Ballooning of Surface-Advected Freshwater Bulge in a Rotating Frame

Abstract

This research delves into the intrinsic dynamics of an anticyclonic circulation that involves a ballooning bulge generated by a generalized river plume over an idealized shelf topography. The circulation features a strong jet-stream overshooting the estuary mouth, curving toward the coast, and a returning flow along the shoreside edge. Our study focuses on the ballooning process, which involves the jet-stream’s expansion and the freshwaters’ downstream movement. We demonstrate that the negative curvature vorticity, generated by flow inertia, sustains this process by amplifying the jet-stream through anticyclonic gradient wind balance. Our research presents new insights into the origin of the negative curvature vorticity associated with the anticyclonic bending of the jet-stream. The negative curvature vorticity regulates the ration between streamline’s and trajectory's radius, promoting the freshwaters’ escape from the jet-stream and facilitating the bulge’s ballooning. The negative shear vorticity over the downshelf coast near the estuary mouth is the source of the curvature vorticity. The banking and curvature-acceleration processes, which stand for the cross-stream variation of the downstream component of the pressure force and the turning of the jet-stream, respectively, trade-off this shear vorticity to form the negative curvature vorticity.