Free Surface Effects on the Near-Inertial Ocean Current Response to a Hurricane
Shay, Lynn K.
Chang, Simon W.
Elsberry, Russell L.
MetadataShow full item record
During the passage of hurricane Frederic in 1979, four ocean current meter arrays in water depths of 100- 950 m detected both a barociinic and a depth-independent response in the near-inertial frequency band. Although the oceanic response was predominately barociinic, the hurricane excited a depth-independent component of 5-11 cm S-I. The origin and role of the depth-independent component of velocity is investigated using a linear analytical model and numerical simulations from a 17-level primitive equation model with a free surface. Both models are forced with an idealized wind stress pattern based on the observed storm parameters in hurricane Frederic. In an analytical model, the Green's function (Ko) is convolved with the wind stress curl to predict a sea surface depression of approximately 20 cm from the equilibrium position. The near-inertial velocities are simulated by convolving the slope of the sea surface depression with a second Green's function. The barotropic current velocities rotate inertially with periods shifted above the local inertial period by I %-2% and the maximum amplitude of II cm S-I is displaced to the right of the track at x = 2Rmax (radius of maximum winds). The free surface depression simulated by the primitive-equation model is also about 18-20 cm. The primitive equation model simulations indicate that the vertical mean pressure gradient excites 10-11 cm S-I depthaveraged currents atx = 3Rmax . The net divergence and convergence of the horizontal velocities induces vertical deflections of the sea surface. The spatial pattern of the barotropic amplitudes simulated by the numerical and analytical models differ by less than 2 cm S-I in the region 0 < x < 4Rmax> which suggests that the barotropic response to the passage of a moving hurricane is governed by linear processes.
Showing items related by title, author, creator and subject.
Grigsby, Stanley Holmes (Monterey, California. Naval Postgraduate School, 1975);The time dependent mixed-layer depth and temperature response of a two-layer hydrothermodynamic ocean model to a moving hurricane model was investigated. The hurricane model was that of Elsberry, Pearson, and Corgnati ...
Gough, Matt K.; Reiners, A.J.H.M.; MacMahan, Jamie H.; Howden, Stephan (AGU Publications, 2016-04-01);The inertial frequency is nearly diurnal at 308N latitude which transects the northeastern Gulf of Mexico (NeGoM). At this latitude, near-surface inertial oscillations can amplify due to resonance with diurnal wind ...
Hopkins, Charles K. (Monterey, California. Naval Postgraduate School, 1982-06);The current meter records collected at three sites in the Gulf of Mexico during the passage of Hurricane Frederic are analyzed to determine the storm-induced flow at various ocean depths, determine the associated energy ...