Toward a more complete understanding of coastal upwelling dynamics

Trustees Of Boston University, Boston

Investigators

Abstract

This study will explore the widespread ocean phenomenon of coastal upwelling, in which nutrient-rich water is pumped toward the surface mainly by wind forcing on the sea surface. This phenomenon has pivotal influence on the appearance of fisheries in different parts of the world. The study will use mathematical models that represent idealized conditions for upwelling over a sloping continental shelf. Despite the idealizations, the models will add three-dimensionality aspects and dynamical effects caused by different water densities, i.e., by buoyancy. Results will be cast in a framework that includes the slope of the continental shelf, buoyancy effects and Earth’s rotation influence. As broader impacts, the study is expected to improve understanding on a process that affects dissolved and suspended materials near the coast. It also will train a postdoctoral scholar, a graduate student, and two undergraduate students. The proposal will explore three-dimensional pathways for coastal upwelling under vertically stratified ocean conditions. The study will use a series of idealized 3D numerical simulations, contrasting the customary 2D descriptions associated with Ekman dynamics. Simulations will be placed in a holistic framework that accounts for the interactions among wind-driven circulation, (sub)mesoscale turbulence, and boundary layer processes. Thus, simulations will address the coupling between surface and bottom boundary layers through a framework based on the slope Burger number, which compares buoyancy and Coriolis frequencies. The Burger number is expected to diagnose whether the onshore flow is along the bottom or in the interior of the water column. A particularity of this study, in addition to examining three-dimensional structures, is the assessment of the role of baroclinic instability in shaping the upwelling structure via eddy stirring along isopycnals. As broader impacts, this study will contribute advanced understanding of coastal upwelling, which affects dissolved and suspended matter. Also, the study will support one postdoctoral scholar, and train one graduate and two undergraduate students. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.