarctica and 35% for Greenland. Changes in ice-sheet topography and dynamics are not included, but we discuss their possible effects. For an annual- and area-average warming exceeding in Greenland and in the global average, the net surface mass balance of the Greenland ice sheet becomes negative, in which case it is likely that the ice sheet would eventually be eliminated, raising global-average sea level by 7 m.

Modelling the surface mass balance of the Greenland Ice Sheet from 6000 BP to the year 2200

2020 ◽  
Author(s):  
Uta Krebs-Kanzow ◽  
Shan Xu ◽  
Hu Yang ◽  
Paul Gierz ◽  
Gerrit Lohmann
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Atmospheric Composition ◽  
Balance Model ◽  
Wave Radiation ◽  
System Modelling ◽  
Surface Mass Balance ◽  
Surface Mass

<p>The surface mass balance scheme dEBM (diurnal Energy Balance Model) provides a novel interface between atmosphere and land ice for Earth System modelling, which is based on the energy balance of glaciated surfaces. In contrast to empirical schemes, dEBM accounts for changes in the Earth’s orbit and atmospheric composition. The scheme only requires monthly atmospheric forcing (precipitation, temperature, shortwave and longwave radiation and cloud cover) and is computationally inexpensive, which makes it particularly suitable to investigate the response of ice sheets to long term climate change.<br>Here, we analyze the surface mass balance of the Greenland Ice Sheet (GrIS)  based on a climate simulation which covers the last 6000 years and a climate projection which extends to the year 2200. We validate our results with recent surface mass balance estimates from observations and regional modelling. Our model results allow to compare two distinctly different warm periods: the Mid Holocene (approx. 6000 years before present), which is characterized by intensified summer insolation, and the next centuries,  which will be characterized by reduced outgoing long wave radiation. We also investigate whether the temperature - melt relationship, as used in empirical  schemes, remains stable under changing insolation and atmospheric composition.</p><p><em>Krebs-Kanzow, U., Gierz, P., & Lohmann, G. (2018). Brief communication: An ice surface melt scheme including the diurnal cycle of solar radiation. The Cryosphere, 12(12), 3923-3930.</em></p>

scholarly journals Surface mass balance model intercomparison for the Greenland ice sheet

2013 ◽  
Vol 7 (2) ◽  
pp. 599-614 ◽  
Author(s):  
C. L. Vernon ◽  
J. L. Bamber ◽  
J. E. Box ◽  
M. R. van den Broeke ◽  
X. Fettweis ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
Process Representation ◽  
Model Average ◽  
The Impact

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 km2 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.

Contemporary (1960–2012) Evolution of the Climate and Surface Mass Balance of the Greenland Ice Sheet

2013 ◽  
Vol 35 (5) ◽  
pp. 1155-1174 ◽  
Author(s):  
J. H. van Angelen ◽  
M. R. van den Broeke ◽  
B. Wouters ◽  
J. T. M. Lenaerts
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Surface Mass

scholarly journals Simulation of the future sea level contribution of Greenland with a new glacial system model

2018 ◽  
Vol 12 (10) ◽  
pp. 3097-3121 ◽  
Author(s):  
Reinhard Calov ◽  
Sebastian Beyer ◽  
Ralf Greve ◽  
Johanna Beckmann ◽  
Matteo Willeit ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Surface Temperature ◽  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
System Model ◽  
Surface Mass Balance ◽  
Surface Mass

Abstract. We introduce the coupled model of the Greenland glacial system IGLOO 1.0, including the polythermal ice sheet model SICOPOLIS (version 3.3) with hybrid dynamics, the model of basal hydrology HYDRO and a parameterization of submarine melt for marine-terminated outlet glaciers. The aim of this glacial system model is to gain a better understanding of the processes important for the future contribution of the Greenland ice sheet to sea level rise under future climate change scenarios. The ice sheet is initialized via a relaxation towards observed surface elevation, imposing the palaeo-surface temperature over the last glacial cycle. As a present-day reference, we use the 1961–1990 standard climatology derived from simulations of the regional atmosphere model MAR with ERA reanalysis boundary conditions. For the palaeo-part of the spin-up, we add the temperature anomaly derived from the GRIP ice core to the years 1961–1990 average surface temperature field. For our projections, we apply surface temperature and surface mass balance anomalies derived from RCP 4.5 and RCP 8.5 scenarios created by MAR with boundary conditions from simulations with three CMIP5 models. The hybrid ice sheet model is fully coupled with the model of basal hydrology. With this model and the MAR scenarios, we perform simulations to estimate the contribution of the Greenland ice sheet to future sea level rise until the end of the 21st and 23rd centuries. Further on, the impact of elevation–surface mass balance feedback, introduced via the MAR data, on future sea level rise is inspected. In our projections, we found the Greenland ice sheet to contribute between 1.9 and 13.0 cm to global sea level rise until the year 2100 and between 3.5 and 76.4 cm until the year 2300, including our simulated additional sea level rise due to elevation–surface mass balance feedback. Translated into additional sea level rise, the strength of this feedback in the year 2100 varies from 0.4 to 1.7 cm, and in the year 2300 it ranges from 1.7 to 21.8 cm. Additionally, taking the Helheim and Store glaciers as examples, we investigate the role of ocean warming and surface runoff change for the melting of outlet glaciers. It shows that ocean temperature and subglacial discharge are about equally important for the melting of the examined outlet glaciers.

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