Impact of current-wind interaction on vertical processes in the Southern Ocean

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Song, Hajoon, Marshall, John C., McGillicuddy, Dennis J., Seo, Hyodae
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2020
• Subjects: Southern Ocean; Eddy-wind interaction; Ekman pumping; Stratification; Eddy kinetic energy; Mixed layer depth; Curl; Drake Passage
• Online Access: https://hdl.handle.net/1912/25926

Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 125(4), (2020): e2020JC016046, doi:10.1029/2020JC016046. Momentum input from westerly winds blowing over the Southern Ocean can be modulated by mesoscale surface currents and result in changes in large‐scale ocean circulation. Here, using an eddy‐resolving 1/20 degree ocean model configured near Drake Passage, we evaluate the impact of current‐wind interaction on vertical processes. We find a reduction in momentum input from the wind, reduced eddy kinetic energy, and a modification of Ekman pumping rates. Wind stress curl resulting from current‐wind interaction leads to net upward motion, while the nonlinear Ekman pumping term associated with horizontal gradients of relative vorticity induces net downward motion. The spatially averaged mixed layer depth estimated using a density criteria is shoaled slightly by current‐wind interaction. Current‐wind interaction, on the other hand, enhances the stratification in the thermocline below the mixed layer. Such changes have the potential to alter biogeochemical processes including nutrient supply, biological productivity, and air‐sea carbon dioxide exchange. The MITgcm can be obtained online (http://mitgcm.org). The geostrophic current product derived from the sea level anomaly can be downloaded in the Copernicus Marine and Environment Monitoring Service of Ssalto/Duacs gridded “allsat” series and along‐track Sea Level Anomalies, Absolute Dynamic Topographies and Geostrophic velocities over the Global Ocean, Mediterranean Sea, Black Sea, European Seas and Acrtic Ocean areas, in Delayed‐Time and in Near‐Real‐Time. Resources supporting this work were provided by the NASA High‐End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center with the award number SMD‐15‐5752. H. S., J. ...