About

Background

Small coastal embayments are ubiquitous features of eastern boundary upwelling systems like the California Current System and play a disproportionately large role in local ecosystem dynamics. In these upwelling bays, persistent and sharp nearshore thermal fronts form downstream of coastal topographic features. Due to their small scales, these fronts are dominated by submesoscale dynamics and likely play a key role modulating cross-shelf exchange. Small upwelling bays offer a unique opportunity to study the dynamics of submesoscale fronts in the coastal ocean because their formation is predictably linked to topographic features.

Study site

This project is targeted in San Luis Obispo Bay in central California, a small embayment whose length scale is on the order of the local Rossby deformation radius, where previous research from our team has revealed the presence of a persistent and narrow temperature front, strong convergence of surface currents, and impacts on local hypoxia and harmful algal bloom (HAB) development.

Approach

This study integrates high-resolution field observations and numerical modeling to explore the links between submesoscale fronts, turbulent mixing, and bay-ocean exchange.

Scientific Goals

• Test scalings for cross-front transport and examine the potentially important role of nonlinear dynamics.
• Examine the role of the diurnal seabreeze in the interaction between submesoscale fronts and turbulence in the nearshore.
• Investigate how geostrophic adjustment during frontal decay impacts bottom boundary layer dynamics, retention of bottom water, and connectivity of surface water, processes which are relevant to hypoxia and larval dispersal.