Calculation of mass discharge of the Greenland ice sheet in the Earth System Model

Abstract. In this study, the resolution dependence of the simulated Greenland Ice Sheet surface mass balance in the variable-resolution Community Earth System Model (VR-CESM) is investigated. Coupled atmosphere-land simulations are performed on three regionally refined grids over Greenland at 1° (~111 km), 0.5°(~55 km), and 0.25° (~28 km), maintaining a quasi-uniform resolution of 1° (~111 km) over the rest of the globe. The SMB in the accumulation zone is significantly improved compared to airborne radar and in-situ observations, with a general wetting at the margins and a drying in the interior GrIS. Total precipitation decreases with resolution, which is in line with best-available regional climate model results. In the ablation zone, VR-CESM starts developing a positive SMB bias in some locations. Potential driving mechanisms are proposed, amongst which are diversions in large scale circulation, changes in cloud cover, and changes in summer snowfall. Overall, our results demonstrate that VR-CESM is a viable new tool in the cryospheric sciences and can be used to dynamically downscale future scenarios and/or be interactively coupled to dynamical ice sheet models.

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Review of Lenaerts et al. “Present-day and future Greenland Ice Sheet precipitation frequency from satellite observations and an Earth System Model”

10.5194/tc-2020-31-rc1 ◽

2020 ◽

Author(s):

Anonymous

Keyword(s):

Ice Sheet ◽

Greenland Ice Sheet ◽

Earth System Model ◽

Satellite Observations ◽

System Model ◽

Earth System ◽

Precipitation Frequency

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Surface Mass Balance of the Greenland Ice Sheet in the Energy Exascale Earth System Model

10.5194/egusphere-egu21-14017 ◽

2021 ◽

Author(s):

Adam Schneider ◽

Stephen Price ◽

Jonathan Wolfe ◽

Charles Zender

Keyword(s):

Sea Level ◽

Climate Model ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Earth System Model ◽

System Model ◽

Surface Mass Balance ◽

Earth System ◽

Surface Mass ◽

Global Sea Level

<p>Since 1993, nearly 10 percent of the observed rise in global mean sea level can be attributed to the coincident increase in surface mass loss from the Greenland Ice Sheet (GrIS) (Meredith et al., 2019; WCRP, 2018). To determine the GrIS surface mass balance (SMB), defined as the ice sheet&#8217;s annual net (surface) mass increase due to snow accumulation minus ablation, a climate model can be coupled to a snowpack model, which enables simulating relevant hydrologic processes including precipitation, phase changes, and runoff. Recent developments within the Energy Exascale Earth System Model (E3SM) include an active ice sheet component. To explore GrIS snowpack conditions relevant to present-day climate, we conduct simulations demonstrating the evolution of SMB and accumulation of snowpack depth, first in E3SM&#8217;s land component (ELM). After forcing ELM&#8217;s surface condition using 20th century atmospheric reanalysis, we couple ELM to E3SM&#8217;s atmosphere component (EAM) and simulate both atmospheric and snowpack conditions over a fixed GrIS geometry. Finally, we activate the MPAS-Albany Land Ice model (MALI), which enables prognostic SMB calculations including elevation-change feedbacks. We find broad agreement in the spatial patterns of GrIS SMB compared to regional climate model (RACMO) and Community Earth System Model (CESM) simulations. We provide insights regarding the use of a statistical downscaling method, which involves using multiple elevation classes with time-varying areal coverages within ELM grid-cells. Within this dynamic system, we can begin investigating elevation feedbacks, where the atmospheric temperature lapse rate allows the SMB to accelerate both positively and negatively in a rapidly changing climate.</p><p>References</p><ul><li>Meredith, M., M. Sommerkorn, S. Cassotta, C. Derksen, A. Ekaykin, A. Hollowed, G. Kofinas, A. Mackintosh, J. Melbourne-Thomas, M.M.C. Muelbert, G. Ottersen, H. Pritchard, and E.A.G. Schuur, 2019: Polar Regions. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Po&#776;rtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegri&#769;a, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. In press.</li> <li>WCRP Global Sea Level Budget Group: Global sea-level budget 1993&#8211;present, Earth Syst. Sci. Data, 10, 1551&#8211;1590, https://doi.org/10.5194/essd-10-1551-2018, 2018.</li> </ul>

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Brief communication: CESM2 climate forcing (1950–2014) yields realistic Greenland ice sheet surface mass balance

The Cryosphere ◽

10.5194/tc-14-1425-2020 ◽

2020 ◽

Vol 14 (4) ◽

pp. 1425-1435 ◽

Cited By ~ 2

Author(s):

Brice Noël ◽

Leonardus van Kampenhout ◽

Willem Jan van de Berg ◽

Jan T. M. Lenaerts ◽

Bert Wouters ◽

...

