A high-resolution physical-biogeochemical model for marine resource applications in the Northwest Atlantic (MOM6-COBALT-NWA12 v1.0)

• Main Authors: Ross, Andrew C., Stock, Charles A., Adcroft, Alistair, Curchitser, Enrique, Hallberg, Robert, Harrison, Matthew J., Hedstrom, Katherine, Zadeh, Niki, Alexander, Michael, Chen, Wenhao, Drenkard, Elizabeth J., Pontavice, Hubert, Dussin, Raphael, Gomez, Fabian, John, Jasmin G., Kang, Dujuan, Lavoie, Diane, Resplandy, Laure, Roobaert, Alizée, Saba, Vincent, Shin, Sang-Ik, Siedlecki, Samantha, Simkins, James
• Format: Text
• Language: English
• Published: 2023
• Subjects: Northwest Atlantic; Sea ice
• Online Access: https://doi.org/10.5194/gmd-2023-99; https://gmd.copernicus.org/preprints/gmd-2023-99/

We present the development and evaluation of MOM6-COBALT-NWA12 version 1.0, a 1/12° model of ocean dynamics and biogeochemistry in the Northwest Atlantic Ocean. This model is built using the new regional capabilities in the MOM6 ocean model and is coupled with the COBALT biogeochemical model and SIS2 sea ice model. Our goal was to develop a model to provide information to support living marine resource applications across management time horizons from seasons to decades. To do this, we struck a balance between a broad, coastwide domain to simulate basin-scale variability and capture cross-boundary issues expected under climate change, high enough spatial resolution accurately simulate features like the Gulf Stream separation and advection of water masses through finer-scale coastal features, and the computational economy required to run the long simulations of multiple ensemble members that are needed to quantify prediction uncertainties and produce actionable information. We assess whether MOM6-COBALT-NWA12 is capable of supporting the intended applications by evaluating the model with three categories of metrics: basin-wide indicators of the model's performance, indicators of coastal ecosystem variability and the regional ocean features that drive it, and model run times and computational efficiency. Overall, both the basin-wide and regional ecosystem-relevant indicators are simulated well by the model. Where notable model biases and errors are present in both types of indicators, they are mainly consistent with the challenges of accurately simulating the Gulf Stream separation, path, and variability: for example, the coastal ocean and shelf north of Cape Hatteras is too warm and salty and has minor biogeochemical biases. During model development, we identified a few model parameters that exerted a notable influence on the model solution, including the horizontal viscosity, mixed layer restratification, and tidal self-attraction and loading, which we discuss briefly. The computational performance of the model ...