scholarly journals The Antarctic surface mass balance in a stretched grid general circulation model

1997 ◽  
Vol 25 ◽  
pp. 73-78 ◽  
Author(s):  
Gerhard Krinner ◽  
Christophe Genthon
Keyword(s):  
Mass Balance ◽  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
Horizontal Resolution ◽  
Spatial And Temporal Variability ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Simulated Surface ◽  
The Antarctic

The Laboratoire de Météorologie Dynamique (LMD) variable-grid atmospheric general circulation model (AGCM) was used in this study for a five-year high-resolution simulation of the Antarctic climate. The horizontal resolution is about 100 km over a large part of the ice sheet. This study focuses on the simulated surface mass balance (precipitation-evaporation sublimation-melt) and on the spatial and temporal variability of snowfall in Antarctica. The simulated annual mean surface mass balance for the whole continent is close to the observed value, and the model simulates well the spatial distribution of the surface mass balance. The annual cycle of snowfall exhibits a clear minimum in summer over the high interior plateau as well as for Antarctica as a whole, in agreement with the observations. In the interior of the continent, the model produces a permanent light background snowfall that accounts for about 5% of the total annual precipitation. The bulk of the snowfall is produced irregularly during periods that generally last only two or three days that are caused by cyclones off the coast.

scholarly journals The Antarctic surface mass balance in a stretched grid general circulation model

1997 ◽  
Vol 25 ◽  
pp. 73-78 ◽  
Author(s):  
Gerhard Krinner ◽  
Christophe Genthon
Keyword(s):  
Mass Balance ◽  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
Horizontal Resolution ◽  
Spatial And Temporal Variability ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Simulated Surface ◽  
The Antarctic

The Laboratoire de Météorologie Dynamique (LMD) variable-grid atmospheric general circulation model (AGCM) was used in this study for a five-year high-resolution simulation of the Antarctic climate. The horizontal resolution is about 100 km over a large part of the ice sheet. This study focuses on the simulated surface mass balance (precipitation-evaporation sublimation-melt) and on the spatial and temporal variability of snowfall in Antarctica. The simulated annual mean surface mass balance for the whole continent is close to the observed value, and the model simulates well the spatial distribution of the surface mass balance. The annual cycle of snowfall exhibits a clear minimum in summer over the high interior plateau as well as for Antarctica as a whole, in agreement with the observations. In the interior of the continent, the model produces a permanent light background snowfall that accounts for about 5% of the total annual precipitation. The bulk of the snowfall is produced irregularly during periods that generally last only two or three days that are caused by cyclones off the coast.

scholarly journals Simulating the Early Holocene demise of the Laurentide Ice Sheet with BISICLES (public trunk revision 3298)

2020 ◽  
Vol 13 (9) ◽  
pp. 4555-4577
Author(s):  
Ilkka S. O. Matero ◽  
Lauren J. Gregoire ◽  
Ruza F. Ivanovic
Keyword(s):  
Mass Balance ◽  
General Circulation ◽  
Ice Sheet ◽  
Circulation Model ◽  
Early Holocene ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
The North

Abstract. Simulating the demise of the Laurentide Ice Sheet covering Hudson Bay in the Early Holocene (10–7 ka) is important for understanding the role of accelerated changes in ice sheet topography and melt in the 8.2 ka event, a century long cooling of the Northern Hemisphere by several degrees. Freshwater released from the ice sheet through a surface mass balance instability (known as the saddle collapse) has been suggested as a major forcing for the 8.2 ka event, but the temporal evolution of this pulse has not been constrained. Dynamical ice loss and marine interactions could have significantly accelerated the ice sheet demise, but simulating such processes requires computationally expensive models that are difficult to configure and are often impractical for simulating past ice sheets. Here, we developed an ice sheet model setup for studying the Laurentide Ice Sheet's Hudson Bay saddle collapse and the associated meltwater pulse in unprecedented detail using the BISICLES ice sheet model, an efficient marine ice sheet model of the latest generation which is capable of refinement to kilometre-scale resolutions and higher-order ice flow physics. The setup draws on previous efforts to model the deglaciation of the North American Ice Sheet for initialising the ice sheet temperature, recent ice sheet reconstructions for developing the topography of the region and ice sheet, and output from a general circulation model for a representation of the climatic forcing. The modelled deglaciation is in agreement with the reconstructed extent of the ice sheet, and the associated meltwater pulse has realistic timing. Furthermore, the peak magnitude of the modelled meltwater equivalent (0.07–0.13 Sv) is compatible with geological estimates of freshwater discharge through the Hudson Strait. The results demonstrate that while improved representations of the glacial dynamics and marine interactions are key for correctly simulating the pattern of Early Holocene ice sheet retreat, surface mass balance introduces by far the most uncertainty. The new model configuration presented here provides future opportunities to quantify the range of plausible amplitudes and durations of a Hudson Bay ice saddle collapse meltwater pulse and its role in forcing the 8.2 ka event.

