Ballooning of Surface‐Advected Freshwater Bulge in a Rotating Frame

Abstract

AbstractThis 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.