Improved global maps and 54‐year history of wind‐work on ocean inertial motions

The global distribution and 54‐year time dependence of the energy‐flux from the wind to near‐inertial motions is computed by driving a slab mixed‐layer model with NCEP/NCAR Reanalysis winds, improving upon previous estimates [ Alford , 2001 ; Watanabe and Hibiya , 2002 ]. The slab model is solved spectrally with frequency‐dependent damping. The resulting solutions are more physically sensible than the previous, and more skillful at high latitudes, where the inertial frequency approaches the 4×‐daily sampling of the Reanalysis winds. This enables Alford's calculation, whose domain was limited to ±50°, to be extended to the poles. The high‐latitude reliability is demonstrated by direct comparison with a high‐resolution regional model (REMO) in the NE Atlantic. The total power input, 0.47 TW, has increased by 25% since 1948, paralleling observed increases in extratropical cyclone frequency and intensity. If believable, the trend may have important consequences for modulation of the meridional overturning circulation.