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| Titel |
Stratospheric water vapour and temperature variability and their effect on polar stratospheric cloud formation and existence in the Arctic |
| VerfasserIn |
Farahnaz Khosrawi, Joachim Urban, Stefan Lossow, Gabriele Stiller, Katja Weigel, Peter Braesicke, Michael C. Pitts, Donal Murtagh |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102286
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| Publikation (Nr.) |
 EGU/EGU2015-1596.pdf |
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| Zusammenfassung |
| Based on more than 10-years of satellite measurements from UARS/HALOE, Envisat/MIPAS,
Odin/SMR, Aura/MLS and SciSat/ACE-FTS we investigate water vapour (H2O) variability
in the northern hemisphere polar regions. We find from the observations a connection
between cold winters and enhanced water vapour mixing ratios in the lower polar
stratosphere (475 to 525ÂK). We perform a sensitivity study along air parcel trajectories to
test how an increase of stratospheric water vapour of 1Âppmv or a temperature decrease of
1ÂK affects the time period during which polar stratospheric clouds (PSCs) can be formed
and exist. Air parcel trajectories were calculated 6-days backward in time. The trajectories
were started at the time and locations where PSCs were observed by CALIPSO (Cloud
Aerosol Lidar and Infrared Pathfinder satellite observations) during the Arctic winter
2010/2011. We test the sensitivity of PSCs formation and existence to changes in H2O and
temperature based on PSC observations during this winter since it was one of the coldest
Arctic winters in the last decade. The polar vortex persisted over a period of four
months, thus leading to extensive PSC formation. During this winter PSCs were
detected by CALIPSO on 42 days. In total, 738 trajectories were calculated and
analysed. The resulting statistic derived from the air parcel trajectories shows a
clear prolongation of the time period where PSCs can be formed and exist when
the temperature in the stratosphere is decreased by 1ÂK and H2O is increased by
1Âppmv. We derive an increase in time where the stratospheric air is exposed to
temperatures below Tice and TNAT, respectively, by ~6000Âh. Thus, changes in
stratospheric water vapour and temperature can prolong PSC formation and existence
and thus have a significant influence on the chemistry of the polar stratosphere. |
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