Climate Dynamics
EPS 231
(Spring 2009)
Instructor:
Eli Tziperman,
TF: Dorian
Abbot, abbot at
fas.harvard.edu
Day, time & location: M. 2:304:00, Th., 2:304;
Location: Geological Museum, 4th floor, room 418. 24 Oxford
St. Cambridge.
Announcements Last updated: April 16, 2009.
We'll have class this Wednesday, March 18, 56:30.
No class on Thursday March 19.
We'll also have class Wednesday April 1st, 56:30.
No class Monday March 30.
Feel free to write or call me with any questions:
Office hours: please write/ call.
Detailed teaching notes and links to source
materials, Matlab codes and
more
Homework:
HWEBM1, due Thursday Feb 12
HWENSO1, due Monday March 2
HWENSO2, due Monday March 9
HWENSO3, due Monday March 16
HWENSO+THC, due Wednesday April 1st
HWCON1
due April 23,
The basics of climate dynamics, from the feedbacks that maintain the
mean climate to phenomenology and mechanisms of climate variability.
We will cover energy balance models, climate equilibria and stability
with examples from equable climate to snowball earth. Examples of
climate variability to be covered are El Nino (occurring roughly every
4 yrs), the thermohaline circulation and its multiple equilibria and
variability (decadal and longer); thermohaline variability as a
possible explanation for the medieval warm period and the little ice
ate (hundreds of years); the DansgaardOeschger warming
events observed in the Greenland ice core (every 1500 yr), Heinrich
events involving massive collapses of ice during glacial times (every
710,000yr) and glacialinterglacial variability (100,000 yr). In
each case, we will discuss physical mechanisms and demonstrate them
with a hierarchical modeling approach, from toy models to GCMs.
Needed background in nonlinear dynamics will be covered.
Familiarity with some basic Geophysical Fluid Dynamics (the equivalent
of MIT 12.800, or Harvard EPS 131, EPS 132 or EPS 232), or general
fluid dynamics (e.g. engineering fluid courses at Harvard) will be
assumed. The course may be taken as a sequel to Harvard's Physics of
Climate (EPS 208), or MIT's Climate Physics and Chemistry (12.842),
but can also be taken independently of that course.
Course homepage: http://www.seas.harvard.edu/climate/eli/Courses/EPS231/2009spring/
First lecture (ppt),
A detailed outline of the lectures, and a complete list of reference
materials used in each lecture is available
here.
 Outline and motivation.
 Basic climate feedbacks. Supporting material
may be found here.
 radiation, energy balance, albedo, ice, clouds
 climate stability, budykosellers model, snowball.
 El Nino  Southern Oscillation
(Cessi et al., 2001);
additional supporting material may be found
here.
 Phenomenology: basics: Gill atmosphere; reduced gravity
models, equatorial ocean waves (Dijkstra, 2000),
(Gill, 1982).
 Coupled oceanatmosphere dynamics, demonstrated via the
CaneZebiak model
 Delayed oscillator
 ENSO regimes: fast SST, fast wave, mixed; recharge oscillator:
 Irregularity: chaos
 Irregularity: stochastic forcing, non normal dynamics, optimal
initial conditions and stochastic optimals
 Westerly wind bursts
 Locking to seasonal cycle
 Atmospheric teleconnections
 Equable climate lecture additional supporting
material may be found here.
 Thermohaline circulation
(Dijkstra, 2000); additional
supporting material may be found here.
 Phenomenology, mixed boundary conditions, Stommel model
 Advective and convective feedbacks; flip flop and loop
oscillations.
 Stability, bifurcations and multiple equilibria
 Stochastic forcing; linear vs nonlinear; non normal dynamics,
noise induced transitions between steady states
 Thermohaline flushes (``deep decoupling'' relaxation
oscillations)
 Zonally averaged models and closures to 2d models.
 Atmospheric feedbacks
 D/O and Heinrich events: supporting material
may be found here.
 DO:THC flushes vs sea ice changes;
 Heinrich events: bingepurge oscillator, climatic effects,
synchronous collapses
 Glacial cycles: supporting material
may be found here.
 Phenomenology
 Milankovitch forcing
 Energy balance atmosphere
 Ice sheets: mass balance, geometry, parabolic profile.
 Glaciology basics: Glenn's law, basic solutions equilibrium
profiles of ice sheets and ice shelves.
 Simple models of glacial cycles
 Phase locking to Milankovitch forcing
Homework assignments are 50% of final grade, and a final course
project will constitute the remaining 50%. There is an option to
take this course as a pass/fail with approval of instructor. If
interested, you need to obtain this approval during the first three
weeks of the course.

Cessi, P., Pierrehumbert, R., and Tziperman, E. (2001).
 Lectures on enso, the thermohaline circulation, glacial cycles and
climate basics.
In Balmforth, N. J., editor, Conceptual Models of the Climate.
Woods Hole Oceanographic Institution.

Dijkstra, H. A. (2000).
 Nonlinear physical oceanography.
Kluwer Academic Publishers.

Gill, A. E. (1982).
 AtmosphereOcean Dynamics.
Academic Press, Inc, San Diego, CA, 662pp.

Hartmann, D. (1994).
 Global Physical Climatology.
Academic press, San Diego.