scholarly journals The modelled surface mass balance of the Antarctic Peninsula at 5.5 km horizontal resolution

2016 ◽  
Vol 10 (1) ◽  
pp. 271-285 ◽  
Author(s):  
J. M. van Wessem ◽  
S. R. M. Ligtenberg ◽  
C. H. Reijmer ◽  
W. J. van de Berg ◽  
M. R. van den Broeke ◽  
...  
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Climate Model ◽  
Horizontal Resolution ◽  
Surface Mass Balance ◽  
Data Sets ◽  
High Accumulation ◽  
Surface Mass ◽  
Meltwater Runoff ◽  
The Antarctic

Abstract. This study presents a high-resolution (∼  5.5 km) estimate of surface mass balance (SMB) over the period 1979–2014 for the Antarctic Peninsula (AP), generated by the regional atmospheric climate model RACMO2.3 and a firn densification model (FDM). RACMO2.3 is used to force the FDM, which calculates processes in the snowpack, such as meltwater percolation, refreezing and runoff. We evaluate model output with 132 in situ SMB observations and discharge rates from six glacier drainage basins, and find that the model realistically simulates the strong spatial variability in precipitation, but that significant biases remain as a result of the highly complex topography of the AP. It is also clear that the observations significantly underrepresent the high-accumulation regimes, complicating a full model evaluation. The SMB map reveals large accumulation gradients, with precipitation values above 3000 mm we yr−1 in the western AP (WAP) and below 500 mm we yr−1 in the eastern AP (EAP), not resolved by coarser data sets such as ERA-Interim. The average AP ice-sheet-integrated SMB, including ice shelves (an area of 4.1  ×  105 km2), is estimated at 351 Gt yr−1 with an interannual variability of 58 Gt yr−1, which is dominated by precipitation (PR) (365 ± 57 Gt yr−1). The WAP (2.4  ×  105 km2) SMB (276 ± 47 Gt yr−1), where PR is large (276 ± 47 Gt yr−1), dominates over the EAP (1.7  ×  105 km2) SMB (75 ± 11 Gt yr−1) and PR (84 ± 11 Gt yr−1). Total sublimation is 11 ± 2 Gt yr−1 and meltwater runoff into the ocean is 4 ± 4 Gt yr−1. There are no significant trends in any of the modelled AP SMB components, except for snowmelt that shows a significant decrease over the last 36 years (−0.36 Gt yr−2).

scholarly journals Characteristics of the Antarctic surface mass balance, 1958–2002, using a regional atmospheric climate model

2005 ◽  
Vol 41 ◽  
pp. 97-104 ◽  
Author(s):  
W.J. Van De Berg ◽  
M.R. Van Den Broeke ◽  
C.H. Reijmer ◽  
E. Van Meijgaard
Keyword(s):  
Mass Balance ◽  
Large Scale ◽  
Climate Model ◽  
Horizontal Resolution ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Solid Precipitation ◽  
Temporal And Spatial Characteristics ◽  
The Antarctic ◽  
Regional Atmospheric Climate Model

