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Title: Implementation of the Jacobian-free Newton-Krylov method for solving the for solving the first-order ice sheet momentum balance

Journal Article · · Journal of Computational Physics
OSTI ID:1018601
 [1];  [2];  [3];  [3];  [4];  [5];  [5]
  1. Sandia National Laboratories (SNL)
  2. ORNL
  3. New York University
  4. University of Bristol, UK
  5. Los Alamos National Laboratory (LANL)

We have implemented the Jacobian-free Newton-Krylov (JFNK) method for solving the rst-order ice sheet momentum equation in order to improve the numerical performance of the Community Ice Sheet Model (CISM), the land ice component of the Community Earth System Model (CESM). Our JFNK implementation is based on signicant re-use of existing code. For example, our physics-based preconditioner uses the original Picard linear solver in CISM. For several test cases spanning a range of geometries and boundary conditions, our JFNK implementation is 1.84-3.62 times more efficient than the standard Picard solver in CISM. Importantly, this computational gain of JFNK over the Picard solver increases when rening the grid. Global convergence of the JFNK solver has been signicantly improved by rescaling the equation for the basal boundary condition and through the use of an inexact Newton method. While a diverse set of test cases show that our JFNK implementation is usually robust, for some problems it may fail to converge with increasing resolution (as does the Picard solver). Globalization through parameter continuation did not remedy this problem and future work to improve robustness will explore a combination of Picard and JFNK and the use of homotopy methods.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Sciences (NCCS)
Sponsoring Organization:
USDOE Office of Science (SC)
DOE Contract Number:
DE-AC05-00OR22725
OSTI ID:
1018601
Journal Information:
Journal of Computational Physics, Vol. 230, Issue 17; ISSN 0021-9991
Country of Publication:
United States
Language:
English