**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 literatureHere'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 literatureVariability 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 isR, andR + T= 1.T=_{total}T / (1 - R * A. Click on the image for a larger_{g})

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 literatureComparison 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

**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 literatureAerosol 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.

**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 literatureAerosol 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.

**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 Q

_{ext}from interference of light through and around a particle.

Simple model for Q_{abs}is also given. This model will be useful when we compute the particle emissivity.

ExamplesSee 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.

ExamplesCase study of the King fire, 16 September 2014.

**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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