The files in this directory are am model configuration files based on
zonally and seasonally averaged vertical profiles.  These profiles are
averages derived from the NASA MERRA-2 reanalysis for the decade
2006 - 2016.  For more background information and references, see the
comments in the .amc files.

In each directory here, the file names are of the form

    zone_season.amc
    zone_season.png
    zone_season.txt

where 'zone' indicates the latitude range, and is one of

    Arctic                66 N to 90 N
    northern_midlatitude  23 N to 66 N
    tropical              23 S to 23 N
    southern_midlatitude  66 S to 23 N
    Antarctic             90 S to 66 S

and 'season' is one of

    annual  mean over entire year
    DJF     December, January, February
    MAM     March, April, May
    JJA     June, July, August
    SON     September, October, November

The .amc files are basic am configuration files based on the profiles
tabulated in the .txt files.  The .png files are plots for convenient
viewing of the profiles.

Note that the models in the .amc files start from sea level.  Users
interested in modelling zonally-averaged atmospheric properties from
higher surface altitudes, aircraft, or balloons can simply comment out
or delete layers at lower altitude, and interpolate the lowest layer
if needed.