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UP: Umweltphysik

UP 11: Poster: Atmosphärenphysik und Physikalische Altersbestimmung

UP 11.29: Poster

Freitag, 19. März 1999, 12:45–14:30, KO

Measurements of the large scale distribution of Acetone in the upper troposphere in the North Atlantic region: Implications for HO₂ formation — •K.-H. Wohlfrom, T. Hauler, and F. Arnold — MPI for nuclear physics, atmospheric physics division, P.O. Box 103980, D-69029 Heidelberg

Acetone is an important atmospheric trace gas which is released to the atmosphere by direct emissions as well as by oxidation of atmospheric organic precursors, e. g. higher alkanes and alkenes. It is removed either by reaction with OH radicals or by photolysis. The latter process which is the more important in the upper troposphere results in the production of HO₂ radicals and may provide an important source of HO₂. Furthermore the decomposition of acetone leads to the formation of peroxyaxcetylnitrate (PAN), an important reservoir gas for nitrogen oxides. Acetone was originally detected in the free troposphere by our group using aircraft-based Ion Molecule Reaction Mass Spectrometry (IMRMS). Here we report on extended measurements of acetone which have been carried out within the POLINAT-2 campaign in the North Atlantic region between 28^oN and 61^oN in fall 1997. A cooporation with the SONEX project carried out by NASA and using the NASA DC-8 aircraft as measurement platform offered the opportunity to intercompare the IMRMS technique with another acetone measurement technique using cryocenic sampling of acetone with gas chromatic detection. Within their accuracy both measurements showed good agreement. Measured acetone volume mixing ratios in the upper troposphere range between 0.5 and 2 ppbV showing the considerably large abundance of acetone in the upper troposphere.