Reduction of Near-Inertial energy through the dependence of wind stress on the Ocean-Surface velocity

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Rath, Willi, Greatbatch, Richard John, Zhai, Xiaoming
• Format: Article in Journal/Newspaper
• Language: English
• Published: AGU (American Geophysical Union) 2013
• Subjects: Southern Ocean
• Online Access: https://oceanrep.geomar.de/id/eprint/21143/; https://oceanrep.geomar.de/id/eprint/21143/1/Rath_et_al_2013_JGR_Oceans.pdf; https://oceanrep.geomar.de/id/eprint/21143/7/rath_greatbatch_zhai13.pdf; https://doi.org/10.1002/jgrc.20198

A realistic primitive-equation model of the Southern Ocean at eddying spatial resolution is used to examine the effect of ocean-surface-velocity dependence of the wind stress on the strength of near-inertial oscillations. Accounting for the ocean-surface-velocity dependence of the wind stress leads to a large reduction of wind-induced near-inertial energy of approximately 40 percent and of wind power input into the near-inertial frequency band of approximately 20 percent. A large part of this reduction can be explained by the leading-order modification to the wind stress if the ocean-surface velocity is included. The strength of the reduction is shown to be modulated by the inverse of the ocean-surface-mixed-layer depth. We conclude that the effect of surface-velocity dependence of the wind stress should be taken into account when estimating the wind-power input into the near-inertial frequency band and when estimating near-inertial energy levels in the ocean due to wind forcing.