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

Area of Science:

• Earth System Science
• Climate Modeling
• Glaciology

Background:

• Spinning up complex Earth system models (ESMs) is computationally intensive.
• Interactive ice sheet components pose unique challenges due to long equilibration timescales and feedback processes.

Purpose of the Study:

• To present a computationally tractable, iterative procedure for spinning up complex ESMs with interactive ice sheets.
• To demonstrate a faster and more cost-effective method for initializing climate and ice sheet simulations.

Main Methods:

• An iterative procedure alternating between fully coupled and data-atmosphere configurations.
• Periodic regeneration of atmospheric forcing to maintain realistic model state evolution.
• Demonstration using the Community Earth System Model Version 2 (CESM2) coupled to the Community Ice Sheet Model Version 2 (CISM2) over Greenland.

Main Results:

• The iterative spin-up procedure was successfully applied to initialize the preindustrial climate in CESM2-CISM2 over Greenland.
• The resulting equilibrium climate state closely matched a traditional spin-up simulation with a prescribed ice sheet.
• The method proved to be faster and computationally cheaper than conventional approaches.

Conclusions:

• The iterative method offers a significant improvement in efficiency for spinning up complex ESMs, including those with interactive ice sheets.
• This approach facilitates the development of initial conditions for transient simulations, such as those for CMIP6.
• The technique is broadly applicable to ESMs with or without interactive ice sheet components.