AbstractTemporal and spatial characteristics of the Antarctic specific surface mass balance (SSMB) are presented, including its components solid precipitation, sublimation/deposition and melt. For this purpose, we use the output of a regional atmospheric climate model (RACMO2/ANT, horizontal resolution of ~55 km) for the period 1958–2002. RACMO2/ANT uses European Centre for Medium-Range Weather Forecasts (ECMWF) 40 year re-analysis (ERA-40) fields as forcing at the lateral boundaries. RACMO2/ANT underestimates SSMB in the high interior of East and West Antarctica and overestimates SSMB on the steep coastal slopes. Otherwise, the modeled spatial pattern of SSMB is in good qualitative agreement with recent compilations of in situ observations. Large-scale patterns, like the precipitation shadow effect of the Antarctic Peninsula, are well reproduced, and mesoscale SSMB patterns, such as the strong precipitation gradients on Law Dome, are well represented in the model. The integrated SSMB over the grounded ice sheet is 153mmw.e. a–1 for the period 1958–2002, which agrees within 5% with the latest measurement compilations. Sublimation and melt remove 7% and <1% respectively of the solid precipitation. We found significant seasonality of solid precipitation, with a maximum in autumn and a minimum in summer. No meaningful trend was identified for the SSMB, because the time series of solid precipitation and SSMB are affected by an inhomogeneity in 1980 within the ERA-40 fields that drive RACMO2/ANT. Sublimation, melt and liquid precipitation increase in time, which is related to a modeled increase in 2m temperature.

scholarly journals Greenland Ice Sheet Surface Mass-Balance Modeling in a 131-Yr Perspective, 1950–2080

2010 ◽  
Vol 11 (1) ◽  
pp. 3-25 ◽  
Author(s):  
Sebastian H. Mernild ◽  
Glen E. Liston ◽  
Christopher A. Hiemstra ◽  
Jens H. Christensen
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Circulation Model ◽  
Change Scenario ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Freshwater Runoff

Abstract Fluctuations in the Greenland ice sheet (GrIS) surface mass balance (SMB) and freshwater influx to the surrounding oceans closely follow climate fluctuations and are of considerable importance to the global eustatic sea level rise. A state-of-the-art snow-evolution modeling system (SnowModel) was used to simulate variations in the GrIS melt extent, surface water balance components, changes in SMB, and freshwater influx to the ocean. The simulations are based on the Intergovernmental Panel on Climate Change scenario A1B modeled by the HIRHAM4 regional climate model (RCM) using boundary conditions from the ECHAM5 atmosphere–ocean general circulation model (AOGCM) from 1950 through 2080. In situ meteorological station [Greenland Climate Network (GC-Net) and World Meteorological Organization (WMO) Danish Meteorological Institute (DMI)] observations from inside and outside the GrIS were used to validate and correct RCM output data before they were used as input for SnowModel. Satellite observations and independent SMB studies were used to validate the SnowModel output and confirm the model’s robustness. The authors simulated an ∼90% increase in end-of-summer surface melt extent (0.483 × 106 km2) from 1950 to 2080 and a melt index (above 2000-m elevation) increase of 138% (1.96 × 106 km2 × days). The greatest difference in melt extent occurred in the southern part of the GrIS, and the greatest changes in the number of melt days were seen in the eastern part of the GrIS (∼50%–70%) and were lowest in the west (∼20%–30%). The rate of SMB loss, largely tied to changes in ablation processes, leads to an enhanced average loss of 331 km3 from 1950 to 2080 and an average SMB level of −99 km3 for the period 2070–80. GrIS surface freshwater runoff yielded a eustatic rise in sea level from 0.8 ± 0.1 (1950–59) to 1.9 ± 0.1 mm (2070–80) sea level equivalent (SLE) yr−1. The accumulated GrIS freshwater runoff contribution from surface melting equaled 160-mm SLE from 1950 through 2080.

scholarly journals Ice-sheets’ surface mass-balance evaluation in the UGAMP GCM: the climate of Antarctica

1996 ◽  
Vol 23 ◽  
pp. 167-173
Author(s):  
I. Marsiat
Keyword(s):  
Mass Balance ◽  
General Circulation ◽  
Ice Sheets ◽  
Circulation Model ◽  
General Circulation Models ◽  
High Latitudes ◽  
Accumulation Pattern ◽  
Surface Mass ◽  
The Antarctic ◽  
Good Agreement

