Course Details
Subject {L-T-P / C} : ER5506 : Dynamics of Ocean { 3-1-0 / 4}
Subject Nature : Theory
Coordinator : Prof. Naresh Krishna Vissa
Syllabus
Dynamics: Scales of motion, introduction to non-dimensional numbers. Stability of fluid column: vertical acceleration in fluids and criteria for static stability, double diffusion and dynamic stability. The equation of motion in oceanography: obtaining solutions to the equations, including boundary conditions, the derivation of the terms in the equation of motion, coordinate systems. The equation of continuity of volume: the concept of continuity of volume,the derivation of the equation of continuity of volume, an application of the equation of continuity. The non-linear terms in the equation of motion, scaling and the Reynolds Number, Reynolds stresses, equations for the mean or average flow, Reynolds stresses and eddy viscosity, scaling the equations of motion Rossby number, Ekman number, effects of rotation.
Currents without friction geostrophic flow: hydrostatic equilibrium, inertial motion, geopotential, geopotential surfaces and isobaric surfaces, the geostrophic equation, the geostrophic method for calculating relative velocities, an alternative derivation of the geostrophic equation, the thermal wind equations, relations between isobaric and level surfaces, comments on geostrophic currents.
Currents with friction winddriven circulation: Nansen's qualitative argument, the equation of motion with friction included, Ekman's solution to the equation of motion with friction present, comments on the experimental observations used by Ekman, transport and upwelling—the effect of boundaries, upwelling and downwelling away from boundaries, bottom friction and shallow water effects, limitations of the Ekman theory, Sverdrup's solution for the wind-driven circulation, application of the Sverdrup equations, the mass transport stream function.Westward intensification—Stommel's contribution, the planetary wind field and the drag coefficient CD,Munk's solution, comments on Munk's solution. Vorticity: relative, planetary, absolute and potential. Westward intensification of ocean currents explained using conservation of vorticity.
Oceanic mesoscale eddies, formation of sub-tropical gyres, equatorial current systems, monsoonal winds and currents over the North Indian Ocean Somali current Southern Ocean - Swells.
Course Objectives
- This course is an introduction to dynamics of Ocean as it relates to oceanic flows. The focus of the course is understanding the basic concepts in fluid dynamics, such as dynamical components of the equations of motion, Lagrangian vs. Eulerian motion, vorticity dynamics, Ekman dynamics, rotating waves, basin scale circulation and quasi-geostrophic dynamics, the effects of stratification and the use of layer models, instability theory, hydraulic control, and turbulent mixing.
Course Outcomes
Students develop a knowledge on Ocean dynamics.
Essential Reading
- Pond S. and G. L. Pickard, Introductory dynamical oceanography, Butterworth-Heinemann
- Fomin L. M, Dynamic method in oceanography, Elsevier publication co
Supplementary Reading
- Reddy M. P. M, Descriptive Physical Oceanography, Oxford and IBH Publishing Company
- Stewart RH, Introduction to Physical Oceanography, Orange Grove Texts