Will High-Resolution Global Ocean Models Benefit Coupled Predictions on Short-Range to Climate Timescales?

TitleWill High-Resolution Global Ocean Models Benefit Coupled Predictions on Short-Range to Climate Timescales?
Publication TypeJournal Article
Year of Publication2018
Date Published01/2018
Abstract / Summary

As the importance of the ocean in the weather and climate system is increasingly recognized, operational systems are now moving towards coupled prediction not only for seasonal to climate timescales but also for short-range forecasts. A three-way tension exists between the allocation of computing resources to refine model resolution, the expansion of model complexity/capability, and the increase of ensemble size. Here we review evidence for the benefits of increased ocean resolution in global coupled models, where the ocean component explicitly represents transient mesoscale eddies and narrow boundary currents. We consider lessons learned from forced ocean/sea-ice simulations; from studies concerning the sea surface temperature (SST) resolution required to impact atmospheric simulations; and from coupled predictions. Impacts of the mesoscale ocean in western boundary current regions on the large-scale atmospheric state have been identified. Understanding of air-sea feedback in western boundary currents is modifying our view of the dynamics in these key regions. It remains unclear whether variability associated with open ocean mesoscale eddies is equally important to the large-scale atmospheric state. We include a discussion of what processes can presently be parameterized in coupled models with coarse resolution non-eddying ocean models, and where parameterizations may fall short. We discuss the benefits of resolution and identify gaps in the current literature that leave important questions unanswered.

DOI10.1016/j.ocemod.2017.11.002
Year of Publication: 2018
Date Published: 01/2018

As the importance of the ocean in the weather and climate system is increasingly recognized, operational systems are now moving towards coupled prediction not only for seasonal to climate timescales but also for short-range forecasts. A three-way tension exists between the allocation of computing resources to refine model resolution, the expansion of model complexity/capability, and the increase of ensemble size. Here we review evidence for the benefits of increased ocean resolution in global coupled models, where the ocean component explicitly represents transient mesoscale eddies and narrow boundary currents. We consider lessons learned from forced ocean/sea-ice simulations; from studies concerning the sea surface temperature (SST) resolution required to impact atmospheric simulations; and from coupled predictions. Impacts of the mesoscale ocean in western boundary current regions on the large-scale atmospheric state have been identified. Understanding of air-sea feedback in western boundary currents is modifying our view of the dynamics in these key regions. It remains unclear whether variability associated with open ocean mesoscale eddies is equally important to the large-scale atmospheric state. We include a discussion of what processes can presently be parameterized in coupled models with coarse resolution non-eddying ocean models, and where parameterizations may fall short. We discuss the benefits of resolution and identify gaps in the current literature that leave important questions unanswered.

DOI: 10.1016/j.ocemod.2017.11.002
Citation:
Hewitt, HT, MJ Bell, EP Chassignet, A Czaja, D Ferreira, SM Griffies, P Hyder, JL McClean, AL New, and MJ Roberts.  2018.  "Will High-Resolution Global Ocean Models Benefit Coupled Predictions on Short-Range to Climate Timescales?"  https://doi.org/10.1016/j.ocemod.2017.11.002.