PcModWin© is the world standard Windows interface for MODTRAN® (*). The latest version, PcModWin 6, works with MODTRAN6®.
PcModWin is a commercial Windows version of the United States Air Force Research Laboratory's MODTRAN model. MODTRAN is the recognized standard for computing atmospheric transmission and radiance at medium to high spectral resolution (0.1 cm-1). PcModWin wraps around MODTRAN and makes it easy to use.
PcModWin is a user-friendly input/output generation system developed by Ontar. It is a Windows-based program that organizes the inputs into screens that are easy to fill out. Instead of selecting integers for cryptically named variables and hand-editing a formatted text file, you can point and click selections to prompts like "Model Atmosphere". PcModWin creates the necessary formatted input files to run MODTRAN6®, based on your inputs. It also includes output plotting to quickly view the results of a calculation.
A user just clicks on the inputs and selects the appropriate values from easy to understand prompts. More detail on any input can be viewed by clicking on the input label, which calls up a large Windows help file with a complete description of the prompt. Compare this with a typical ASCII input file required to run MODTRAN directly:
T 6 1 0 0 0 0 0 0 0 0 0 0 0 0.000 0.00
F 2T 5 330.000
1 0 0 0 0 0 0.000 0.000 0.000 0.000 0.000
6.000 10.000 30.000 0.000 0.000 0.000 0 0.000
2050.000 2150.000 1.000 1.000
If you compile MODTRAN yourself and run it from a command line, you must hand edit text files like this and make sure numbers are lined up in the proper columns to satisfy the requirements of formatted FORTRAN input. Part of the very first line of this file corresponds to the inputs shown on the window above. It gets worse because as some inputs are set to certain values, new MODTRAN options are enabled, so new lines of inputs are required (in the correct order, of course). MODTRAN input files using complex options like user defined atmospheres can easily run to 100 lines or more in length. PcModWin will generate all of these files with proper formatting automatically for you. For most people, filling out an input window like the one above is easier than editing a text file like this!
The most significant new feature in MODTRAN® 6 and hence PcModWin is the capability to do line-by-line (LBL) transmission and radiance calculations. This means MODTRAN® calculations are applicable for laser calculations at all pressures at a spectral resolution determined by the HITRAN database. This is a significant enhancement over MODTRAN 5 with the 0.1 to 0.2 cm-1 capability. Hence there is no longer the need to us FASCOD for LBL calculations. Please see test case 1.5.11 AnLBLTemplate below for instructions on LBL calculations
The other changes from previous versions of MODTRAN are the input file format, and the programming language used for the source code. Previously, the code was written in FORTRAN with formatted FORTRAN input/output files. The current version is a combination of C++ and FORTRAN source code. The input can be in either the older FORTRAN format, i.e. tape5 etc., or in JSON format.
The material here is taken from MODTRAN® 6.0.0 User's Manual (revision 5), performed under US Government Contract No. FA9453-12-C0262; Data Item A007, July 2016. A. Berk, J. van den Bosch, F. Hawes, T. Perkins, P.F. Conforti, G.P. Anderson, R.G. Kennett, and P.K. Acharya.
A summary of new features includes:
This file was added to the set of test cases to serve as a template for doing line-by-line (LBL) calculations. We recommend you start with this case and modify it to meet your specific requirements.
It is for a slant path geometry, using a Mid-Latitude atmospheric model. It calculates radiance with scattering over the 0.7 to 1.2 μm spectral interval (i.e. visible to near IR). It includes multiple scattering using the Isaac 2 stream algorithm. Because of scattering and spectral interval, this calculation may take several hours to complete.
For most applications, you will do calculations over a much smaller spectral interval which will significantly reduce the time. However, keep the following "rules of thumb" in mind:
Consequently, we recommend:
An LBL calculation requires three major changes to a "standard", e.g. MODTRAN® 5 file as shown in the figures below.
Also, keep in mind that an LBL calculation may generate large files depending on the options selected. For example, the *_highres.csv file may have over 1,000,000 lines if you cover a 1000 cm-1 spectral region.
Three are three parameters that must be set to do an LBL calculations. They are:
3. Select the LBL2013 Band Model on the second input screen as shown in the next figure. The band mode file determines the spectral resolution of the MODTRAN® calculation. For example: 01_2013.bin is for 1 cm-1 resolution; 05_2013.bin for 5 cm-1; and p1_2013.bin for 0.1 cm-1.
The next set of figures are plots of the AnLBLTemplate.ltn calculation. Please NOTE, the plots in the first two figure are at 0.1 cm-1 spectral resolutions. These correspond to the data in *.tp6, *.tp7, MODOUT 1, MODOUT2 and *.csv files. The high resolutions data is given in *_highres.csv. These files can be found in the PcModWin/bin and PcModWin/usr/output directories.
Other enhancements made to Ontar's PcModWin user interface recently include:
* The MODTRAN5® trademark is being used with the express permission of the owner, the United States of America, as represented by the United States Air Force.