Ground based in situ observations of carbon_monoxide at Zeppelin mountain (Ny-Ålesund) (NO0042G) using GC-HgO. These measurements are gathered as a part of the following projects CAMP, AMAP, NILU, EMEP and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: carbon_monoxide in air (mass_fraction_of_carbon_monoxide_in_air)