Infrared measurements of atmospheric CH_3CN

• Published in: Geophysical Research Letters
• Main Authors: Kleinböhl, Armin, Toon, Geoffrey C., Sen, Bhaswar, Blavier, Jean-François L., Weisenstein, Debra K., Wennberg, Paul O.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2005
• Subjects: Arctic
• Online Access: https://authors.library.caltech.edu/46620/; https://authors.library.caltech.edu/46620/1/grl20563.pdf; https://authors.library.caltech.edu/46620/7/grl20563-sup-0001-README.txt; https://authors.library.caltech.edu/46620/8/grl20563-sup-0002-text01.txt; https://authors.library.caltech.edu/46620/9/grl20563-sup-0003-ts01.txt; https://authors.library.caltech.edu/46620/10/grl20563-sup-0004-ts02.txt; https://authors.library.caltech.edu/46620/15/grl20563-sup-0005-fs01.eps; https://authors.library.caltech.edu/46620/16/grl20563-sup-0006-fs02.eps; https://authors.library.caltech.edu/46620/17/grl20563-sup-0007-text02.txt; https://authors.library.caltech.edu/46620/18/grl20563-sup-0008-ts03.txt; https://authors.library.caltech.edu/46620/19/grl20563-sup-0009-ts04.txt; https://authors.library.caltech.edu/46620/23/grl20563-sup-0010-text03.txt; https://authors.library.caltech.edu/46620/25/grl20563-sup-0011-text01.txt; https://authors.library.caltech.edu/46620/26/grl20563-sup-0012-ts01.txt; https://authors.library.caltech.edu/46620/27/grl20563-sup-0013-ts02.txt; https://authors.library.caltech.edu/46620/31/grl20563-sup-0014-fs01.eps; https://authors.library.caltech.edu/46620/32/grl20563-sup-0015-fs02.eps; https://authors.library.caltech.edu/46620/33/grl20563-sup-0016-text02.txt; https://authors.library.caltech.edu/46620/34/grl20563-sup-0017-ts03.txt; https://authors.library.caltech.edu/46620/37/grl20563-sup-0018-ts04.txt; https://authors.library.caltech.edu/46620/38/grl20563-sup-0019-text03.txt; https://resolver.caltech.edu/CaltechAUTHORS:20140702-090327628

For the first time CH_3CN has been measured in the Earth's atmosphere by means of infrared remote sensing. Vertical profiles of volume mixing ratio were retrieved from 12 solar occultation measurements by the balloon-borne JPL MkIV interferometer between 1993 and 2004. Profile retrieval is possible in an altitude range between 12 and 30 km with a precision of ∼20 ppt in the Arctic and ∼30 ppt at mid-latitudes. The retrieved CH_3CN profiles show mixing ratios of 100–150 ppt a few kilometers above the tropopause that decrease to values below 40 ppt at altitudes between 22 and 30 km. The CH_3CN mixing ratios show a reasonably compact correlation with the stratospheric tracers CH_3Cl and CH_4. The CH_3CN altitude profiles and tracer correlations are well reproduced by a 2-dimensional model, suggesting that CH_3CN is long-lived in the lower stratosphere and that previously-proposed ion-molecule reactions do not play a major role as loss processes of CH_3CN.