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ATM S 545 The General Circulation of the Atmosphere

Spring Quarter 2001

Instructor: J.M. Wallace
Phone: 543-7390
Office: 4909 25th NE
Email: wallace@atmos.washington.edu

Synopsis

Partitioning of global fields into zonal mean versus eddy and time mean versus transient components. Concept of available potential energy and the kinetic energy cycle as formulated by Lorenz. Balance requirements for angular momentum, energy and mass as formulated by Starr. Dynamics of the zonally symmetric component of the general circulation. Distinction between Eulerian and Lagrangian mean circulations. The Eliassen Palm flux. Energetics and life cycle of baroclinic waves, and their interaction with the background flow. Maintenance of the climatological mean circulation. Structure and dynamics of low-frequency fluctuations about the climatological mean.

Rationale

The course
  1. describes the major global wind systems and the dynamical processes that maintain them
  2. applies the quasi-geostrophic equations and other basic dynamical formalisms taught in dynamics courses to phenomena in the real atmosphere;
  3. introduces some of the techniques commonly used in diagnosing global observations and climate simulations; and
  4. offers a historical overview of the development of our current ideas concerning the nature and theory of the general circulation.
It is best taken as a sequel to ATMS 541, but is designed to be comprehensible to students with limited background in atmospheric dynamics who wish to gain an an appreciation of the role of the atmospheric general circulation in climate and the long range transport of trace substances.

Course Format

Lectures: the style is informal and questions and comments are invited. Students are evaluated on the basis of midterm and final exams (15 and 30%, respectively), a ~2500-wd. term paper (40%), and three relatively short problem sets (15%). An extensive set of course notes is provided and students are encouraged to read a set of influential journal articles.

Tentative Schedule by Week

  1. Overview, kinetic energy cycle, space/time averaging formulation
  2. Angular momentum balance, role of eddy fluxes, inference of mean meridional circulations
  3. Total energy balance as a function of latitude, role of eddy fluxes in the poleward transport of energy, inference of the mean meridional circulations, diagnosis of the hydrologic cycle
  4. Dynamics of the zonally symmetric component of the general circulation: role of eddy forcing and mean meridional circulations, potential vorticity flux and transience, application to stratospheric sudden warmings
  5. Eulerian vs, Lagrangian mean meridional circulations; Eliassen-Palm fluxes
  6. Diagnosis of time-mean flow including the climatological-mean planetary waves and the monsoons
  7. Baroclinic waves: structure, energetics, life cycle, interaction with the zonally symmetric flow
  8. Low frequency atmospheric variability: blocking, teleconnections, EOF's
Spring 2001
Updated March 19, 2001