Fig. 1.
Infrared image of a cyclonic cold-core eddy, located near the island of Santa Catalina, California, as described in Marmorino et al. (2018). Temperature range is approximately 1 °C and spatial resolution is 3 m. Indicated are the eddy thermal perimeter (1); a sector of warm inflow (2); small-scale cold patches (3); and areas of persistent banding (4, 5).
Fig. 2.
(a) A model of the vertical profile of the BV-frequency N(z) in the ocean. The layer 0 < z < h 1 represents the thermocline, which has a maximum BV-frequency N 1 ≫ N 2. (b) An idealized perturbation to the thermocline (at z = 0), having a vertical displacement and characteristic horizontal scale a. The perturbation is shown moving to the left at velocity V.
Fig. 3.
Wave number curves relating wave number components and of the wave number vector of stationary internal waves generated by a horizontally moving (to the left) source with speed V. (a) Case of the thin stably stratified layer with inside the deep water ( ). (b) Case of the stably stratified layer in the shallow water ( and ).
Fig. 4.
Calculation of constant phase lines for different m = 1, 2,…, 10 at some time t, when the source was at the origin, and the ten wave crests shown here were radiated by the source at previous times. (a) The case when the horizontal dimensions of the source =30-100 m, and the directions of the propagation of wave crests with respect to the direction of the source velocity lie in the interval (b) The horizontal dimension =10 m, and the interval of -directions is
Fig. 5.
Diagram of transition from rectangular coordinate system (x,y) to the local curvilinear coordinate system near the perimeter of the circle.
Fig. 6.
Spiral-like wave phase lines behind a point source at arbitrary moment in two cases: (a) V = 0.3 m/s, a = 10 m, Froude number F = 0.39, (b) V = 0.15 m/s, a = 10 m, F = 0.195, Case (a) is a better match to field observations (see Fig. 7), and in this case the wave source has traveled 5 km in 4.63 h, or 1.6 revolutions. Over time, the source together with the entire pattern of phase lines behind it rotates in a counterclockwise circle with velocity V.
Fig. 7.
Overlay of calculated phase lines (from Fig. 6a) on the infrared image from Fig. 1. The spiraling phase lines resemble the shape and wavelength of the banded structures in the image.