TROPOSPHERIC HYDROGEN AND CARBON OXIDES IN ANTARCTICA AND IN GREENLAND

Tropospheric trace gases (H-2, CO, and CO2) were measured in polar areas for two seasons in Antarctica (Italian base Terra Nova Bay) and two in Greenland (European base Summit, Greenland Icecore Program [GRIP]), yielding the following average concentrations: Antarctica (1989-1990): H-2, 528 ppbv; CO, 51 ppbv; CO2, 354 ppmv; Antarctica (1990-1991): H-2, 522; CO, 51; Greenland (1991): H-2, 548; CO, 114; Greenland (1999): CO, 107 (hydrogen discarded). Computer automated gas chromatographic analyses were done in situ using a reduction gas detector (RGD) and a complete set of standards each day, for periods of 2 h in Greenland and 3 h in Antarctica. Approximately 200 analyses were conducted during each campaign. Peak areas and standard calibrations in the laboratory were obtained using programs written especially for the purpose. For both Antarctica and Greenland, some differences were found between the two subsequent seasons; the greatest differences, however, were found in Antarctica within the same season (different origins of air masses). The inter-hemispheric asymmetry is clear and significant. It most likely occurs because pollution from the northern hemisphere reaches the northernmost regions through the polar vortex, whereas Antarctica is more isolated by the Southern Ocean.