Linear and Nonlinear Stratified Spindown over Sloping Topography
Abstract
Ocean bottom boundary layers are regions adjacent to topography where turbulence mixes heat, momentum and biogeochemical tracers. These regions serve as a dynamical control on the circulation by dissipating energy and shape the local characteristics of the marine environment by redistributing tracers. Tracers, such as sediment and nutrients, are transported by the lateral circulation near the bottom as well as the vertical circulation into and out of these layers. In order to quantify these momentum and tracer fluxes, an understanding of the strength and structure of this circulation is needed. Friction plays an important role in driving this lateral and vertical circulation. The boundary exerts a frictional stress on the flow that reduces the near bottom velocity within a frictional boundary layer, the Ekman layer. This frictional force induces an ageostrophic Ekman flow down the pressure gradient through a subinertial balance between the frictional force, the Coriolis acceleration, and the horizontal pressure gradient. The vertically-integrated Ekman flow, the Ekman transport, is directed to the right (left) of the frictional force in the Northern (Southern) Hemisphere. Convergences and divergences in the Ekman transport eject fluid out of, Ekman pumping, or inject fluid into, Ekman suction, the boundary layer. This process drives an ageostrophic secondary circulation that can accelerate or decelerate the geostrophic flow in the interior.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2010
- Accession Number
- ADA519626
Entities
People
- Jessica A. Benthuysen
Organizations
- Massachusetts Institute of Technology