To elucidate temporal variations of greenhouse gases and their related gases in the Arctic and Antarctic regions and to investigate their sources and sinks, systematic measurements of atmospheric CO 2, CH 4, CO, N 2O, O 2 and tropospheric O 3 concentrations have been carried out at Syowa Station, Antarctica and Ny-Alesund, Svalbard. The CO 2 concentrations at both polar sites have increased at a rate of about 1.9 ppmv yr -1, reflecting fossil fuel combustion and land use change. The CH 4 concentrations also showed clear seasonal cycles superimposed on complex secular trends. The increase rate of the CH 4 concentration varied with time. CH 4 increases were observed until 1999, the concentrations remained steady from 2000 to 2006 and then rapid increases were observed in 2007. Stable isotope data of CH 4 revealed causes of the seasonal cycles and the secular variations of the CH 4 concentrations. The O 2 concentrations (δ(O 2/N 2)) at both polar sites showed prominent seasonal cycles and secular decreasing trends. From analyses of the Atmospheric Potential Oxygen (APO) and CO 2 concentrations, the CO 2 uptake rates by the terrestrial biosphere and the ocean were estimated to be 1.1 and 2.7 GtC yr -1, respectively. By comparing the N 2O concentrations observed at Ny-Ålesund and numerical model results, it was suggested that the observed seasonal N 2O cycle could be enlarged by intrusion of a stratospheric air mass with low N 2O concentration into the troposphere in summer. With an analysis using a three dimensional chemical-transport model and the CO concentration at Syowa Station, sporadic increases of CO concentration observed in February-March, 2003 and February, 2007 were ascribed to CO release by large-scale forest fires in Australia. Surface ozone depletion events were observed more than 40 times at Syowa Station from 1988 to 2007.
|Number of pages||36|
|Issue number||SPEC. ISSUE|
|Publication status||Published - 2010 Dec|