Large-Scale Surface Mass Balance of Ice Sheets from a Comprehensive Atmospheric Model

Abstract. Ice cores are an important record of the past surface mass balance (SMB) of ice sheets, with SMB mitigating the ice sheets’ sea level impact over the recent decades. For the Antarctic Ice Sheet (AIS), SMB is dominated by large-scale atmospheric circulation, which collects warm moist air from further north and releases it in the form of snow as widespread accumulation or focused atmospheric rivers on the continent. This implies that the snow deposited at the surface of the AIS should record strongly coupled SMB and surface air temperature (SAT) variations. Ice cores use δ18O as a proxy for SAT as they do not record SAT directly. Here, using isotope-enabled global climate models and the RACMO2.3 regional climate model, we calculate positive SMB-SAT and δ18O-SMB correlations over ∼90 % of the AIS. The high spatial resolution of the RACMO2.3 model allows us to highlight a number of areas where SMB and SAT are not correlated, and show that wind-driven processes acting locally, such as Foehn and katabatic effects, can overwhelm the large-scale atmospheric input in SMB and SAT responsible for the positive SMB-SAT correlations. We focus in particular on Dronning Maud Land, East Antarctica, where the ice promontories clearly show these wind-induced effects. However, using the PAGES2k ice core compilations of SMB and δ18O of Thomas et al. (2017) and Stenni et al. (2017), we obtain a weak correlation, on the order of 0.1, between SMB and δ18O over the past ~150 years. We obtain an equivalently weak correlation between ice core SMB and the SAT reconstruction of Nicolas and Bromwich (2014) over the past ~50 years, although the ice core sites are not spatially co-located with the areas displaying a low SMB-SAT correlation in the models. To resolve the discrepancy between the measured and modeled signals, we show that averaging the ice core records in close spatial proximity increases their SMB-SAT correlation. This increase shows that the weak measured correlation likely results from random noise present in the ice core records, but is not large enough to match the correlation calculated in the models. Our results indicate thus a positive correlation between SAT and SMB in models and ice core reconstructions but with a weaker value in observations that may be due to missing processes in models or some systematic biases in ice core data that are not removed by a simple average.

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Design and results of the ice sheet model initialisation experiments initMIP-Greenland: an ISMIP6 intercomparison

The Cryosphere ◽

10.5194/tc-12-1433-2018 ◽

2018 ◽

Vol 12 (4) ◽

pp. 1433-1460 ◽

Cited By ~ 50

Author(s):

Heiko Goelzer ◽

Sophie Nowicki ◽

Tamsin Edwards ◽

Matthew Beckley ◽

Ayako Abe-Ouchi ◽

...

Keyword(s):

Mass Balance ◽

Sea Level ◽

Large Scale ◽

Ice Sheets ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Surface Mass Balance ◽

Model Intercomparison ◽

Surface Mass ◽

Intercomparison Project

Abstract. Earlier large-scale Greenland ice sheet sea-level projections (e.g. those run during the ice2sea and SeaRISE initiatives) have shown that ice sheet initial conditions have a large effect on the projections and give rise to important uncertainties. The goal of this initMIP-Greenland intercomparison exercise is to compare, evaluate, and improve the initialisation techniques used in the ice sheet modelling community and to estimate the associated uncertainties in modelled mass changes. initMIP-Greenland is the first in a series of ice sheet model intercomparison activities within ISMIP6 (the Ice Sheet Model Intercomparison Project for CMIP6), which is the primary activity within the Coupled Model Intercomparison Project Phase 6 (CMIP6) focusing on the ice sheets. Two experiments for the large-scale Greenland ice sheet have been designed to allow intercomparison between participating models of (1) the initial present-day state of the ice sheet and (2) the response in two idealised forward experiments. The forward experiments serve to evaluate the initialisation in terms of model drift (forward run without additional forcing) and in response to a large perturbation (prescribed surface mass balance anomaly); they should not be interpreted as sea-level projections. We present and discuss results that highlight the diversity of data sets, boundary conditions, and initialisation techniques used in the community to generate initial states of the Greenland ice sheet. We find good agreement across the ensemble for the dynamic response to surface mass balance changes in areas where the simulated ice sheets overlap but differences arising from the initial size of the ice sheet. The model drift in the control experiment is reduced for models that participated in earlier intercomparison exercises.

