The Role of Biologically-Generated Turbulence in the Upper Ocean
Abstract
Our interests are in oceanic processes that contribute to stirring and mixing to understand their impact on larger scales so that better sub-grid scale parameterizations may be implemented. This includes phenomena ranging from the microscale (1 cm) up to the mesoscale (10-100 km). Work on ocean biosphere energetics suggests that schooling marine organisms might generate turbulent dissipation rates with as much as 1 TW available globally to generate ocean turbulence. Measurements in Saanich Inlet revealed intense (10(exp -5) to 10(exp -4) W kg(exp -1)) turbulent bursts coinciding with the dusk vertical migration of a dense krill swarm consisting of up to 10(exp 4) individuals m(exp -3) (0.1% by volume). Lasting only 10-15 minutes, this event was nevertheless of sufficient intensity to increase daily average mixing by 2-3 orders of magnitude. This mechanism could be important for mixing nutrients and gases through the transition layer at the base of the surface mixed-layer. But turbulence dissipation does not always arise in association with migration of backscatter layers and mixing is not always associated with elevated dissipation. We seek to establish whether swimming marine organisms can contribute significantly to ocean mixing by determining the following: (1) how frequently vertically migrating backscatter layers generate turbulence and turbulent mixing; and (2) under what conditions (season, cloud-cover, lunar cycle, backscatter intensity, backscatter migration speed, etc). We have also been asked to participate in the Lateral Mixing DRI where we will map dye spreading and characterize the internal wave and turbulence conditions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2009
- Accession Number
- ADA527297
Entities
People
- Eric Kunze
- John Dower
- Richard Dewey
Organizations
- University of Victoria