An Efficient Ice Sheet/Earth System Model Spin-up Procedure for CESM2-CISM2

An Efficient Ice Sheet/Earth System Model Spin-up Procedure for CESM2-CISM2: Description, Evaluation, and Broader Applicability

Lofverstrom, Marcus (University of Arizona; National Center for Atmospheric Research)
Fyke, Jeremy G. (University of Colorado; Associated Engineering Group Ltd.)
Thayer-Calder, Katherine (National Center for Atmospheric Research)
Muntjewerf, L. (TU Delft Physical and Space Geodesy)
Vizcaino, M. (TU Delft Physical and Space Geodesy)
Sacks, William J. (National Center for Atmospheric Research)
Lipscomb, William H. (National Center for Atmospheric Research)
Otto-Bliesner, Bette L. (National Center for Atmospheric Research)
Bradley, S.L. (TU Delft Physical and Space Geodesy; University of Sheffield)

2020

Spinning up a highly complex, coupled Earth system model (ESM) is a time consuming and computationally demanding exercise. For models with interactive ice sheet components, this becomes a major challenge, as ice sheets are sensitive to bidirectional feedback processes and equilibrate over glacial timescales of up to many millennia. This work describes and demonstrates a computationally tractable, iterative procedure for spinning up a contemporary, highly complex ESM that includes an interactive ice sheet component. The procedure alternates between a computationally expensive coupled configuration and a computationally cheaper configuration where the atmospheric component is replaced by a data model. By periodically regenerating atmospheric forcing consistent with the coupled system, the data atmosphere remains adequately constrained to ensure that the broader model state evolves realistically. The applicability of the method is demonstrated by spinning up the preindustrial climate in the Community Earth System Model Version 2 (CESM2), coupled to the Community Ice Sheet Model Version 2 (CISM2) over Greenland. The equilibrium climate state is similar to the control climate from a coupled simulation with a prescribed Greenland ice sheet, indicating that the iterative procedure is consistent with a traditional spin-up approach without interactive ice sheets. These results suggest that the iterative method presented here provides a faster and computationally cheaper method for spinning up a highly complex ESM, with or without interactive ice sheet components. The method described here has been used to develop the climate/ice sheet initial conditions for transient, ice sheet-enabled simulations with CESM2-CISM2 in the Coupled Model Intercomparison Project Phase 6 (CMIP6).

Community Earth System Model version 2 (CESM2)
Coupled ice-sheet/Earth system modeling
Interactive ice sheets
Spin-up simulation

http://resolver.tudelft.nl/uuid:30c04c9a-e769-4787-a226-5c6a2bc554f8

https://doi.org/10.1029/2019MS001984

1942-2466

Journal of Advances in Modeling Earth Systems, 12 (8), 1-23

Institutional Repository

journal article

© 2020 Marcus Lofverstrom, Jeremy G. Fyke, Katherine Thayer-Calder, L. Muntjewerf, M. Vizcaino, William J. Sacks, William H. Lipscomb, Bette L. Otto-Bliesner, S.L. Bradley