General Circulation Models (GCMs) will be more and more used for coupled climatic simulations involving ice sheets. It is therefore of prime importance to evaluate the performance of these models in simulating the mass balance and climate over ice sheets. The Antarctic climate simulated with the U.K. Universities Global Atmospheric Modelling Programme General Circulation Model (UGAMP GCM, hereafter referred to as the UGCM) is in good agreement with the available observations. In particular, the accumulation pattern appears fairly reasonable. Some imperfections are related to the surface temperature and energy budget but without severe consequences for the atmosphere behaviour. Refining the snow-related parameterizations could improve the results of the model in high latitudes.

scholarly journals Sensitivity of the current Antarctic surface mass balance to sea surface conditions using MAR

2018 ◽  
Vol 12 (12) ◽  
pp. 3827-3839 ◽  
Author(s):  
Christoph Kittel ◽  
Charles Amory ◽  
Cécile Agosta ◽  
Alison Delhasse ◽  
Sébastien Doutreloup ◽  
...  
Keyword(s):  
Mass Balance ◽  
General Circulation ◽  
Sea Surface ◽  
Cmip5 Models ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Surface Conditions ◽  
Continental Scale ◽  
Sensitivity Experiments ◽  
The Antarctic

Abstract. Estimates for the recent period and projections of the Antarctic surface mass balance (SMB) often rely on high-resolution polar-oriented regional climate models (RCMs). However, RCMs require large-scale boundary forcing fields prescribed by reanalyses or general circulation models (GCMs). Since the recent variability of sea surface conditions (SSCs, namely sea ice concentration, SIC, and sea surface temperature, SST) over the Southern Ocean is not reproduced by most GCMs from the 5th phase of the Coupled Model Intercomparison Project (CMIP5), RCMs are then subject to potential biases. We investigate here the direct sensitivity of the Antarctic SMB to SSC perturbations around the Antarctic. With the RCM “Modèle Atmosphérique Régional” (MAR), different sensitivity experiments are performed over 1979–2015 by modifying the ERA-Interim SSCs with (i) homogeneous perturbations and (ii) mean anomalies estimated from all CMIP5 models and two extreme ones, while atmospheric lateral boundary conditions remained unchanged. Results show increased (decreased) precipitation due to perturbations inducing warmer, i.e. higher SST and lower SIC (colder, i.e. lower SST and higher SIC), SSCs than ERA-Interim, significantly affecting the SMB of coastal areas, as precipitation is mainly related to cyclones that do not penetrate far into the continent. At the continental scale, significant SMB anomalies (i.e greater than the interannual variability) are found for the largest combined SST/SIC perturbations. This is notably due to moisture anomalies above the ocean, reaching sufficiently high atmospheric levels to influence accumulation rates further inland. Sensitivity experiments with warmer SSCs based on the CMIP5 biases reveal integrated SMB anomalies (+5 % to +13 %) over the present climate (1979–2015) in the lower range of the SMB increase projected for the end of the 21st century.

scholarly journals The modelled surface mass balance of the Antarctic Peninsula at 5.5 km horizontal resolution

2015 ◽  
Vol 9 (5) ◽  
pp. 5097-5136
Author(s):  
J. M. van Wessem ◽  
S. R. M. Ligtenberg ◽  
C. H. Reijmer ◽  
W. J. van de Berg ◽  
M. R. van den Broeke ◽  
...  
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
Climate Model ◽  
Horizontal Resolution ◽  
Surface Mass Balance ◽  
High Accumulation ◽  
Surface Mass ◽  
Ice Shelves ◽  
Meltwater Runoff ◽  
The Antarctic

