NOAA Global Monitoring Laboratory (GML) / Carbon Cycle Greenhouse Gases (CCGG)
Surface-flask CO2 sampling network -- text export

Mirror snapshot fetched 2026-05 from:
  https://gml.noaa.gov/aftp/data/trace_gases/co2/flask/surface/txt/

Citation
--------
Lan, X., Tans, P., Thoning, K., and NOAA Global Monitoring Laboratory.
"Trends in Globally-Averaged CO2 Determined from NOAA GML Carbon Cycle
Cooperative Global Air Sampling Network."  Updated annually; consult the
upstream URL above for the current dataset version.

Files in this directory
-----------------------
Naming pattern:  co2_<station>_surface-flask_1_ccgg_<event|month>.txt

  <station>   3-letter station code:
                mlo = Mauna Loa             brw = Barrow
                spo = South Pole            smo = American Samoa
                alt = Alert                 cgo = Cape Grim
                mhd = Mace Head             lef = Park Falls WLEF
                psa = Palmer Station        thd = Trinidad Head
  event.txt   per-flask measurements -- one row per individual flask
  month.txt   monthly arithmetic mean of the event-level data

Columns (event)
---------------
site, year, month, day, hour, minute, second, datetime, time_decimal,
midpoint_time, value, value_unc, latitude, longitude, altitude,
elevation, intake_height, qcflag, instrument, ...

Units: value in micromol mol-1 (ppm), dry air mole fraction.

Quality flags
-------------
qcflag is a 3-character code:
  ...  retained measurement
  .x.  retained but suspect -- rejected from baseline curve fits
  X..  rejected -- do not use

Re-use
------
This is a third-party static snapshot.  For ongoing research, pull
directly from the upstream GML server -- they update monthly and the
mirror here is not refreshed on a fixed schedule.