WHOI PO

Title: "Near-inertial wave propagation in a curved front"

Abstract: In this work, we study the effect of flow curvature, or angular momentum, on the propagation and trapping characteristics of near-inertial waves (NIWs) in a curved front. The curved front is idealized as a baroclinic vortex in cyclo-geostropic balance. Motivated by ocean observations, we employ a Gaussian base flow, which by construction possesses a shield of oppositely-signed vorticity surrounding its core, and we consider both cyclonic and anticyclonic representations of this flow. Following two main assumptions, i.e. that the (a) horizontal wavelength of the NIW is smaller than the length scale of the background flow (the WKBJ approximation), and (b) the vertical wavelength of the NIW is smaller than the radial distance of interest,we derive the NIW dispersion relation and discuss the group velocity and direction of energy propagation. We show that the curvature can (i)increase the critical depth and horizontal extent of the trapping region, (ii) reduce NIW activity at the center of the anticyclonic vortex core and enhance it in the cyclonic shield surrounding the core for high curvatures, (iii)lead to NIW trapping  in the anticyclonic shield surrounding the cyclonic core, and (iv) increase the available band of NIW frequencies that are trapped. The solutions from the ray-tracing method are supported by numerical solutions of the governing equations linearized about the cyclo-geostrophic base-state. Finally, these methods are applied to an idealized model of oceanic mesoscale Arctic eddies showing an increase in the critical depth of trapping. We plan to investigate the fate of IGWs in curved fronts further with idealized three-dimensional simulations.