Generating GGG2020 atmospheric profiles

The GGG pipeline is used by the Total Carbon Column Observing Network (TCCON) to process their spectra and compute the total column abundances of the relevant gases. The current version of the pipeline is GGG2020 and one of its applications is an algorithm that allows the user to compute a priori profiles for several gases. This algorithm is called ginput and is publicly available on GitHub.

Installing ginput

To install and learn how to use ginput, see their documentation. Astroclimes comes with its own installation of ginput found in the directory py-ginput/, along with other necessary files inside the tccon/ directory. This installation should work by simply copying it to your local repository, you just need to change the shebang pointing to the Python executable in the right conda environment and the default GGG2020 path on your .bashrc file.

Downloading the necessary auxiliary files

ginput relies on meteorological data to compute atmospheric profiles. These come from the Goddard Earth Observing System Forward Product (GEOS FP), provided by the Global Modelling and Assimilation Office (GMAO) at NASA Goddard Space Flight Center through the online data portal in the NASA Center for Climate Simulation (NCCS). The auxiliary files required are the 3D meteorological (inst3_3d_asm_Nv), 3D chemical (inst3_3d_chm_Nv) and 2D surface (inst3_2d_asm_Nx) information files. You can either download them manually from the online data portal, or download them automatically with the help of the get_GEOS_aux_files.py script which can be found in the py-ginput/ directory. To do so, simply change the path assigned to the home_directory variable and the path to the data on the spec_file_list variable and run:

>>> python get_GEOS_aux_files.py

This script will create, if not already existent, the directory GEOSFP/ inside Astroclimes/data/ and the subdirectories GEOSFP/Nv/ and GEOSFP/Nx/, where the auxiliary files will be stored. At this stage, the spectroscopic data is only used to get the observations dates. You may wish to run this script before obtaining the observational data, as long as you specify the dates in a different way.

Running ginput

Once you have the GEOS-FP auxiliary files, the GGG2020 atmospheric profiles can be generated with the help of the generate_GGG20202_atm_profs.py script, also in the py-ginput/ directory. Again, simply change the path assigned to the home_directory variable and run:

>>> python generate_GGG20202_atm_profs.py

Note

This script will generate the .mod, .vmr and map files (the latter in .txt format) and store them in their appropriate subdirectories inside Astroclimes/atmosphere_profiles/GGG2020/fp/al/. For some reason, the subdirectory for the map files is not automatically created, so you must make sure the directory Astroclimes/atmosphere_profiles/GGG2020/fp/al/maps-vertical/ already exists.

The generate_GGG20202_atm_profs.py script is by default tailored to Calar Alto. If you wish to calculate atmospheric profiles for a different site, you must change the site variable, provided the site is among the TCCON site list (if it is not, you can simply add a custom site to the tccon_sites.py file found in Astroclimes/py-ginput/mod_maker/), or alternatively change the options on the lines calling the run_ginput.py script from --site to --lat and --lon and specify the coordinates.