aATMS 749 Radiation Transfer Notes [Main Page] [Homework] [previous notes 2006, 2008, 2011]




Week 16: 8 December

Exam on Tuesday, 9 December, covering the entire semester: may bring 2 pages (8.5" x 11") of notes.

Week 15: 1 December

Read chapter 6. We'll work on applications of
blackbody radiation. Presentation for chapter 6.

We considered infrared radiative forcing by aerosol: Here are some rough notes on the subject.
Here's an article on the subject: see Eqs. 5 and 6.


Presentation for chapter 8, radiation transfer with emission, zero scattering limit, key feature is the idea of IR weighting functions.
Presentation for chapter 9, absorption by atmospheric gases.

Model set up for IR radiative transfer.

Examples and related literature

[The year the weather went wild (1977), a popular article for our area and time as well, general interest article].

IR radiation calculator: Good for illustrating radiation balance for variable greenhouse gas concentration.
Water vapor concentration calculator: To be used along with the radiation balance calculator to look at water vapor feedback.
Start with 300 ppm CO2; double the concentration and find surface temperature needed to provide the same outgoing IR as with 300 ppm.
Use the 1976 US Atmosphere, no clouds.
Radiatitive forcing: Difference of net flux (incoming - outgoing) with and without the radiative forcing agent (like C02 increase since the industrial revolution).

Week 14: 24 November

Read chapter 6. We'll work on applications of
blackbody radiation. Presentation for chapter 6.

Examples and related literature

Here's some Reno weather data to chew on and intrepret.

 

Week 13: 17 November

Finish up multiple scattering, and begin IR radiative transfer with a demonstration.
(Demonstration loosely tied to this site). Read chapter 6. We'll work on applications of
blackbody radiation. Presentation for chapter 6.

Examples and related literature

Variability of the total downwelling flux for the cloud above the ground problem.
The horizontal axis is ground albedo. The reflection coefficient for the conservative
case is R, and R + T = 1. Ttotal = T / (1 - R * Ag). Click on the image for a larger
version. The simple spread sheet for this calculation is here.

Week 12: 10 November

Tuesday, no class.

Thursday -- finish up multiple scattering, discuss questions on the HW, and begin IR radiative transfer with a demonstration.
(Demonstration loosely tied to this site).

Week 11: 3 November

We'll look at the 2 stream approximation
Primary reading material is from this classic paper on the subject.
Radiative Transfer with Multiple Scattering (presentation) we will use for this subject.
Chapter 13 is also about this subject.

Week 10: 27 October

Continue with multiple scattering, and looking at the single scattering approximation, and phase function details.
We will continue considering the general equation for radiation transfer and a few simple examples of its use on Tuesday.
Read chapter 11 and Appendix A.
Here are chapter 11 notes on the general equation for radiation transfer, phase function, and the single scattering approximation.

Then we'll look at the 2 stream approximation
Primary reading material is from this classic paper on the subject.
Radiative Transfer with Multiple Scattering (presentation) we will use for this subject.
Chapter 13 is also about this subject.

Examples and related literature

Comparison of 2 stream methods.

Ship tracks modeling and observations.

Sky observations on 29 October 2014

 

 Rayleigh Optical depth calculator we wrote a few years ago: useful for the calculation of diffuse radiation amount in the atmosphere.

Example aerosol optical depth and size distribution retrieval from the ultra clear day, 28 Oct 2014.

 

Week 9: 20 October

NOTE CHANGE: THURSDAY: Midterm exam. You can use one side of an 8.5" x 11" piece of paper for notes and equations during the exam.

TUESDAY: Begin multiple scattering. Primary reading material is from this classic paper on the subject.
Radiative Transfer with Multiple Scattering (presentation) we will use for this subject.
We will consider the general equation for radiation transfer and a few simple examples of its use on Tuesday. You can read chapter 11 in preparation.
Here are chapter 11 notes on the general equation for radiation transfer.

Examples and related literature

Comparison of 2 stream methods.

Week 8: 13 October

Continuing with topics covered in week 7.

Read chapter 7 on Atmospheric Transmission.
One topic for this chapter is cloud aerosol interaction - the relationship between
cloud albedo and cloud condensation nuclei number.

Chapter 7 Atmospheric Transmission (presentation).

Examples and related literature

Aerosol indirect effect -- Twomey effect. Twomey's 1974 paper.

Aerosols, clouds, and radiation (by Twomey, 1991).

