SHiELD-MOM6: High-Resolution Coupled Atmosphere-Ocean Modeling

Sep 26, 2025

What I developed

  • The coupling framework connecting SHiELD, MOM6, and SIS2 through FMS
  • Exchange-grid infrastructure for conservative flux exchange between components
  • High-resolution coupled atmosphere-ocean-ice model configurations
  • Evaluation of hurricane-ocean interaction, including Hurricane Helene (2024)

Motivation

Air-sea interactions drive storm intensity and ocean response. This coupled system captures two-way feedback between the atmosphere and ocean at kilometer scales, enabling accurate simulations of hurricane-ocean interactions and coastal impacts.

Overview

We present a new high-resolution coupled atmosphere-ocean model, SHiELD-MOM6, which integrates GFDL’s advanced atmospheric model, the System for High-resolution modeling for Earth-to-Local Domain (SHiELD), the Modular Ocean Model version 6 (MOM6), and the Sea Ice Simulator (SIS2).

The model leverages the Flexible Modeling System (FMS) coupler and its innovative exchange grid to enable a robust and scalable two-way interaction between the atmosphere and ocean. The atmospheric component is built on the non-hydrostatic Finite-Volume Cubed-Sphere Dynamical Core (FV3) with the latest version of the SHiELD physics parametrization suite, while the ocean component is the latest version of MOM, supporting kilometer-scale high-resolution and regional applications.

Coupling infrastructure

The SHiELD-MOM6 model employs the Flexible Modeling System (FMS) coupler, which facilitates the exchange of information between the atmospheric and oceanic components. The exchange grid ensures accurate and efficient communication, enabling the two-way interaction necessary for realistic coupled simulations.

Schematic of a one-dimensional exchange grid and communication map between the atmosphere and ice components at different resolutions. The red sides of the arrow indicate the step where variables are projected from the exchange grid. The light-blue and mauve sides of the arrows represent the projection of variables onto the exchange grid from the atmosphere or ice components, respectively.
Schematic of a one-dimensional exchange grid and communication map between the atmosphere and ice components at different resolutions. The red sides of the arrow indicate the step where variables are projected from the exchange grid. The light-blue and mauve sides of the arrows represent the projection of variables onto the exchange grid from the atmosphere or ice components, respectively.

Hurricane Helene (2024)

Validation is demonstrated through a suite of experiments, including idealized hurricane simulations and a realistic North Atlantic case study featuring Hurricane Helene 2024. The animation below shows the simulated sea level pressure and 10 m winds (left) alongside the sea surface temperature anomaly and ocean surface currents (right) as the storm crosses the Gulf.

Hurricane Helene (2024): sea level pressure and surface winds (left); sea surface temperature change and ocean currents (right). The cold wake and upwelling behind the storm are captured by the two-way coupling.

Scalability

Scalability tests have been conducted to evaluate the model’s performance on massively parallel computing systems. The results demonstrate that SHiELD-MOM6 maintains high computational efficiency as the number of processors increases, ensuring that high-resolution coupled simulations can be performed within practical timeframes

Strong scaling (a) and weak scaling (b): actual speedup/efficiency (red circles) compared to ideal speedup/efficiency (black squares) as a function of the number of PEs.
Strong scaling (a) and weak scaling (b): actual speedup/efficiency (red circles) compared to ideal speedup/efficiency (black squares) as a function of the number of PEs.

Key results

  • Air-sea interactions are effectively captured, both in storm intensity and structure and in the ocean response.
  • The coupling reproduces ocean phenomena such as storm-induced upwelling, the cold wake, and sea level changes.
  • Scalability tests confirm the model’s computational efficiency on massively parallel systems.

This work establishes a unified, modular cornerstone for advancing high-resolution coupled modeling, with significant implications for weather forecasting and climate research.

Reference

Mouallem, J., Gao, K., Reichl, B. G., Chilutti, L., Harris, L., Benson, R., Zadeh, N., Chen, J., Chen, J.-H., and Zhang, C.: Development of a high-resolution coupled SHiELD-MOM6 model – Part 1: Model overview, coupling technique, and validation in a regional setup, Geoscientific Model Development, 18(18), 6461-6478, 2025. https://doi.org/10.5194/gmd-18-6461-2025

Coupled Modeling SHiELD MOM6 FV3 HPC
Joseph Mouallem
Joseph Mouallem
Computational Scientist & Research Software Engineer

Publications

Development of a high-resolution coupled SHiELD-MOM6 model – Part 1: Model overview, coupling technique, and validation in a regional setup
A new high-resolution coupled atmosphere-ocean model, SHiELD-MOM6, integrating SHiELD, MOM6 and SIS2 through the FMS coupler and its exchange grid.
Joseph Mouallem, Kun Gao, Brandon G. Reichl, Lauren Chilutti, Lucas Harris, Rusty Benson, Niki Zadeh, Jing Chen, Jan-Huey Chen, Cheng Zhang
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