Py4CAtS --- Python scripts for Computational ATmospheric Spectroscopy

Molecular Spectroscopic Databases

HITRAN molecular database
GEISA data bank
JPL - Submillimeter, Millimeter, and Microwave Spectral Line Catalog

In order to compute line-by-line cross sections and optical depths, you first have to extract the relevant spectroscopc line parameters from the HITRAN or GEISA databases. See the data/lines subdirectory for typical line parameter files (listing the "essential" parameters only, i.e., line positions v, Strengths, lower state Energy, air broadening widths and its temperature dependency exponent n). According to the default naming convention, the filename head indicates the molecule, and the extension indicates the data columns.

Atmospheric Data

The file containing an user's atmospheric profile data has to be in xy format:
(netcdf will come soon (hopefully))

comment lines in this file have to begin with # in the first column
(Actually 'any' character can be used, i.e. using the -c option the default # can be changed)
a comment line starting with #where: can be used to include some info for the job
at least 2 comment lines are mandatory:
#what: followed by identifiers, e.g. altitude, molecular names, pressure, or temperature
#units: followed by the physical units, e.g. km, mb, K, ppm
If the very first column is altitude, some abbreviated forms are recognized, too:, e.g.
# altitude pressure temperature
or
# z p T
and
# km mb K
a column for altitudes is mandatory (marked ALTITUDE or HEIGHT in the #what: record)
columns with profiles not requested by the user (e.g. IR inactive gases) are ignored
the number of columns in the data section and the number of identifiers and units given above have to be identical

Example:

#comment this line will be ignored
#info:   this is ignored, too
#note:   the next line is optional
#where:  bavarian foehn
#what:   Height  Temperature  CO2   H2O   NO
#units:  km      K      cm-3            cm-3            cm-3
        0.0	300	7.671e+15	1.875e+17	1.53e+13
        0.2	298	8.641e+15	2.557e+17	1.72e+11
        0.4	296	7.929e+15	2.544e+17	4.24e+10
        0.6	293	7.417e+15	2.620e+17	1.73e+10
        0.8	290	7.280e+15	2.711e+17	9.05e+09
        1.0	285	7.179e+15	2.771e+17	6.03e+09
        2.0	280	6.915e+15	1.875e+17	5.81e+09
        3.0	275	6.333e+15	1.061e+17	5.32e+09
        4.0	270	5.802e+15	6.197e+16	4.87e+09
        5.0	260	5.308e+15	3.308e+16	4.46e+09

Further Data Sources

NIST
Physical Reference Data
Fundamental Physical Constants
Molecular Spectroscopic Data (Wavenumbers for IR, microwave, and millimeter regions)