Keyword(s):

Mass Loss ◽

Mass Balance ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Earth System Model ◽

Climate Forcing ◽

System Model ◽

Surface Mass Balance ◽

Earth System ◽

Surface Mass

Abstract. We present a reconstruction of historical (1950–2014) surface mass balance (SMB) of the Greenland ice sheet (GrIS) using a high-resolution regional climate model (RACMO2; ∼11 km) to dynamically downscale the climate of the Community Earth System Model version 2 (CESM2; ∼111 km). After further statistical downscaling to 1 km spatial resolution, evaluation using in situ SMB measurements and remotely sensed GrIS mass change shows good agreement. Comparison with an ensemble of previously conducted RACMO2 simulations forced by climate reanalysis demonstrates that the current product realistically represents the long-term average and variability of individual SMB components and captures the recent increase in meltwater runoff that accelerated GrIS mass loss. This means that, for the first time, climate forcing from an Earth system model (CESM2), which assimilates no observations, can be used without additional corrections to reconstruct the historical GrIS SMB and its recent decline that initiated mass loss in the 1990s. This paves the way for attribution studies of future GrIS mass loss projections and contribution to sea level rise.

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Surface mass balance downscaling through elevation classes in an Earth system model: application to the Greenland ice sheet

The Cryosphere ◽

10.5194/tc-13-3193-2019 ◽

2019 ◽

Vol 13 (12) ◽

pp. 3193-3208 ◽

Cited By ~ 5

Author(s):

Raymond Sellevold ◽

Leonardus van Kampenhout ◽

Jan T. M. Lenaerts ◽

Brice Noël ◽

William H. Lipscomb ◽

...

Keyword(s):

Mass Balance ◽

Regional Climate ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Earth System Model ◽

System Model ◽

Lapse Rate ◽

Surface Mass Balance ◽

Earth System ◽

Surface Mass

Abstract. The modeling of ice sheets in Earth system models (ESMs) is an active area of research with applications to future sea level rise projections and paleoclimate studies. A major challenge for surface mass balance (SMB) modeling with ESMs arises from their coarse resolution. This paper evaluates the elevation class (EC) method as an SMB downscaling alternative to the dynamical downscaling of regional climate models. To this end, we compare EC-simulated elevation-dependent surface energy and mass balance gradients from the Community Earth System Model 1.0 (CESM1.0) with those from the regional climate model RACMO2.3. The EC implementation in CESM1.0 combines prognostic snow albedo, a multilayer snow model, and elevation corrections for two atmospheric forcing variables: temperature and humidity. Despite making no corrections for incoming radiation and precipitation, we find that the EC method in CESM1.0 yields similar SMB gradients to RACMO2.3, in part due to compensating biases in snowfall, surface melt, and refreezing gradients. We discuss the sensitivity of the results to the lapse rate used for the temperature correction. We also evaluate the impact of the EC method on the climate simulated by the ESM and find minor cooling over the Greenland ice sheet and Barents and Greenland seas, which compensates for a warm bias in the ESM due to topographic smoothing. Based on our diagnostic procedure to evaluate the EC method, we make several recommendations for future implementations.

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Greenland Surface Mass Balance as Simulated by the Community Earth System Model. Part I: Model Evaluation and 1850–2005 Results

Journal of Climate ◽

10.1175/jcli-d-12-00615.1 ◽

2013 ◽

Vol 26 (20) ◽

pp. 7793-7812 ◽

Cited By ~ 39

Author(s):

Miren Vizcaíno ◽

William H. Lipscomb ◽

William J. Sacks ◽

Jan H. van Angelen ◽

Bert Wouters ◽

...

Keyword(s):

Mass Balance ◽

Climate Models ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Earth System Model ◽

