Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6388015 | Ocean Modelling | 2016 | 10 Pages |
â¢Inertial motion generated by Hurricane George in the DeSoto Canyon is analyzed.â¢Data from 13 mooring and a realistic primitive-equation model are used.â¢Strong inertial motions were present in the mixed layer in the open ocean.â¢Inertial waves trapped in an energy flux recirculation gyre around the canyon.â¢The gyre transferred 1/3 of the wind input below the mixed layer.
Hurricane Georges passed directly over an array of 13 moorings deployed in the DeSoto Canyon in the northern Gulf of Mexico on 27-28 September 1998. Current velocity data from the mooring array were analyzed together with a primitive-equation model simulation with realistic hurricane forcing, to characterize the generation and propagation of the hurricane-generated near-inertial waves. The model successfully reproduces the observed mean (sub-inertial) and near-inertial motions. The upper ocean response is strongly impacted by the canyon 'wall': a strong jet is formed along the slope, and the near-inertial motions on the shelf are rapidly suppressed. The model results moreover suggest that strong near-inertial waves in the mixed layer are mostly trapped in an energy flux recirculating gyre around the canyon. This gyre retains the near-inertial energy in the canyon region and enhances the transfer of near-inertial energy below the mixed layer. Additional simulations with idealized topographies show that the presence of a steep slope rather than the canyon is fundamental for the generation of this recirculating gyre. The near-inertial wave energy budget shows that during the study period the wind generated an input of 6.79Â ÃÂ 10-2Â Wm-2 of which about 1/3, or 2.43Â ÃÂ 10-2Â Wm-2, was transferred below the mixed layer. The horizontal energy flux into and out of the canyon region, in contrast, was relatively weak.