E4.1 BISICLES-E3SM

Abstract

As an ES3M NGD project, we are coupling the BISICLES ice sheet model into E3SM, along with the appropriate verification testing and initialization needed to make it a reliable and useful addition to E3SM.  As one of the dynamical cores developed by the PISCEES and ProSPect SciDAC Application Partnerships, the BISICLES model is a natural fit with the E3SM project for many reasons.

Built on the SciDAC-supported Chombo framework, BISICLES uses block-structured adaptive mesh refinement (AMR) to dynamically and adaptively deploy very fine spatial resolution where needed to accurately resolve the dynamics of features like grounding lines and ice streams. Recent work by Cornford, Martin, et al (2016) demonstrated that very fine (sub-km) resolution is essential to accurately resolve the dynamics of the marine ice sheets which dominate the West Antarctic Ice Sheet. Without such fine resolution, models may compute solutions which are qualitatively and quantitatively incorrect.  Uniformly resolving the entire Antarctic ice sheet at such fine resolution would be prohibitively expensive, with an enormous amount of unnecessary computational effort. Because the fine resolution must follow grounding lines as they retreat over hundreds of kilometers, BISICLES is an ideal tool for investigating the response of the Antarctic Ice sheet to marine forcing and the consequent grounding-line retreat and contribution to sea level rise (SLR). AMR enables the required resolution while also maintaining a reasonable time to solution.

As a first step toward understanding the coupled ice-ocean system, the POP2X ocean model has been coupled to BISICLES to form the POPSICLES coupled model.  Ground-breaking POPSICLES simulations of the entire Southern ocean and full continental Antarctic Ice sheet demonstrated the importance of fully-coupled models in understanding the response of the coupled ice-ocean system, while also exposing the difficulty of such simulations.

We expect that adding BISICLES to E3SM will enhance E3SM’s predictive capability for understanding the role of ice sheets in the fully-coupled climate system and the resulting contributions to SLR, while also providing a useful companion to the in-development MALI model for V&V purposes.

We will draw on our previous experience coupling BISICLES to CISM and to POP, while leveraging the significant progress already made toward coupling the MALI model. Once that is done, we will test the coupled model to ensure that it is robust and correct, develop the approaches necessary to initialize the BISICLES ice sheet model in the E3SM context, and make these initial conditions and test cases available to the E3SM community.