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Reconciling the surface temperature–surface mass balance relationship in models and ice cores in Antarctica over the last 2 centuries

The Cryosphere ◽

10.5194/tc-14-4083-2020 ◽

2020 ◽

Vol 14 (11) ◽

pp. 4083-4102

Author(s):

Marie G. P. Cavitte ◽

Quentin Dalaiden ◽

Hugues Goosse ◽

Jan T. M. Lenaerts ◽

Elizabeth R. Thomas

Keyword(s):

Mass Balance ◽

Large Scale ◽

Random Noise ◽

Ice Core ◽

Ice Sheets ◽

Ice Cores ◽

Surface Mass Balance ◽

Surface Mass ◽

The Past ◽

Ice Core Records

Abstract. Ice cores are an important record of the past surface mass balance (SMB) of ice sheets, with SMB mitigating the ice sheets' sea level impact over the recent decades. For the Antarctic Ice Sheet (AIS), SMB is dominated by large-scale atmospheric circulation, which collects warm moist air from further north and releases it in the form of snow as widespread accumulation or focused atmospheric rivers on the continent. This suggests that the snow deposited at the surface of the AIS should record strongly coupled SMB and surface air temperature (SAT) variations. Ice cores use δ18O as a proxy for SAT as they do not record SAT directly. Here, using isotope-enabled global climate models and the RACMO2.3 regional climate model, we calculate positive SMB–SAT and SMB–δ18O annual correlations over ∼90 % of the AIS. The high spatial resolution of the RACMO2.3 model allows us to highlight a number of areas where SMB and SAT are not correlated, and we show that wind-driven processes acting locally, such as foehn and katabatic effects, can overwhelm the large-scale atmospheric contribution in SMB and SAT responsible for the positive SMB–SAT annual correlations. We focus in particular on Dronning Maud Land, East Antarctica, where the ice promontories clearly show these wind-induced effects. However, using the PAGES2k ice core compilations of SMB and δ18O of Thomas et al. (2017) and Stenni et al. (2017), we obtain a weak annual correlation, on the order of 0.1, between SMB and δ18O over the past ∼150 years. We obtain an equivalently weak annual correlation between ice core SMB and the SAT reconstruction of Nicolas and Bromwich (2014) over the past ∼50 years, although the ice core sites are not spatially co-located with the areas displaying a low SMB–SAT annual correlation in the models. To resolve the discrepancy between the measured and modeled signals, we show that averaging the ice core records in close spatial proximity increases their SMB–SAT annual correlation. This increase shows that the weak measured annual correlation partly results from random noise present in the ice core records, but the change is not large enough to match the annual correlation calculated in the models. Our results thus indicate a positive correlation between SAT and SMB in models and ice core reconstructions but with a weaker value in observations that may be due to missing processes in models or some systematic biases in ice core data that are not removed by a simple average.

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Impact of the choice of surface mass balance models and their calibration on large-scale glacier change projections

10.5194/egusphere-egu21-1391 ◽

2021 ◽

Author(s):

Lilian Schuster ◽

David Rounce ◽

Fabien Maussion

Keyword(s):

Mass Balance ◽

Large Scale ◽

Model Complexity ◽

Model Parameters ◽

Glacier Change ◽

Surface Mass Balance ◽

Ice Dynamics ◽

Surface Mass ◽

Mass Balance Models ◽

Intercomparison Study

<p>A recent large model intercomparison study (GlacierMIP) showed that differences between the glacier models is a dominant source of uncertainty for future glacier change projections, in particular in the first half of the century.&#160; Each glacier model has their own unique set of process representations and climate forcing methodology, which makes it impossible to determine the model components that contribute most to the projection uncertainty. This study aims to improve our understanding of the sources of large scale glacier model uncertainty using the Open Global Glacier Model (OGGM), focussing on the surface mass balance (SMB) in a first step. We calibrate and run a set of interchangeable SMB model parameterizations (e.g. monthly vs. daily, constant vs. variable lapse rates, albedo, snowpack evolution and refreezing) under controlled boundary conditions. Based on ensemble approaches, we explore the influence of (i) the parameter calibration strategy and (ii) SMB model complexity on regional to global glacier change. These uncertainties are then put in relation to a qualitative selection of other model design choices, such as the forcing climate dataset and ice dynamics model parameters.&#160;</p>

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

Annals of Glaciology ◽

10.3189/172756405781813302 ◽

2005 ◽

Vol 41 ◽

pp. 97-104 ◽

Cited By ~ 72

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.

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Temporally stable surface mass balance asymmetry across an ice rise derived from radar internal reflection horizons through inverse modeling

Journal of Glaciology ◽

10.1017/jog.2016.41 ◽

2016 ◽

Vol 62 (233) ◽

pp. 525-534 ◽

Cited By ~ 5

Author(s):

DENIS CALLENS ◽

REINHARD DREWS ◽

EMMANUEL WITRANT ◽

MORGANE PHILIPPE ◽

FRANK PATTYN

Keyword(s):

