Observations of carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) mole fractions from the Los Angeles Megacity Carbon Project

Updated April 2025. Here we provide hourly observations of carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) mole fractions in dry
air from tower- and rooftop-based sites in the Los Angeles Megacity Carbon Project network. Each *.tgz (tar/gzip) archive contains data files
for a given site location, named by its 3-letter code. To extract *.tgz files on a unix platform, use "tar -xvzf <filename>". Data files with
in the <site>-1-hr-CSV.tgz archives are comma delimited (CSV) 1-hour averages; data files within the <site>_1-hr-NC.tgz archives are 1-hour
averages in NetCDF format; data files within the <site>-1-min-CSV.tgz are CSV files with 1-minute averages (there is no NetCDF version for
1-minute data). Site locations, heights, and other information are in a separate ascii (CSV) file (LAM_sites.csv), and also within each data file
(for the 1-hour averages files). We encourage the use of the locations within the hourly data files, as some locations may have changed during
the site lifetime and have duplicate entries in the site file. Data in this archive is for January 1 2015-January 31 2025. ASCII Readme files
(1Readme_v20250425.txt and 1Readme_1minfiles_v20250425.txt) contain data details; Updates_v20250425.pdf includes additional information on
updates since the previous data version. Note about calibrations: CO2 data are reported on the NOAA/WMO X2019 calibration scale. CH4 data are
reported on the NOAA/WMO X2004A calibration scale; CO data, where available, are reported on the NOAA/WMO X2014 scale. Note that previous archive
s of this data reported CO2 on the X2007 scale. This data is being freely distributed for research, academic and related non-commercial
purposes consistent with NIST's mandate to further the science and the promulgation of appropriate standards. Current update: April 25, 2025.