Py4CAtS --- Python for Computational ATmospheric Spectroscopy

Main Scripts/Functions: From Hitran/Geisa to Cross Sections to Optical Depths

extract: extract (select) lines of a certain molecule (and isotope) and/or wavenumber range from line parameter database
lbl2xs: line-by-line (lbl) cross sections for some molecule(s) and some p, T
lbl2od: computation of line-by-line optical depth due to molecular absorption (combines lbl2xs, xs2ac, ac2od)

Installation: Getting started with Py4CAtS

Download a tarball of Python sources, some data files, and the documentation and unpack it at some convenient place:
tar xfvz py4cats-lite.tgz

The top-level directory py4cats-lite includes a 1.ReadMe file with basic instructions, and four subdirectories bin, data, doc, and src.

Prerequisites: Python (version 2.6 or 2.7) and numpy (scipy sometimes and matplotlib for plotting)

And you need some line data (HITRAN and/or GEISA). For the beginning, here is a thermal infrared excerpt of Hitran 86.

Usage

Py4CAtS can be used in two ways, from the Unix/Linux (or Windows/Mac?) console/terminal or (much better, more flexible, ..... See the demo !NEW!

or the poster for the ASA-HITRAN 2016 congress) inside the (I)Python interpreter.

Documentation

For a detailed review of line-by-line modeling for infrared radiative transfer see the manual py4cats-lite.pdf in the doc directory.
Sections 5 and 6 describe Py4CAtS' usage from the Unix/Linux shell and the (i)python shell, respectively.

How to cite Py4CAtS?

F. Schreier and S. Gimeno Garcia. Py4CAtS – Python Tools for Line-by-Line Modelling of Atmospheric Radiative Transfer. In Robert F. Cahalan and Jürgen Fischer (editors), Radiation Processes in the Atmosphere and Ocean (IRS 2012): Proceedings of the International Radiation Symposium (IRC/IAMAS) Volume 1531 of AIP Conference Proceedings, pages 123 - 126. American Institute of Physics, 2013. doi: 10.1063/1.4804723
See also GARLIC (Py4CAtS' big brother)

(download BiBTeX entries)

What's new?

July 2015: The 'main' scripts (e.g. lbl2od) can now be used as functions inside the (I)Python interpreter.
October 2015: Sources thoroughly checked with Pep8, PyFlakes, and PyChecker
Script od2ri with function dod2ri added to compute radiation intensity
March 2016: A new function cgs in module cgsUnits.py for easier conversions of physical quantities
Improved ac2wf.py and od2ri functions/modules.
July 2016: Further source code checks with Pylint; Absorption coefficients and optical depths are now stored in subclassed numpy arrays acArray and odArray (similar to xsArray before)
September 2016: Atmospheric data: corrected "CH3CL" -> "CH3Cl"; Functions atlas (in module lines.py), acPlot (in module absCo.py), and odPlot (in module oDepth.py) rewritten (to exploit recursive calls)
October 2016: xs2ac corrected to allow single level atmosphere and cross sections
November 2016: od2ri corrected to allow atmospheric data starting at ToA; Some further checks of 'important' function arguments implemented; srf.py: wavenumber shift implemented in fts function; Atmospheric data sets: trace gas profiles saved in separate file
December 2016: Setup script py4cats.py 'generalized' for Windows (pathname construction!); Line mixing added (first order, Voigt and Lorentz, "brute force" only); read_line_file in the lines.py script now works recursively; atlas now also allows to plot voigtLines; misc.py: new function triSpec for convolution with triangular; moreFun.py: new function erfcx for exponentially scaled complementary error function
May 2017: Function atmPlot now can plot volume mixing ratios (instead of densities), too.
radiance2radiance clean-up
November 2017: New subclassed numpy array for radiance/intensity (i.e. the radiance array along with its attributes): single return variable of function dod2ri.
New function riPlot and updated/adjusted function riSave to plot and save radiance.
New function truncate in module misc.py
January 2018: atmos1D.py:
New function readVMR to read (trace) gas concentration data (i.e. without pressure and temperature);
Function merge_atmos1D can use pure VMR data as second input.
Atmospheric data sets clean-up, reorganized, ...
March 2018: py4cats.py:
Identification / location of path to source files reorganized; wgtFct.py:
(Unix/Linux/...) shell interface adjusted to acArray implementation; lbl2xs.py (and extract.py, hitran.py, geisa.py):
Pressure-induced line shift implemented