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was modeled according to LIDAR measurements if the cloud was penetrable. Otherwise,
the cloud model was not run. Cloud height was obtained from the LIDAR.
MODTRAN-P Limitations
The developers of the first release of MODTRAN-P have elected to remove
certain capabilities from the original MODTRAN input deck. Since MODTRAN-P is not
in full release, these limitations are not consistently documented, yet. The limitations
listed below have been found in a few papers and by word of mouth from people close to
the project.
Multiple scattering apparently is not properly implemented for polarization. All
multiple scattering is modeled as totally unpolarized (Fetrow, 2006). Therefore, inclusion
of proper multiple scattering—which is necessary to an accurate model—is impossible.
Using multiple scattering in the current code reduces the overall degree of polarization, as
it should, but it does so at a rate that is not realistic. The magnitude of this problem is
tested in the clear-sky models section.
Only a sub-set of the default aerosol models is available (PPS V4.3 Command
Line Usage, 2005). The Navy maritime model, the two fog models, and the desert model
are not implemented in the current version. For the simulations here, the Urban,
Tropospheric, and Rural models were used for the standard aerosol type.
Finally, this version of the code uses a standard scattering phase function that
does not allow the user to achieve realistic modeling for the aerosols present in a
particular measurement. Furthermore, it has been shown that improved phase functions