System Model ◽

Surface Mass Balance ◽

Earth System ◽

Surface Mass ◽

Community Earth System Model

Abstract The modeling of the surface mass balance (SMB) of the Greenland Ice Sheet (GIS) requires high-resolution models in order to capture the observed large gradients in the steep marginal areas. Until now, global climate models have not been considered suitable to model ice sheet SMB owing to model biases and insufficient resolution. This study analyzes the GIS SMB simulated for the period 1850–2005 by the Community Earth System Model (CESM), which includes a new ice sheet component with multiple elevation classes for SMB calculations. The model is evaluated against observational data and output from the regional model Regional Atmospheric Climate Model version 2 (RACMO2). Because of a lack of major climate biases, a sophisticated calculation of snow processes (including surface albedo evolution) and an adequate downscaling technique, CESM is able to realistically simulate GIS surface climate and SMB. CESM SMB agrees reasonably well with in situ data from 475 locations (r = 0.80) and output from RACMO2 (r = 0.79). The simulated mean SMB for 1960–2005 is 359 ± 120 Gt yr−1 in the range of estimates from regional climate models. The simulated seasonal mass variability is comparable with mass observations from the Gravity Recovery and Climate Experiment (GRACE), with synchronous annual maximum (May) and minimum (August–September) and similar amplitudes of the seasonal cycle. CESM is able to simulate the bands of precipitation maxima along the southeast and northwest margins, but absolute precipitation rates are underestimated along the southeastern margin and overestimated in the high interior. The model correctly simulates the major ablation areas. Total refreezing represents 35% of the available liquid water (the sum of rain and melt).

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Present-day and future Greenland Ice Sheet precipitation frequency from CloudSat observations and the Community Earth System Model

The Cryosphere ◽

10.5194/tc-14-2253-2020 ◽

2020 ◽

Vol 14 (7) ◽

pp. 2253-2265

Author(s):

Jan T. M. Lenaerts ◽

M. Drew Camron ◽

Christopher R. Wyburn-Powell ◽

Jennifer E. Kay

Keyword(s):

Climate Models ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Earth System Model ◽

System Model ◽

Earth System ◽

Precipitation Frequency ◽

Worst Case ◽

Rainfall Frequency ◽

Community Earth System Model

Abstract. The dominant mass input component of the Greenland Ice Sheet (GrIS) is precipitation, whose amounts and phase are poorly constrained by observations. Here we use spaceborne radar observations from CloudSat to map the precipitation frequency and phase on the GrIS, and we use those observations, in combination with a satellite simulator to enable direct comparison between observations and model, to evaluate present-day precipitation frequency in the Community Earth System Model (CESM). The observations show that substantial variability of snowfall frequency over the GrIS exists, that snowfall occurs throughout the year, and that snowfall frequency peaks in spring and fall. Rainfall is rare over the GrIS and only occurs in regions under 2000 m elevation and in the peak summer season. Although CESM overestimates the rainfall frequency, it reproduces the spatial and seasonal variability of precipitation frequency reasonably well. Driven by the high-emission, worst-case Representative Concentration Pathway (RCP) 8.5 scenario, CESM indicates that rainfall frequency will increase considerably across the GrIS, and will occur at higher elevations, potentially exposing a much larger GrIS area to rain and associated meltwater refreezing, firn warming, and reduced storage capacity. This technique can be applied to evaluate precipitation frequency in other climate models and can aid in planning future satellite campaigns.

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Regional grid refinement in an Earth system model: impacts on the simulated Greenland surface mass balance

The Cryosphere ◽

10.5194/tc-13-1547-2019 ◽

2019 ◽

Vol 13 (6) ◽

pp. 1547-1564 ◽

Cited By ~ 9

Author(s):

Leonardus van Kampenhout ◽

Alan M. Rhoades ◽

Adam R. Herrington ◽

Colin M. Zarzycki ◽

Jan T. M. Lenaerts ◽

...

Keyword(s):

Mass Balance ◽

Climate Model ◽

Regional Climate ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Earth System Model ◽

System Model ◽

Surface Mass Balance ◽

Earth System ◽

Surface Mass

Abstract. In this study, the resolution dependence of the simulated Greenland ice sheet surface mass balance (GrIS SMB) in the variable-resolution Community Earth System Model (VR-CESM) is investigated. Coupled atmosphere–land simulations are performed on two regionally refined grids over Greenland at 0.5∘ (∼55 km) and 0.25∘ (∼28 km), maintaining a quasi-uniform resolution of 1∘ (∼111 km) over the rest of the globe. On the refined grids, the SMB in the accumulation zone is significantly improved compared to airborne radar and in situ observations, with a general wetting (more snowfall) at the margins and a drying (less snowfall) in the interior GrIS. Total GrIS precipitation decreases with resolution, which is in line with best-available regional climate model results. In the ablation zone, CESM starts developing a positive SMB bias with increased resolution in some basins, notably in the east and the north. The mismatch in ablation is linked to changes in cloud cover in VR-CESM, and a reduced effectiveness of the elevation classes subgrid parametrization in CESM. Overall, our pilot study introduces VR-CESM as a new tool in the cryospheric sciences, which could be used to dynamically downscale SMB in scenario simulations and to force dynamical ice sheet models through the CESM coupling framework.

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