SCOAR Coupled Modeling System

The SCOAR modeling system is a regional framework that connects the atmosphere, ocean, and surface waves. It couples WRF, ROMS, and WAVEWATCH III (WW3), with air–sea exchange calculated using COARE-based bulk-flux formulations, to investigate feedbacks that uncoupled component models cannot represent.

SCOAR

SCOAR supports interactive exchanges among the components, allowing the simulated ocean and sea state to influence the atmosphere while atmospheric forcing modifies currents, temperature, and waves. This framework is designed for questions involving:

• Ocean feedbacks to weather and regional climate through evolving SST and surface currents.
• Sea-state effects on momentum, sensible-heat, and latent-heat exchange.
• Wave–wind misalignment and nonequilibrium seas, including tropical-cyclone conditions.
• Conventional and experimental sea-state-dependent COARE bulk-flux parameterizations for momentum and heat exchange, including formulations for nonequilibrium seas and sea-spray effects.
• Mesoscale and frontal air–sea interaction, with online spatial filtering options for separating scales.
• Flexible atmosphere–ocean, atmosphere–wave, and ocean–wave coupling strategies.

Example Applications

Marine heatwaves and atmospheric rivers. Coupled ocean–atmosphere processes can shape compound extremes when marine heatwaves interact with landfalling atmospheric rivers. See Renkl et al. (2026) and the SAFARI project.

Sea state and surface drag under tropical cyclones. SCOAR supports studies of evolving sea states, wave–wind misalignment, upper-ocean cooling, and drag-coefficient behavior under extreme winds. This example shows the sea-surface temperature response beneath Typhoon Khanun (2023).

Offshore wind farms and air–sea interaction. Coupled simulations show how large offshore wind farms can modify atmospheric wakes, surface waves, upper-ocean mixing, and ocean-to-atmosphere feedbacks. See Seo et al. (2025) and Sauvage et al. (2025).

The SCOAR framework has been applied across tropical-cyclone, atmospheric-river, coastal, offshore-wind, and tropical-Pacific research. See the publication and current projects for peer-reviewed results and ongoing applications.

Brief History

SCOAR was developed at Scripps Institution of Oceanography, initially coupling the Regional Spectral Model (RSM) with ROMS (Seo et al. 2007b). At Woods Hole Oceanographic Institution, the system was extended to WRF–ROMS coupling (Seo and Yang, 2013), including applications to the Arctic atmospheric boundary layer. Putrasahan et al. (2013) introduced scale-selective interactive SST coupling, and Seo et al. (2014) later extended the feedbacks to include surface currents. Sauvage et al. (2023) incorporated WW3 coupling. SCOAR is now maintained and extended by the Seo Lab at the University of Hawaiʻi at Mānoa. See Publications for the cited studies and Presentations for oral and poster presentations.

Coupling Architecture

Software Requirements

SCOAR is the coupling layer; the component models must be downloaded, configured, compiled, and tested separately.

Quick Start

1. Clone SCOAR.

   git clone https://github.com/uh-manoa-scoar/scoar.git
   cd scoar
   

2. Install and test the component models. Build WRF, ROMS, and—when wave coupling is required—WW3 independently before connecting them through SCOAR.

3. Review the repository layout. The main coupling workflow is organized across Shell, Lib, and the main_scripts directory.

4. Select and prepare a domain. Start with the version-controlled material in Data/domains, then prepare atmosphere, ocean, and wave grids and forcing for the intended experiment.

5. Configure model paths and coupling choices. Set the component executable locations, coupling interval, exchanged variables, surface-flux option, and any online smoothing or eddy-filtering choices.

6. Run a short validation case. Confirm that each component advances, coupling files are exchanged at the expected times, fields are on the correct grids, and conservation/continuity checks are reasonable before scaling up.

7. Postprocess and compare. Use the supplied postprocess_scripts and compare coupled output with an uncoupled control and available observations.

Starter Example

This starter workflow provides a reproducible structure for a short atmosphere–ocean–wave sensitivity experiment. The forcing datasets and exact namelists must be selected for the target region, but all experiment-specific inputs should be versioned together.

For reproducibility, record the SCOAR commit, component-model versions, compiler/MPI/NetCDF environment, forcing-data sources, coupling interval, namelists, and postprocessing commands. Begin with the repository’s Tutorial_Doc and Data/domains directories.