Global Observations of Stratospheric Heavy Ozone Isotopologue Enrichment with the Odin Sub-Millimetre Radiometer
Urban, Jo¹; Kasai, Yasuko²; Murtagh, Donal^1
1Chalmers University of Technology, Göteborg, SWEDEN; ²National Institute of Information and Communications Technology, Koganei, Tokyo, JAPAN

The study of ozone isotopologue fractionation is important for our understanding of the oxygen cycle in the Earth middle atmosphere. The Odin Sub-Millimetre Radiometer (SMR), launched in February 2001, measures thermal emission lines of several minor ozone isotopologues at the atmospheric limb. Observations of spectral lines of symmetric and asymmetric O3-18 are performed in a narrow spectral band centred at 490.4GHz. Limited information on asymmetric O3-17 is available from the same band. Measurements were performed on a regular basis of 4 observation days per month until April 2007 and about twice as often since then. The global Odin data set spans now a period of over 11 years.

Vertically resolved profiles can be retrieved in the stratosphere. We will describe the different data sets and their characteristics. The enrichment of the heavier ozone isotopologues compared to the main isotopologue was calculated and the global distribution of the enrichment will be presented. Best results in terms of spatial coverage are obtained for asymmetric O3-18, which shows a characteristic increase of the enrichment in the middle to upper stratosphere and the smallest enrichment in the polar regions. Other characteristics of the data, e.g. the observed temperature and pressure dependence of the heavy ozone enrichment or the time-evolution and seasonal variation of the observed ozone isotopologues during the Odin period are discussed.

Odin is a Swedish-led project funded jointly by Sweden (SNSB), Canada (CSA), Finland (TEKES), France (CNES) and the third party mission programme of the European Space Agency (ESA).