Download (V) lidort - Planetary Aeronomy

2.
General Description of the software
2.1 Implementation
The ASIMUT program has been written in the C programming language. The
modularity of the program has been one of the driving motives to write our own code.
Most options driven by the user’s choices may be easily extended. It is for example
relatively easy to add a new instrument: the only additional information that the user
must provide are a function to read the spectra and the instrument line shape function.
Another example is the possibility to add other absorption line shapes, besides the
ones already implemented.
As one of the objectives was to be able to run the program either on Windows based
PCs or on Unix systems, graphical output possibilities are not implemented in the
code. However, graphics are possible through the opening of a Matlab session. Data
and graphics commands are automatically sent to Matlab while the ASIMUT program
is running, if the program has detected the presence of the Matlab environment on the
machine.
The user controls the program through a series of text files in which he can specify
what has to be calculated, saved and plotted (radiance, transmittance, Jacobians,
retrieval results), which spectra are analysed, in which order. It moreover describes
the observation geometry corresponding to each spectrum, the spectral intervals, the
molecules, cross sections and continua to be taken into account, and all parameters
needed for the treatment of the species (isotopes, list of line parameters, file for cross
sections, covariance matrices, aerosol characteristics).
The ASIMUT-(V)LIDORT (ALVL) software is a combination of 5 scientific
programs and 2 auxiliary blocks written in C and Fortran (see Figure 1 and Table 1).
ASIMUT interacts with the (V)LIDORT codes with the help of a special interface
used to transfer variables from C to Fortran and vice versa. The aerosol processing
SPHER and T-MATRIX codes are linked to the ASIMUT code directly. Input files
required for LIDORT/VLIDORT and changes in the ASIMUT input related to the
incorporation of the new RT are explained in detail in ASIMUT_Input_File.pdf.
Figure 1: Scientific programs included in the ALVL software package
7