Improvements in the carbon dioxide and methane continuous measurement programs at Izaña Global GAW Station (Spain) during 2007-2009

Abstract

Continuous in-situ measurements of atmospheric CO2 and CH4 have been carried out at Izaña Global GAW station (Tenerife, Spain) since 1984. In the present report, we briefly summarize some improvements done in those programs during 2007-2009. Firstly, we deal with the CO2 program. In January 2007, we installed a new NDIR analyzer (Li-7000), which became our main CO2 analyzer. The instrumental system is briefly described, additionally to the acquisition/control software and raw data processing numerical code, which have been developed by us. Some details are provided about the processes used to transfer the WMO scale to the atmospheric CO2 measurements, together with the instrumental response function used, its determination and uncertainty. We perform an uncertainty propagation analysis, obtaining a standard uncertainty of 0.035 ppm for the consistency of our atmospheric CO2 measurements with the WMO-X2005 CO2 scale. Secondly, the CH4 program is considered. The new numerical codes developed by us to integrate peak area and to process calibrations are very briefly described. Finally, our intercomparison activities are mentioned.