Read me file for Ray et al., 2024

All of the programs for this work were written in idl.  There is an 'IDL_Code' folder that contains all of the programs and a 'Data' folder that contains all of the data with a subdirectory structure that matches that in the programs.

The merged aircraft and balloon data files are in idlsave format and the original data files can be obtained from the NASA archive (https://espoarchive.nasa.gov/archive/browse) or for the newer missions such as DCOTSS from 
https://www-air.larc.nasa.gov/missions/dcotss/, SABRE from https://csl.noaa.gov/projects/sabre/data.html and AirCore from https://gml.noaa.gov/ccgg/arc/?id=144.

We have also included netcdf versions of the mean ages and several other variables for aircraft and balloon data for both the ‘early’ and ‘late’ periods.  These are found in the ‘Data/Aircraft/’ and ‘Data/Balloon/’ directories.

The surface data is primarily from the NOAA Greenhouse Gas Marine Boundary Layer Reference (https://gml.noaa.gov/ccgg/mbl/).

Code overview

1. Run the four make_tropical* files first.

2. Run create_entry_time_series.pro 

3. Run mean_ages_aircraft.pro for both 'early' and 'late' missions.  The first eight missions in the 'mission_names' variable constitute the 'early' missions and the last three missions constitute the 'late' missions.  The 'early' and 'late' time periods are referred to as the 1990s and 2020s respectively in the paper.
   
4. Run test_age_spectra_sweeps.pro for 'early' and 'late' missions.