ATOC 5060: Atmospheric Dynamics

Landsat 7 image of von Karman vorticies. As air flows over and around objects in its path, spiraling eddies, known as Von Karman vortices, may form. The vortices in this image were created when prevailing winds sweeping east across the northern Pacific Ocean encountered Alaska's Aleutian Islands. More images http://landsat.gsfc.nasa.gov/earthasart

Overview

An amount of energy from the Sun is intercepted by the Earth. While, exactly this amount of energy is ultimately radiated back to space, Earth’s, spherical shape and rotation causes local imbalance between incoming and outgoing radiation. This discrepancy gives rise to motions that ensure the radiative balance. Understanding the structure and dynamics of the atmosphere is central to forecasting weather and understanding climate.

This course aims to build on knowledge of the fundamental set of physical principles by applying them to quantitatively describe the behavior of large-scale atmospheric motions. By the end of this course we will have developed quantitative analysis of atmospheric propagation and instability of flow associated with mountain barriers, shallow water waves, large-scale baroclinic Rossby waves and gravity waves. A detailed examination of the development and energetics of mid-latitude baroclinic cyclones is perused, and the implications for the global scale circulation regime explored. We apply our understanding of atmospheric dynamics to problems of climatological significance, including tropical circulation, middle atmospheric flow, and the general circulation of the atmosphere.

Instructor: David Noone<dcn@colorado.edu>

When: Spring 2008; Tuesday 11:00-12:15 pm, Thursday 11:00-12:15 pm

Where: Duane E126

Prerequisites: ATOC 5225, ATOC 5400 or equivalent (ATOC 5050 and calculus may be OK)

Grading: Homework, projects, class reading assignments, mid-term and final exam (100%)

Office hours: After class on Tuesdays. Please email for an appointment

Textbook

Holton, J. R., An introduction of Dynamic Meteorology, Elsevier Academic Press, 4th ed., 2004.

(Much of the material is quite standard and appears in numerous good texts. Some of these will be good references in your study of this subject. )

Course outline

Material primarily from Chapter 5, 6,7-8,10, and bit of 11 and 12 of Holton, and supplemented by more advanced text and research articles.

Conservation laws, forces and atmospheric composition
Review of fluid dynamics: vorticity, balanced motion, scaling principles and the important non-dimensional numbers based on observed characteristics of large-scale and meso-scale systems.
Quasi-geostrophic assumptions, prediction and potential vorticity.
Boundary layers, friction and turbulence
Linear Waves of a rotating stratified atmosphere. Wave dispersion, group velocity, particle paths, rays and energy propagation. Physical interpretation of wave processes. The radius of deformation.
Quasi-Geostrophic dynamics: relevant scaling, the Beta plane, diagnostic and prognostic equations. Rossby waves, rays and energy propagation revisited.
Quasi-geostrophic instability theory. Baroclinic, Barotropic, and mixed instabilities. Physical interpretation of growth mechanisms and wavelength selection. Wave fluxes, energetics, and the role of eddies and waves in the general circulation.
The zonal mean circulation and the Hadley cell.
The general circulation
Equatorial Beta Plane. Kelvin, Rossby-gravity and Yanai waves.
Planetary waves, Elliasen-Palm fluxes, the role of wave critical layers.
Stratospheric circulation.

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