Five-year analysis of background carbon dioxide and ozone variations during summer seasons at the Mario Zucchelli station (Antarctica)

The work focuses on the analysis of CO(2) and O(3) surface variations observed during five summer experimental campaigns carried out at the 'Icaro Camp' clean air facility (74.7 degrees S, 164.1 degrees E, 41 m a.s.l.) of the 'Mario Zucchelli' Italian coastal research station. This experimental activity allowed the definition of summer average background O(3) values that ranged from 18.3 +/- 4.7 ppbv (summer 2005-2006) to 21.3 +/- 4.0 ppbv (summer 2003-2004). Background CO(2) concentrations showed an average growth rate of 2.10 ppmv yr(-1), with the highest CO(2) increase between the summer campaigns 2002-2003 and 2001-2002 (+2.85 ppmv yr(-1)), probably reflecting the influence of the 2002/2003 ENSO event. A comparison with other Antarctic coastal sites suggested that the summer background CO(2) and O(3) at MZS-IC are well representative of the average conditions of the Ross Sea coastal regions. As shown by the analysis of local wind direction and by 3-D back-trajectory calculations, the highest CO(2) and O(3) values were recorded in correspondence to air masses flowing from the interior of the Antarctic continent. These results suggest that air mass transport from the interior of the continent exerts an important influence on air mass composition in Antarctic coastal areas.