Mass Balance ◽

Large Scale ◽

Optimization Technique ◽

Internal Reflection ◽

Asymmetric Distribution ◽

Surface Mass Balance ◽

Ice Flow ◽

Atmospheric Flow ◽

Surface Mass ◽

Ice Shelves

ABSTRACTIce rises are locally grounded parts of Antarctic ice shelves that play an important role in regulating ice flow from the continent towards the ocean. Because they protrude out of the otherwise horizontal ice shelves, ice rises induce an orographic uplift of the atmospheric flow, resulting in an asymmetric distribution of the surface mass balance (SMB). Here, we combine younger and older internal reflection horizons (IRHs) from radar to quantify this distribution in time and space across Derwael Ice Rise (DIR), Dronning Maud Land, Antarctica. We employ two methods depending on the age of the IRHs, i.e. the shallow layer approximation for the younger IRHs near the surface and an optimization technique based on an ice flow model for the older IRHs. We identify an SMB ratio of 2.5 between the flanks and the ice divide with the SMB ranging between 300 and 750 kg m−2 a−1. The SMB maximum is located on the upwind side, ~4 km offset to today's topographic divide. The large-scale asymmetry is consistently observed in time until 1966. The SMB from older IRHs is less-well constrained, but the asymmetry has likely persisted for >ka, indicating that DIR has been a stable features over long time spans.

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Impact of solar forcing on the surface mass balance of northern ice sheets for glacial conditions

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2012.04.043 ◽

2012 ◽

Vol 335-336 ◽

pp. 18-24 ◽

Cited By ~ 3

Author(s):

Marie-Noëlle Woillez ◽

Gerhard Krinner ◽

Masa Kageyama ◽

Gilles Delaygue

Keyword(s):

Mass Balance ◽

Ice Sheets ◽

Surface Mass Balance ◽

Solar Forcing ◽

Surface Mass

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Review: “Modelling the climate and surface mass balance of polar ice sheets using RACMO2, Part 1: Greenland (1958-2016)” by Noël et al.

10.5194/tc-2017-201-rc2 ◽

2017 ◽

Author(s):

Anonymous

Keyword(s):

Mass Balance ◽

Ice Sheets ◽

Surface Mass Balance ◽

Polar Ice ◽

Surface Mass ◽

Polar Ice Sheets

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Downscaled surface mass balance in Antarctica: impacts of subsurface processes and large-scale atmospheric circulation

10.5194/tc-2021-69 ◽

2021 ◽

Author(s):

Nicolaj Hansen ◽

Peter L. Langen ◽

Fredrik Boberg ◽

Rene Forsberg ◽

Sebastian B. Simonsen ◽

...

Keyword(s):

Mass Balance ◽

Total Mass ◽

Large Scale ◽

Climate Model ◽

Regional Climate ◽

Surface Mass Balance ◽

Surface Mass ◽

Lagrangian Framework ◽

Basin Scale ◽

The Antarctic

Abstract. Antarctic surface mass balance (SMB) is largely determined by precipitation over the continent and subject to regional climate variability related to the Southern Annular Mode (SAM) and other climatic drivers at the large scale. Locally however, firn and snow pack processes are important in determining SMB and the total mass balance of Antarctica and global sea level. Here, we examine factors that influence Antarctic SMB and attempt to reconcile the outcome with estimates for total mass balance determined from the GRACE satellites. This is done by having the regional climate model HIRHAM5 forcing two versions of an offline subsurface model, to estimate Antarctic ice sheet (AIS) SMB from 1980 to 2017. The Lagrangian subsurface model estimates AIS SMB of 2473.5 ± 114.4 Gt per year, while the Eulerian subsurface model variant results in slightly higher modelled SMB of 2564.8 ± 113.7 Gt per year. The majority of this difference in modelled SMB is due to melt and refreezing over ice shelves and demonstrates the importance of firn modelling in areas with substantial melt. Both the Eulerian and the Lagrangian SMB estimates are within uncertainty ranges of each other and within the range of other SMB studies. However, the Lagrangian version has better statistics when modelling the densities. There is a mean bias in modelled density of −24.0 ± 18.4 kg m−3 and −8.2 ± 15.3 kg m−3 for layers less than 550 kg m−3 for the Eulerian and Lagrangian framework, respectively. For layers with a density above 550 kg m−3 the bias is −31.7 ± 23.4 kg m−3 and −35.0 ± 23.7 kg m−3 for the Eulerian and Lagrangian framework, respectively. The mean firn 10 m temperature bias is 0.42–0.52 °C. Further, analysis of the relationship between SMB in individual drainage basins and the SAM, is carried out using a bootstrapping approach. This shows a robust relationship between SAM and SMB in half of the basins (13 out of 27). In general, when SAM is positive there is a lower SMB over the Plateau and a higher SMB on the westerly side of the Antarctic Peninsula, and vice versa when the SAM is negative. Finally, we compare the modelled SMB to GRACE data by subtracting the solid ice discharge, and find that there is a good agreement in East Antarctica, but large disagreements over the Antarctic Peninsula.There is a large difference between published estimates of discharge that make it challenging to use mass reconciliation in evaluating SMB models on the basin scale.

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