Towards high-fidelity simulations of coastal submesoscale baroclinic instabilities with MPAS–O (vE3SM3.0.0) – Part 2: Realistic experiments
- 1Los Alamos National Laboratory (Los Alamos, United States of America)
Abstract
River plumes can strongly influence coastal dynamics but are poorly represented in global ocean models due to stringent resolution requirements. Following the idealized simulations presented in a companion paper (Hinson et al., 2026), this study presents submesoscale-permitting realistic simulations using unprecedented regional refinement with MPAS–O. We assess MPAS–O's ability to represent river plume dynamics by comparing with a validated ROMS configuration focused on the Mississippi–Atchafalaya (M–A) plume in the northern Gulf of Mexico (GoM). The variable-resolution mesh spans 1.4 km in the GoM to 100 km in the Pacific and Indian Oceans. We incorporate several improvements to the representation of river forcing in MPAS–O: the pseudo point source treatment of runoff, river temperature prescribed from air temperature, and passive tracers to track freshwater transport. MPAS–O generates vigorous submesoscales in the open GoM, as quantified by probability density functions of surface relative vorticity and divergence. While the model qualitatively captures the M–A plume's seasonal evolution, it does not realistically reproduce the summer submesoscale eddy field on the Texas–Louisiana shelf. A persistent brackish lens associated with reduced vertical mixing forms and is present throughout the M–A plume. We hypothesize that this arises from interacting parameterization and structural design choices within MPAS–O that affect plume stratification and instability growth under realistic forcing, rather than from deficiencies in numerics. Our results demonstrate MPAS–O's potential for simulating submesoscale processes in the open ocean while highlighting challenges in using regional refinement to model coastal dynamics.
Versions
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BibTeX
@article{schlichting2026towards,
title = {{Towards high-fidelity simulations of coastal submesoscale baroclinic instabilities with MPAS–O (vE3SM3.0.0) – Part 2: Realistic experiments}},
author = {Dylan R. Schlichting and Katherine M. Smith and Mark R. Petersen and Robert D. Hetland and Kyle E. Hinson and Darren Engwirda},
journal = {Geoscientific Model Development},
year = {2026},
month = oct,
doi = {10.5194/gmd-19-9627-2026},
url = {https://gmd.copernicus.org/articles/19/9627/2026/},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Towards high-fidelity simulations of coastal submesoscale baroclinic instabilities with MPAS–O (vE3SM3.0.0) – Part 2: Realistic experiments
AU - Dylan R. Schlichting
AU - Katherine M. Smith
AU - Mark R. Petersen
AU - Robert D. Hetland
AU - Kyle E. Hinson
AU - Darren Engwirda
PY - 2026
DA - 2026/10/12
JO - Geoscientific Model Development
DO - 10.5194/gmd-19-9627-2026
UR - https://gmd.copernicus.org/articles/19/9627/2026/
AB - River plumes can strongly influence coastal dynamics but are poorly represented in global ocean models due to stringent resolution requirements. Following the idealized simulations presented in a companion paper (Hinson et al., 2026), this study presents submesoscale-permitting realistic simulations using unprecedented regional refinement with MPAS–O. We assess MPAS–O's ability to represent river plume dynamics by comparing with a validated ROMS configuration focused on the Mississippi–Atchafalaya (M–A) plume in the northern Gulf of Mexico (GoM). The variable-resolution mesh spans 1.4 km in the GoM to 100 km in the Pacific and Indian Oceans. We incorporate several improvements to the representation of river forcing in MPAS–O: the pseudo point source treatment of runoff, river temperature prescribed from air temperature, and passive tracers to track freshwater transport. MPAS–O generates vigorous submesoscales in the open GoM, as quantified by probability density functions of surface relative vorticity and divergence. While the model qualitatively captures the M–A plume's seasonal evolution, it does not realistically reproduce the summer submesoscale eddy field on the Texas–Louisiana shelf. A persistent brackish lens associated with reduced vertical mixing forms and is present throughout the M–A plume. We hypothesize that this arises from interacting parameterization and structural design choices within MPAS–O that affect plume stratification and instability growth under realistic forcing, rather than from deficiencies in numerics. Our results demonstrate MPAS–O's potential for simulating submesoscale processes in the open ocean while highlighting challenges in using regional refinement to model coastal dynamics.
SN - 1991-9603
ER -