Global statistics of inertial motions

Statistics of inertial currents in the North Pacific, North Atlantic, and Southern Ocean are derived for the period 1997-2003 from surface trajectories of Argo profiling floats by employing a method developed recently by Park et al. (2004). The distribution of inertial amplitudes is non-Gaussian in the range 0∼80 cm/sec with an average value of 13.7 cm/sec. The inertial amplitude in the mid-latitude (30°∼45°N band exceeds those in both the low (15°∼30°N) and high (45°∼60°N) latitude bands. In three basins, the amplitude in summer is greater than that in winter by 15%∼25%. The inertial energy in the mixed layer reaches approximately 1100 J/m²∼1165 J/m² globally. The spatiotemporal patterns of inertial amplitudes in the North Atlantic mostly depend on the MLD, which exhibits strong meridional gradients. However, the small meridional gradient of the MLD in the North Pacific does not contribute significantly to the spatial distribution of inertial amplitudes. The total inertial energy estimated from the floats is consistent with the theory that inertial energy could contribute significantly to sustaining the meridional overturning circulation.