Modelling Jets and Vortices in the Ocean

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The objective of this research program is to develop and improve idealized models of oceanic systems and determine how biogeochemical properties are transported in a number of observationally-constrained systems of jets and vortices.  Excluding tides, jets and vortices are the most energetic features in the ocean and therefore play a crucial role in the distribution of physical and biological oceanic properties. Using recently-developed high performance computing software, the model equations will be solved numerically to resolve a wide range of length and time scales.  This will help us to understand the physical mechanisms that govern the energy transfers at or near the mesoscale. More specifically, this research program will answer a set of fundamental questions including: 1) Which properties are crucial in determining the stability of jets and vortices?  2) When instabilities develop, how do they evolve in the nonlinear regime and then saturate to achieve nonlinear equilibration?  3) As a result of the instability processes, how is energy cascaded between the various length and time scales?  4) What effect do these nonlinear processes have on the transport of physical and biogeochemical properties and therefore on the lifecycle of ecosystems? ******A variety of oceanic models are used to study large-scale oceanic flows.  The most general model that can be used to study virtually all large-scale oceanic phenomenon is the nonhydrostatic primitive equation (NH) model.  Two simplified limits of this model are the multi-layer Shallow Water (SW) and Quasi-Geostrophic (QG) models. My research group will use the QG, SW and NH models to idealize currents and determine their stability characteristics and induced transport. We will accomplish this in collaboration with several international observational oceanographers.  Four current systems of interest are the Bransifield Current, the Gulf of Oman Current, the Antarctic Slope Front  and the Beaufort Gyre. Our study of three-dimensional vortices will begin with idealized vortex structures but also observations of meddies using very fine scale data from seismic reflection techniques. A complimentary aspect of this research program is to investigate some of these physical systems coupled to either simple Nutrient-Phytoplankton-Zooplankton models or ones that contain size-structure.  This will enable us to determine how biological organisms are transported and emitted from currents and vortices and subsequently transported over great distances.**