Trapping of the near‐inertial wave wakes of two consecutive hurricanes in the Loop Current

The near-inertial trapping of the wave wakes of two consecutive hurricanes at the base of the Loop Current is described using observations of a triangular mooring array. Hurricane Gustav translates over the Loop Current twice as fast and leads to a sharper, but equally strong, wind intensity peak than Hurricane Ike. Following the passage of Gustav, near-inertial oscillations in the main thermocline have large horizontal (similar to 34045km) and vertical (similar to 850m) scales. The wave kinetic energy propagates down with a vertical group velocity of several tens of meters per day and leads to a downward energy flux of [1.82-7.10]x10(-3)Wm(-2). Observations suggest that the dispersion of the wave wakes produced by the hurricanes is driven by Doppler shifting in the upper similar to 600m and the vertical-varying vorticity inside the Loop Current. Near-inertial kinetic energy is enhanced and near-inertial oscillations are circularly polarized in a critical layer at the base of the Loop Current where the group velocity vector is nearly horizontal. The trapping and amplification of the near-inertial wave wakes of two consecutive hurricanes is addressed using a primitive equation numerical model. Numerical results suggest an increase of the near-inertial kinetic energy and vertical shear by a factor of similar to 2 near the critical layer due to wave-mean flow and wave-wave interactions. A K-profile parameterization of these interactions results in banded regions of elevated turbulent kinetic energy dissipation rates of E[0.5-6.6]x10(-6)Wm(-3) for critical Richardson number Ri(c)=1, depending on the stratification of the water column.