ATM S 542 - Spring 2005

Spring 2005: ATMS 542

Balance Dynamics

(still listed as "Synoptic and Mesoscale Dynamics")

MWF 12:30-1:20, Room ATG 310C

Instructor: Professor Dale Durran

606 ATG, 543-7440, durrand@atmos.washington.edu
Office hours: Monday 3:00-4:00, Wednesday 3:00-4:00

Useful Texts:

Holton, J.R., 2004: Introduction to Dynamic Meteorology, 4th Edition. (Textbook errata.)
Gill, A.E., 1982: Atmosphere Ocean Dynamics.
Pedlosky, J., 1998: Geophysical Fluid Dynamics, 2nd Edition.

Overview: The purpose of the course is to

Systematically explore "balance" approximations to derive physical understanding of extratropical circulations.
Understand instabilities of large-scale atmospheric flows.
Explore the simplicity, power and limitations of dynamics determined solely by potential vorticity

Quizzes and Final Exam

Quizzes (25 minutes each) Nominally April 8, 22 and May 6, 20.

Final: Tuesday June 7th 10:30-12:30

Homework

Problem Set 1: Due April 11

Problem Set 2: Due April 22

Problem Set 3: Due May 11

Problem Set 4: Due June 1 temps300mb.gif

Course Outline

Introduction: Atmospheric Motions in the Extratropical Troposphere

Prof. Hakim's Power-Point Survey

Governing Equations, Scaling and Simplifications

Summary and review of basic equations
PE equations is pseudoheight coordinates
Nondimensionalizing the PE equations

Properties of Linear PE Modes

Rossby waves
Gravity waves
Internal gravity wave animation (f=0 case)

Derivation of the QG Equations

Potential Vorticity Dynamics

Conservation
Inversion
Tropopause maps (generated by Greg Hakim)
Tropopause Figures

Unstable Normal-Modes in Parallel Shear Flow: Baroclinic Instability

The Eady Model
Eady Model Figures (courtesy of Greg Hakim)
- Growth rates
- Phase speeds
- Neutral modes
- Growing/decaying modes
- Unstable Eady wave growing from random initial perturbations (linear QG simulation, one x-wavenumber, random initial amplitudes of all continuous spectrum modes, the growing and the decaying mode)
- Localized initial perturbation, meridonially concentrated jet (nonlinear QG simulation)
- Downstream development (localized initial perturbation, nonlinear QG simulation)

Unstable Normal-Modes in Parallel Shear Flow: Barotropic Instability

Aspects of "Generalized" stability (non-modal growth)

Grading: Quizes (4) 25% total, Final 35%, Homework 40%.

No makeup tests will be provided unless excused in advance.