Description and Demonstration of the Coupled Community Earth System Model v2 – Community Ice Sheet Model v2 (CESM2‐CISM2)

Abstract Earth system/ice‐sheet coupling is an area of recent, major Earth System Model (ESM) development. This work occurs at the intersection of glaciology and climate science and is motivated by a need for robust projections of sea‐level rise. The Community Ice Sheet Model version 2 (CISM2) is th...

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Bibliographic Details
Published in:Journal of Advances in Modeling Earth Systems
Main Authors: Laura Muntjewerf, William J. Sacks, Marcus Lofverstrom, Jeremy Fyke, William H. Lipscomb, Carolina Ernani da Silva, Miren Vizcaino, Katherine Thayer‐Calder, Jan T. M. Lenaerts, Raymond Sellevold
Format: Article in Journal/Newspaper
Language:English
Published: American Geophysical Union (AGU) 2021
Subjects:
ice sheet modeling
Earth system modeling
model coupling
Physical geography
GB3-5030
Oceanography
GC1-1581
Greenland
Ice Sheet
Online Access:https://doi.org/10.1029/2020MS002356
https://doaj.org/article/283eecfb6896449aac8fb1034cf1bf0b
Description
Summary:Abstract Earth system/ice‐sheet coupling is an area of recent, major Earth System Model (ESM) development. This work occurs at the intersection of glaciology and climate science and is motivated by a need for robust projections of sea‐level rise. The Community Ice Sheet Model version 2 (CISM2) is the newest component model of the Community Earth System Model version 2 (CESM2). This study describes the coupling and novel capabilities of the model, including: (1) an advanced energy‐balance‐based surface mass balance calculation in the land component with downscaling via elevation classes; (2) a closed freshwater budget from ice sheet to the ocean from surface runoff, basal melting, and ice discharge; (3) dynamic land surface types; and (4) dynamic atmospheric topography. The Earth system/ice‐sheet coupling is demonstrated in a simulation with an evolving Greenland Ice Sheet (GrIS) under an idealized high CO2 scenario. The model simulates a large expansion of ablation areas (where surface ablation exceeds snow accumulation) and a large increase in surface runoff. This results in an elevated freshwater flux to the ocean, as well as thinning of the ice sheet and area retreat. These GrIS changes result in reduced Greenland surface albedo, changes in the sign and magnitude of sensible and latent heat fluxes, and modified surface roughness and overall ice sheet topography. Representation of these couplings between climate and ice sheets is key for the simulation of ice and climate interactions.

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