Deep ocean inertia-gravity waves simulated in a high-resolution global coupled atmosphere-ocean GCM

In order to investigate the deep ocean inertia-gravity waves, a high-resolution global coupled atmosphere-ocean simulation is carried out with a coupling interval of 20 minutes. Large (similar to 10(-3) m s(-1)) root-mean-square variability of vertical velocity is found in middepths (2000-4000 m), which is not reported in previous studies using realistic ocean simulations. Horizontal distribution of the large variability roughly corresponds to the wintertime atmospheric storm tracks and is stretched equatorward due to beta-dispersion in open ocean with some "shadow regions'' behind the obstacles. Frequency spectrum of vertical velocity has strong peaks at around f and 2f (f is the local inertial period) in midlatitudes, and has additional peak at around (3/2) f or 3f at some points. These results suggest necessity of re-evaluation of wind-induced near-inertial energy with high-frequency atmospheric forcing.