Increasing model resolution improves but overestimates global mid-depth circulation simulation.

Area of Science:

• Oceanography
• Climate Modeling
• Geophysics

Background:

• Climate models with increased spatial resolution have enhanced upper-layer ocean circulation simulation.
• Accurate reproduction of mid-depth ocean circulation by high-resolution models remains uncertain.

Purpose of the Study:

• To evaluate the performance of climate models with varying resolutions in simulating mid-depth ocean circulation.
• To assess the impact of model resolution on current speed, flow direction, and temporal variations.

Main Methods:

• Analysis of 17 climate models with different spatial resolutions.
• Comparison of model outputs with observational data for current speed and direction.
• Evaluation of the representation of mesoscale processes in varying-resolution models.

Main Results:

• Both low and high-resolution models generally underestimate current speeds compared to observations.
• High-resolution models show improved simulation of current speed and flow direction, with exceptions in the Southern Ocean.
• Model resolution enhances the representation of temporal variations and mesoscale processes, but leads to an average 65% overestimation of their intensity.

Conclusions:

• Increasing model resolution improves mid-depth ocean circulation simulation, particularly in regions with strong currents.
• Despite improvements, challenges remain in accurately simulating current speeds globally and flow direction in specific regions like the Southern Ocean.
• High-resolution models better capture dynamic processes but require adjustments to avoid overestimating mesoscale activity intensity.