The measurement programme of the CH4 has been run by CESI RICERCA since February 1991 (at beginning by means of biweekly samplings until December 2002 and then by means of continuous measurements since January 2002). The measurements have been stopped from May 2006 to October 2007. Since 2008 the minimum temporal resolution for the mean values is based on hourly averages. Instrument: GC-FID, NIRA Venus 301 Duration of the analyses' cycle: 120 s. Detection limit: 20 ppb. The calibration measurements are realized by means of two working gas standard referred to primary standard. The working standard are systematically measured every six hours. CMDL X83 up to 2007. Since 2008 NOAA04 Scale. Convertion factor is: 1.0124. So, CMDL X83 * 1.0124 = NOAA04. In 2009, all CMDL X83 scale data have been expressed in NOAA04 scale. FLAG: "1" means "valid data". The data is considered correct but no criteria, at the moment, has been applied to identify the background data; "2" means "invalid data" (for example, instrumental problems due to the missed electrical power, incorrect calibration measurements, sampling flow incorrect and so on)

The monitoring station of Plateau Rosa is situated in the Western Italian Alps (3480m asl). It belongs to the National Institute for Astrophysics (INAF)-Institute of Interplanetary Space Physics (IFSI), Turin Section. The measurement programme of the CO2 has been run by CESI RICERCA since April 1989 (at beginning by means of biweekly samplings until December 1997 and then by means of continuous measurements since April 1993). The atmospheric CO2 concentration is measured by means of a non-dispersive infrared analyser (ULTRAMAT 5E and, in these last years, ULTRAMAT 6E). The CO2 measurements are referred to the WMO X2007 international mole fraction scale. The CO2 atmospheric concentration is expressed in ppmv in dry air. The measurement programme of the CH4 has been run by CESI RICERCA since February 1991 (at beginning by means of biweekly samplings until December 2002 and then by means of continuous measurements since January 2002). The CH4 atmospheric concentration is expressed in ppbv and the measured method is gas chromatography by using a FID (NIRA Mod. Venus). The surface ozone measurements (O3) is available since 1989 but only in these last years have been included in a specific internal protocol and submitted to WDCGG. The ozone atmospheric concentration is expressed in ppbv and the measured method is the UV light absorption analysis by using a Environnement 41M, and recently, a Thermo 49