MPAS‐Ocean Simulation Quality for Variable‐Resolution North American Coastal Meshes

Abstract

Climate model components utilizing unstructured meshes enable variable resolution, regionally enhanced simulations within global domains. Here we investigate the relationship between mesh quality and simulation statistics using the JIGSAW unstructured meshing library and the Model for Prediction Across Scales‐Ocean (MPAS‐Ocean) with a focus on Gulf Stream dynamics. In the base configuration, the refined region employs 8 km cells that extend 400 km from the coast of North America. This coastal‐refined region is embedded within a low‐resolution global domain, with cell size varying latitudinally between 30 and 60 km. The resolution transition region between the refined region and background mesh is 600 km wide. Three sensitivity tests are conducted: (a) The quality of meshes is intentionally degraded so that horizontal cells are progressively more distorted; (b) the transition region from high to low resolution is steepened; and (c) resolution of the coastal refinement region is varied from 30 to 8 km. Overall, the ocean simulations are shown to be robust to mesh resolution and quality alterations. Meshes that are substantially degraded still produce realistic currents, with Southern Ocean transports within 0.4% and Gulf Stream transports within 12% of high‐quality mesh results. The narrowest transition case of 100 km did not produce any spurious effects. Refined regions with high‐resolution produce eddy kinetic energy and sea surface height variability that are similar to the high‐resolution reference simulation. These results provide heuristics for the design criteria of variable‐resolution climate model domains.

Global storm tide modeling with ADCIRC v55: unstructured mesh design and performance

“…4b). Super Typhoon Haiyan meteorology is described by the best-track Holland parametric vortex model (Holland, 1980) from 4 to 10 November (Fig. 4c).…”

A Scalable Semi‐Implicit Barotropic Mode Solver for the MPAS‐Ocean

“…In addition to the parallel scaling tests, we perform long-term 800 day simulations using the same grid mesh as for the strong scaling test to validate the MPAS-O with the semi-implicit barotropic mode solver. The validation criteria for the operational test case is that the semi-implicit model produces reasonable and stable, global oceanic currents relative to the already substantially validated explicit-subcycling scheme version of the MPAS-O as detailed elsewhere (Petersen et al, 2015;Reckinger et al, 2015;Golaz et al, 2019;Petersen et al, 2019;Hoch et al, 2020). Because we did not change any science in the model, we do not need to validate them independent of existing model results.…”

“…To compare the new semi-implicit and existing explicit-subcycling time stepping methods for the barotropic mode, this section is devoted to a brief review of the current complete time stepping procedure within MPAS-O. Since the existing explicit-subcycling scheme for the barotropic mode in MPAS-O is used extensively (Golaz et al, 2019;Hoch et al, 2020;Petersen et al, 2015Petersen et al, , 2019Reckinger et al, 2015), it is appropriate to use it as the computational and scientific benchmark for the semi-implicit method.…”

An Introduction to the E3SM Special Collection: Goals, Science Drivers, Development, and Analysis

“…Regional refinement meshes have been used in Phase 1 for testing atmospheric physics parameterizations for HR modeling (Tang et al, 2019) and in ocean/ice simulations over Antarctica for developing capabilities to model ice shelf-ocean interactions. Regional refinement meshes with higher resolution over North America (Hoch et al, 2020) and Antarctica will be used prominently in future simulations using E3SM v2.…”