Atmospheric Carbon Dioxide Concentration at Jubany Station

CO2 concentration of the atmosphere at the Laboratory level are obtained at the station Jubany managed jointly by PNRA of Italy and DNA of Argentina. The measurements are taken by using a Siemens U5 analyzer based on NDIR (Non Dispersive InfraRed) absorption method. The air is sampled by using an intake placed at 10 m above the ground, then is pumped inside the Laboratory. Before entering the analyzer the water vapor of the air is subtracted by using a cold trap (< -70 degrees C).

The analyzer scale is periodically automatically calibrated (every 3 hours) by using station standards (tanks containing synthetic air having an assigned CO2 concentration). These tanks are re-determined every week comparing their concentration vs. a set of so-called secondary standard and finally secondary standards are calibrated (every 3-4 months) vs. a set of primary standards whose concentration was assigned by a WMO Reference Laboratory (now run by NOAA CMDL, Boulder). The Reference Laboratory maintains the so-called WMO scale determined by an absolute method and all the Institutions and Laboratories participating in the WMO-GAW (Global Atmospheric Watch) use the same scale.