1. How to make an atmospheric model in 47 easy steps.
PC MODTRAN Tutorial
How to make an atmospheric model in 47 easy steps.

2. Find MODTRAN and start it
The PcModwin 4.0 icon should be on the desktop, and you double click on it to get

3. Configure model input data
Select Modtran Input-> Model Atmosphere (1)

4. Model atmosphere parameters
Select model Atmosphere->1976 U.S. Standard
Select Type of Atmospheric Path -> Slant Path
Select Mode of Execution -> Transmittance

5. Hit Next! Atmospheric Column parameters – hit Next!
Aerosols (note that we’re using Rural, with 23 km visibility) – Hit Next

6. Geometry and Spectral Band (3) lots to do here
Many path types, use default
Observer height – 60 km
Final Height – 0 km
Zenith Angle – 180 degrees
Initial Frequency 0.5 microns
Final Freq 2.9 microns
Next!

7. Sanity check diagram
The model parameters are reproduced here to make sure that the program is configured correctly.
Model parameters at top
Note diagram showing viewing geometry

8. Run the model Select Run Model-> Run Modtran Wait….
Hit any key to continue

9. Plot that puppy. Select Plot -> Interactive Select MODOUT2
Change X-axis to Micrometers, hit okay

10. Wait for it to plot twice
Now we have a plot of transmissivity in the VNIR, and you can answer the questions in lab. Oh wait, perhaps a little more direction would be helpful.
First trick. Clicking on the plot will show the X and Y location you’ve clicked on the upper left corner. This is probably all you need to answer the first question.

11. More Plotting Tricks
If you’re one of those types who has to have the exact answer, you can adjust the plotting parameters as you like.
Select Plot->Edit Plot
For example: Autoscale: OFF Min X=1, Max X=1.1 X Decimal = 2 (you might have to fiddle with X Divisions too) will yield

12. A Beautiful Butterfly of a Plot
So that you can get ridiculously exact about answering the questions in the lab.
For example: Autoscale: OFF Min X=0.938, Max X=0.946 X Decimal = 5 will yield the plot on the next page

13. Still more plotting tricks
There are also ways to plot one data set over another, and various other things that you should mess around with, but first answer the first question in the lab. Then go to the next page to do the tropical model, and answer those questions.

14. Tropical Model Click on Card1 Input
Which brings up the dialog box Model Atmosphere(1)
Select Model Atmosphere-> Tropical Model
Hit okay, and run the model again. Plot it and fill in the blanks on the answer sheet for Tropical model.