Evaluation of preCICE (version 3.3.0) in an Earth System Model Regridding Benchmark

TL;DR

This study evaluates preCICE v3.3.0 on a benchmark originally used to assess ESM-specific regridding tools, demonstrating that a general-purpose coupler can achieve comparable accuracy with appropriate pre- and post-processing. By implementing NP and RBF mappings (with a partition-of-unity approach) and converting geodesic ESM meshes to Cartesian coordinates, the work shows that RBF mappings outperform traditional second-order methods on most smooth test functions, while NN remains competitive. The paper documents substantial preprocessing needs when adapting a general-purpose tool to ESM-style benchmarks and discusses the implications for cross-domain knowledge transfer and future performance comparisons with ESMincluding potential refinements to the benchmark. Overall, the results highlight the practical viability of preCICE for ESM regridding, with notable gains from RBF methods and a clear pathway for integrating cross-domain coupling approaches into Earth system simulations.

Abstract

In Earth System Modeling (ESM), meshes of different models usually do not match, requiring data mapping algorithms implemented in coupling software. Valcke et al. recently introduced a benchmark to evaluate such algorithms and compared implementations in four specialized ESM couplers. In this paper, we assess preCICE, a general-purpose coupling library not limited to ESM, using this benchmark and compare our results to the original study. The generality of preCICE with its larger community offers potential benefits to ESM applications, but the software naturally lacks ESM-specific solutions. We describe necessary pre- and postprocessing steps to make the benchmark tangible for preCICE. Overall, preCICE achieves comparable results; using its radial basis function mapping yields significantly lower errors.

Figures (10)

• Figure 1: Lon/lat representation of nogt mesh with all test functions: a) sinusoid b) harmonic c) vortex d) gulfstream
• Figure 2: Mesh conversion process using a section of the ATM mesh icos and the SEA mesh nogt. a) icos, node-based b) icos, node-based & triangulated c) nogt, node-based & triangulated & with mask d) icos, node-based & triangulated & mapped nogt mask e) icos, like d) with overlayed cell centers for each sea cell f) icos, like e) with added connectivity information for cell centers
• Figure 3: Substeps to add connectivity to meshes. From top to bottom: (i) calculation of plane basis vectors and normal, (ii) sorting of nodes around the cell center using normal and respective angles, (iii) result of Delaunay triangulation of nodes expressed in plane basis vectors
• Figure 4: Malformed torc mesh around south pole. Torc mesh mask with missing cells in white (left) and resulting error on bggd mesh in cells not masked out correctly (right).
• Figure 5: Malformed torc mesh in northern Africa. Torc mesh mask (left) and resulting error on bggd mesh (right).