Mid-Summer observations of water column physical properties and circulation in the San Jorge Gulf (Patagonian Shelf)

Abstract

In this study, we present detailed insights into the mid-summer density field and flow patterns within the San Jorge Gulf (Patagonian Shelf of Argentina). Utilizing unique data acquired from a towed undulating vehicle equipped with a Conductivity-Temperature-Depth (CTD) sensor and a hull-mounted acoustic Doppler current profiler (ADCP), we investigate the spatial distribution and temporal evolution of the density structure and associated currents. Our observations reveal the presence of a distinctive bottom dome-like structure comprised of dense, cold, and saline waters in the central basin of the gulf during mid-summer. Analysis of the flow dynamics indicates the presence of a near-geostrophic flow regime sustaining this dense water feature. Furthermore, our study highlights the significant role of ageostrophic velocities, primarily influenced by the modulation of pycnocline thickness by M₂+M₄ internal tides. These findings contribute to a deeper understanding of the oceanographic processes governing the mid-summer dynamics in the San Jorge Gulf, shedding light on the interaction between density structures and associated currents. Such insights are essential for advancing our knowledge of coastal ocean circulation and its implications for various ecological and environmental phenomena.