Abstract. This study presents a high-resolution (~ 5.5 km) estimate of Surface Mass Balance (SMB) over the period 1979–2014 for the Antarctic Peninsula (AP), generated by the regional atmospheric climate model RACMO2.3 and a Firn Densification Model (FDM). RACMO2.3 is used to force the FDM, which calculates processes in the snowpack, such as meltwater percolation, refreezing and runoff. We evaluate model output with 132 in-situ SMB observations and discharge rates from 6 glacier drainage basins, and find that the model realistically simulates the strong spatial variability in precipitation, but that significant biases remain as a result of the highly complex topography of the AP. It is also clear that the observations significantly underrepresent the high-accumulation regimes. The SMB map reveals large accumulation gradients, with precipitation values above 3000 mm we yr−1 over the western AP (WAP) and below 500 mm we yr−1 on the eastern AP (EAP), not resolved by coarser data-sets such as ERA-Interim. The other SMB components are one order of magnitude smaller, with drifting snow sublimation the largest ablation term removing up to 100 mm we yr−1 of mass. Snowmelt is widespread over the AP, reaching 500 mm we yr−1 towards the northern ice shelves, but the meltwater mostly refreezes. As a result runoff fluxes are low, but still considerable (200 mm we yr−1) over the Larsen (B/C), Wilkins and George VI ice shelves. The average AP ice sheet integrated SMB, including ice shelves (an area of 4.1 × 105 km2), is estimated at 351 Gt yr−1 with an interannual variability of 58 Gt yr−1, which is dominated by precipitation (PR) (365 ± 57 Gt yr−1). The WAP (2.4 × 105 km2) SMB (276 ± 47 Gt yr−1), where PR is large (276 ± 47 Gt yr−1), dominates over the EAP (1.7 × 105 km2) SMB (75 ± 11 Gt yr−1) and PR (84 ± 11 Gt yr−1). Total sublimation is 11 ± 2 Gt yr−1 and meltwater runoff into the ocean is 4 ± 4 Gt yr−1. There are no significant trends in any of the AP SMB components, except for snowmelt that shows a significant decrease over the last 36 years (−0.36 Gt yr−2).

scholarly journals Ice-sheets’ surface mass-balance evaluation in the UGAMP GCM: the climate of Antarctica

1996 ◽  
Vol 23 ◽  
pp. 167-173 ◽  
Author(s):  
I. Marsiat
Keyword(s):  
Mass Balance ◽  
General Circulation ◽  
Ice Sheets ◽  
Circulation Model ◽  
General Circulation Models ◽  
High Latitudes ◽  
Accumulation Pattern ◽  
Surface Mass ◽  
The Antarctic ◽  
Good Agreement

General Circulation Models (GCMs) will be more and more used for coupled climatic simulations involving ice sheets. It is therefore of prime importance to evaluate the performance of these models in simulating the mass balance and climate over ice sheets. The Antarctic climate simulated with the U.K. Universities Global Atmospheric Modelling Programme General Circulation Model (UGAMP GCM, hereafter referred to as the UGCM) is in good agreement with the available observations. In particular, the accumulation pattern appears fairly reasonable. Some imperfections are related to the surface temperature and energy budget but without severe consequences for the atmosphere behaviour. Refining the snow-related parameterizations could improve the results of the model in high latitudes.

scholarly journals High-resolution simulations of the surface mass balance of Greenland at the end of this century

2007 ◽  
Vol 1 (2) ◽  
pp. 351-383 ◽  
Author(s):  
G. Krinner ◽  
N. Julien
Keyword(s):  
Mass Balance ◽  
General Circulation ◽  
Region Of Interest ◽  
Circulation Model ◽  
Meridional Overturning Circulation ◽  
Strong Increase ◽  
Freshwater Flux ◽  
Surface Mass Balance ◽  
Positive Contribution ◽  
Surface Mass

Abstract. We present atmospheric general circulation model simulations of the present (1981–2005) and future (2081–2100) climate according to the SRES A1B greenhouse gas scenario. Focusing on Greenland, we use a stretched grid in the global model, thereby reaching a horizontal grid spacing of 60 km in the region of interest. This allows to capture reasonably the escarpment zone of the ice sheet. For the end of this century, the model suggests a precipitation increase in the central region of Greenland, which is overcompensated for by a strong increase of meltwater production in the lower areas. We calculate the changes of water fluxes into the adjacent seas according the simulated surface mass balances changes. The calculated freshwater flux at the end of the 21st century appears too weak to induce a significant reduction of the meridional overturning circulation in the North Atlantic. The resulting surface mass balance decrease between the last decades of the 20th and 21st centuries is equivalent to a positive contribution of 0.8 mm yr−1 to global eustatic sea-level rise.

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