Han et al, Global Survey of the Relationships of Cloud Albedo and Liquid Water Path with
Droplet Size Using ISCCP
.

Sengupta et al, Importance of Accurate Liquid Water Path for Estimation of Solar Radiation in Warm
Boundary Layer Clouds: An Observational Study
.

SBDART: A Research and Teaching Software Tool for Plane-Parallel
Radiative Transfer in the Earth's Atmosphere

SBDART for Matlab

Week 7: 6 October

Read chapter 7 on Atmospheric Transmission.
One topic for this chapter is cloud aerosol interaction - the relationship between
cloud albedo and cloud condensation nuclei number.

Chapter 7 Atmospheric Transmission (presentation).

Examples and related literature

Aerosol indirect effect -- Twomey effect. Twomey's 1974 paper.

Aerosols, clouds, and radiation (by Twomey, 1991).

Han et al, Global Survey of the Relationships of Cloud Albedo and Liquid Water Path with
Droplet Size Using ISCCP
.

Sengupta et al, Importance of Accurate Liquid Water Path for Estimation of Solar Radiation in Warm
Boundary Layer Clouds: An Observational Study
.

SBDART: A Research and Teaching Software Tool for Plane-Parallel
Radiative Transfer in the Earth's Atmosphere

SBDART for Matlab

Week 6: 29 September

Continue studying chapter 12 on scattering and absorption by particles (presentation).

Supplement to chapter 12, atmospheric column particle optics discussion useful for homework.

Simple explanation for the oscillations in Qext from interference of light through and around a particle.
Simple model for Qabs is also given. This model will be useful when we compute the particle emissivity.

Examples

See Saharan dust mixing with strong convection. Here's a backup image.

Week 5: 22 September

Read chapter 12 on scattering and absorption by particles (presentation).

Supplement to chapter 12, atmospheric column particle optics discussion.

Examples

Case study of the King fire, 16 September 2014.

Mie scattering calculator.

Week 4: 15 September

Read chapters 3, and 4 for the next few lectures.

Chapter 3 Electromagnetic spectrum (presentation).
Chapter 4 Reflection and Refraction (presentation).

Coming up.
Chapter 12 Scattering and Absorption by Particles (presentation).
Chapter 7 Atmospheric Transmission (presentation).
Chapter 13 Radiative Transfer with Multiple Scattering (presentation). (Read this classic paper on the subject).

Homework 3 has been posted. It summarizes chapters 1 through 4. Get started on it early; it's a challenge.

Examples:

Case study of the King fire, 16 September 2014.

Week 3: 8 September

Read chapters 2, 3, and 4 for the next few lectures. Bring any questions you have from the reading to class.
These chapters are highly related and we will discuss topics from each.

Chapter 2 Properties of electromagnetic radiation (presentation).

Coming up
Chapter 3 Electromagnetic spectrum (presentation).
Chapter 4 Reflection and Refraction (presentation).
Chapter 12 Scattering and Absorption by Particles (presentation).
Chapter 7 Atmospheric Transmission (presentation).
Chapter 13 Radiative Transfer with Multiple Scattering (presentation). (Read this classic paper on the subject).

Homework 3 has been posted. It summarizes chapters 1 through 4. Get started early on it; it's a challenge.

Examples:

Derivation and analysis of the Fresnel coefficients (website; local backup of the presentation).
Another discussion of these coefficients with more on the complex refractive index case (local backup).

Week 2: 2 September

Read chapters 2, 3, and 4 for the next few lectures.

Chapter 2 Properties of electromagnetic radiation (presentation).

Explore solutions of the wave equation for light; practical aspects of the refractive index.

Examples:

Electric field due to charge accelerated from rest to a constant velocity.


Week 1: 25 August

Introductions

Syllabus
Homework assignment
Presentation on chapter 1, Introduction, E&M waves, overview of radiation in the atmosphere and the global radiation balance.
Geostationary Satellite Images
examples of visible, IR, and water vapor.

Large scale analysis of a contemporary problem: Hiatus in global warming. (see this recent article).
Question we'll address: We have about 3 W/m2 longwave radiative forcing by greenhouse gases added to the atmosphere since the industrial revolution.
How long would it take the atmosphere to increase temperature by 1 degree C from 3 W/m2 being absorbed day and night?
How long would it take for the oceans to increase temperature by 1 degree C from 3 W/m2 being absorbed day and night?

Notes for this problem.


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