- Outline and motivation.
- Basics: Continuum hypothesis, pressure, hydrostatics
(Ku 1.4-1.5, p 4; 1.7 p 9-11). Kinematics: Eulerian vs
Lagrangian, material derivative, stream line (Ku 3.1-3.4 p
50-56), stream function (Ku 3.13, p 69-70). Continuity
equation (mass conservation, Kn, Box 4.1 p 69), temperature
equation (conservation of heat, Kn, Box 4.2 p 74-75).
Equation of state. Ocean: the overturning ocean
circulation and the vertical temperature profile in the ocean,
solar radiation and air-sea heat fluxes (Ku p 39-61).
- Momentum equations: acceleration, pressure force, gravity,
friction, Coriolis force (Kn, chapter 5, p 80-107; for
Coriolis, a better source is Ku section 4.12 p 99-101).
Atmosphere/ ocean: geostrophy (Kn p 110), thermal
wind, problem of the ``level of no motion'', weather systems and
pressure highs and lows/ ocean gyres and ocean surface height.
- Density, potential temperature, potential density, sigma theta,
sigma-4 , stability, Brunt Vaisala frequency (OU p 230-232;
Kn p 29-34, 38) and buoyancy oscillations(*), T-S diagrams
and mixing of water masses (OU p 225-229), T-S distribution
(Kn p 163-183).
- Rossby number, inertial oscillations (Kn p 108-109),
equations and circular trajectories of fluid parcels(*).
- Friction: molecular, turbulent, horizontal vs vertical friction
in the ocean (Kn p 98-101); bottom friction
parameterization (Kn p 97); scale selective vs non scale
selective friction; inertial motions with friction (Kn p
120);
- Combined effects of friction, wind and rotation: shear stress
(Kn p 100), wind speed and wind stress, balance of friction
and rotation in mixed layer, Ekman transport (Kn p
122-123); why don't icebergs move downwind? Coastal upwelling,
fisheries and El Nino (OU p 133-137, 153-155);
- Mid term review: which terms in the Navier Stokes equations are
responsible for: inertial motions, damped inertial motions,
geostrophy, Ekman layers/ drift, buoyancy oscillations, hydrostatic
balance. In temperature equation: abyssal recipes.
- Ekman pumping (Kn p 128); Ekman spiral, (Kn p
124); curl tau from observations; North Atlantic subtropical and sub
polar gyres; beta v=f dw/dz (Kn, p XX); Sverdrup balance
(beta v = curl tau).
- f=f(y), beta=df/dy, momentum and vorticity equations for a
simple linear, shallow water/ barotropic, time dependent, bottom
friction, rotating case (Kn p 128-131). Vorticity
examples: solid body rotation and f as a ``planetary vorticity'';
irrotational vortex (Ku p 125); Sverdrup balance as a
vorticity balance.
- Idealized ocean basic and calculating v from the Sverdrup
balance and then u. The western boundary current problem. Balance
between friction and beta term: only possible physical solution is
at west. Heuristic vorticity explanation of western boundary
currents (Kn p 131-133; OU, p 85-98).
- Surface ocean waves (Kn 192-198): vector vorticity,
irrotational flow (vorticity=0, velocity=gradient of potential);
Bernoulli function (simple linearized version) and boundary
conditions on velocity potential; wave solution in 2d (x,z) and
dispersion relation; limits of shallow and deep ocean; particle
trajectories; phase and group velocities; dimensional arguments for
deep and shallow gravity wave dispersion relations. Tsunamis as
shallow waves, waves refraction when approaching a curved beach.
Other waves mentioned briefly: internal waves, Poincare waves,
coastal and equatorial Kelvin waves, Rossby waves and a heuristic
explanation of westward propagation.
- Practicalities: using Matlab, solving a simple
advection-diffusion numerically: leap frog, center space
differencing, Robert Filter.
- Ian's El Nino
lecture.
- Thermohaline circulation: phenomenology, mean state, present-day
variability; different atmospheric response and surface boundary
conditions for Temperature and salinity; driving by T, breaking by
S; paleo climate perspective: introduction to paleo climate
variability, proxies, ice cores and sediment cores; THC during LGM,
possible variability during Heinrich and D/O events; advective
instability feedback; THC flushes; Stommel two box model and
multiple equilibria. Some misc slides that were presented in class
(only a few slides in each of these files):
1,
2,
3
Beginning texts:
- G. L. Pickard and W. J. Emery, Descriptive Physical Oceanography
- An Introduction, Butterworth Heinemann, 1990,
- Stephen Pond and George L. Pickard, Introductory dynamical
Oceanography, 3rd edition, Butterworth-Heinemann, 1993,
Intermediate texts:
- Philander, S. G. H., El Niño, La Niña, and the Southern
Oscillation., Academic Press, 1990,
- Benoit Cushman-Roisin, Introduction to geophysical fluid
dynamics, Prentice-Hall, 1995,
Advanced texts:
- Pedlosky, J., 1987, Geophysical Fluid Dynamics., 2nd edition,
Springer-Verlag
- Pedlosky, J., 1996, ocean circulation theory, Springer-Verlag,
Berlin-Heidelberg-New York.
- Pedlosky, J., 2003, waves in the ocean and atmosphere.,
Springer-Verlag, Berlin-Heidelberg-New York.
- Gill, A. E, 1982, Atmosphere-ocean dynamics, Academic Press,
London
Homework will be given throughout the course. The best 80% of the
homework will constitute 40% of the final grade. Each student will be
invited to present a brief informal description of some aspects of the
ocean circulation and its role in climate (20%), see details
here
for a list of possible
subjects. The final exam will be a take home (40%).
Introduction to physical oceanography
