Radiative Processes in Planetary Atmospheres

ATOC/ASTR 5560      Fall 2001      Syllabus

Meeting Time:   Mon & Wed   3:00-3:50   Duane G131   Fri   2:00-5:00   Stadium 136
Instructor:   Frank Evans   Duane D317   492-4994   evans@nit.colorado.edu
Office Hours:   Wed 9-11   Thu 1-3   (or call, email, or drop by)

Description:  This course will cover the basic physics of, and computational methods for, the interaction of visible and infrared radiation with the gases and particles in planetary atmospheres. The applications will be mainly in the role radiation plays in determining planetary temperature structure and in climate change. The emphasis will be on the Earth's atmosphere. Topics include:

Required Text: An Introduction to Atmospheric Radiation, Liou, 2001 (in press).
Recommended: Radiative Transfer in the Atmosphere and Ocean, Thomas & Stamnes, 1999.
  Atmospheric Radiation: Theoretical Basis, Goody and Yung, 1989.
  Atmospheric Radiative Transfer, Lenoble, 1993.
  Atmospheric Transmission, Emission, and Scattering, Kyle, 1991.
  Absorption and Scattering of Light by Small Particles, Bohren and Huffman, 1983.
  Radiation and Cloud Processes in the Atmosphere, Liou, 1992.
  Remote Sensing of the Lower Atmosphere: An Introduction, Stephens, 1994.

Prerequisites: ASTR 5110 or ATOC 5225; ATOC 5235 (Remote Sensing) or radiative transfer experience is recommended; computer programming experience will be useful.

   25%   Computational labs
   25%   Homework
   30%   Tests (2)
   20%   Project

Format of the course:

I will not be lecturing in the traditional sense of presenting all the course material for you to absorb in class. Instead I will put the week's lecture notes on the class Web site by the previous Friday. Students will be expected to read the notes, and hopefully some of the assigned text reading, for the Monday and Wednesday classes. On Monday and Wednesday I'll review the notes, answer questions, and work examples with the class. Towards the end of some Wednesdays we'll have practice problem solving in groups. You should bring a calculator and your notes to every class.

Most Fridays we will have a computational laboratory in the ATOC Weather Lab (Stadium 136). Radiative transfer is a computational science in that almost no real world calculations are done without computer models. The purpose of the labs will be to obtain hands on experience in running radiative models and to learn the underlying physics by graphing and explaining the model results.


There will be 11 computational labs on Fridays. You should be able to complete the lab work in the two to three hour lab period. The lab results and answers to questions will be due the following Friday.

There will be homework assignments handed out about every two weeks and due one week later. You may get help on the homework, but what you turn in must be your own work. Late homework will be accepted, but the grade will be reduced.

There will be two written tests during the semester, but no final exam. These tests will be about two hours in length and will be scheduled later (probably mid October and late November).

A research project in atmospheric radiation is required in lieu of a final exam. The project must include using a radiative transfer model in a well defined study. Some examples are modeling to interpret surface flux data, developing a Monte Carlo radiative transfer model for inhomogeneous atmospheres, modeling to develop a remote sensing inversion algorithm, and using a radiative convective equilibrium model to determine a planetary response to various radiative forcings. You will describe the objectives, methods, and results in a poster presentation during the final exam period.

Outline of Topics

Part I:
Introduction to Radiative Transfer
Radiative definitions
Absorption, emission, and Planck functions
Radiative transfer equation
Simple radiative transfer solutions
Part II:
Radiation and Gases
Temperature structure and gas composition profiles
Rotational and vibrational molecular transitions
Absorption line shapes and broadening mechanisms
Absorption line intensities
Atmospheric absorption spectrum
Line-by-line models
Integrated single line transmission; random band models
The k - distribution and correlated k-distribution methods
Clear sky longwave radiative transfer
Heating rates: calculation and results
Weighting functions and the cooling to space approximation
Part III:
Radiation and Particles
Particle size distributions
Cross sections and phase functions
Polarization of radiation
Rayleigh scattering
Mie scattering (method and results for aerosols and water droplets)
Index of refraction of materials
Discrete Dipole Approximation
Geometric optics scattering
Part IV:
Radiative Transfer with Scattering
Radiative transfer equation with scattering of sunlight
First order scattering
Eddington and two-stream approximate methods
Delta scaling of the radiative transfer equation
Discrete ordinates solution methods
Principle of interaction; doubling-adding method
Surface reflection: Lambertian, Fresnel, general BRDF
Plane-parallel radiative transfer results
3D radiative transfer: Monte Carlo method and results
Part V:
Radiative Equilibrium and Atmospheric Applications
Sun-Earth geometry and solar insolation; solar measurements
Earth's radiative energy budget and measurement
Radiative Equilibrium:
   Gray models (single layer and profile)
   Non gray models, the atmospheric window
   1D radiative convective equilibrium; temperature structure
Radiative forcing and climate feedbacks
Cloud radiation interactions
Aerosols radiative forcing
Greenhouse gas warming
Planetary applications