CONCENTRATION VARIATIONS OF ATMOSPHERIC CO2 OVER SYOWA STATION, ANTARCTICA AND THEIR INTERPRETATION

Aircraft and ground-based measurements of the atmospheric CO2 concentr ation have been made at Syowa Station, Antarctica since January 1983. The minimum concentration of the average seasonal CO2 cycle occurs in March throughout the troposphere, while the maximum concentration appe ars in mid-August in the upper troposphere and in late September in th e lower and middle troposphere. The peak-to-peak amplitude of the cycl e decreases slightly with height. The CO2 concentration increases with height during most of the year, but from late winter to spring this h eight dependency is minimal. To examine the contribution of the atmosp heric transport processes to these variations of the CO2 concentration , a 3-dimensional trajectory analysis was performed using data from th e US National Meteorological Center; From the results obtained, it is postulated that northern hemispheric air with relatively high CO2 conc entration is transported to the antarctic region through the upper tro posphere from late fall to winter, while air with low CO2 concentratio n is transported from the southern hemisphere middle latitudes into th e antarctic region through the lower troposphere in the remaining seas ons. It is hypothesized that these air transport processes could influ ence CO2 variations over the station.