PC MODTRAN Tutorial
How to make an atmospheric model
in 47 easy steps.
Find MODTRAN and start it
• The PcModwin 4.0
icon should be on the
desktop, and you
double click on it to
get
Configure model input data
• Select Modtran
Input-> Model
Atmosphere (1)
Model atmosphere parameters
• Select model
Atmosphere->1976
U.S. Standard
• Select Type of
Atmospheric Path ->
Slant Path
• Select Mode of
Execution ->
Transmittance
Hit Next!
• Atmospheric Column
parameters – hit Next!
• Aerosols (note that
we’re using Rural,
with 23 km visibility)
– Hit Next
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!
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
Run the model
• Select Run Model->
Run Modtran
• Wait….
• Hit any key to
continue
Plot that puppy.
• Select Plot ->
Interactive
• Select MODOUT2
• Change X-axis to
Micrometers, hit okay
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.
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
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
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.
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.