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| Titel |
Letter to the Editor: A strange cloud in the Arctic summer stratosphere 1998 above Esrange (68°N), Sweden |
| VerfasserIn |
J. Siebert, C. Timmis, G. Vaughan, K. H. Fricke |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 18, no. 4 ; Nr. 18, no. 4, S.505-509 |
| Datensatznummer |
250013961
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| Publikation (Nr.) |
 copernicus.org/angeo-18-505-2000.pdf |
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| Zusammenfassung |
When the University of Bonn lidar on the
Esrange (68°N, 21°E), Sweden, was switched on in the evening of July 18, 1998,
a geometrically and optically thin cloud layer was present near 14 km altitude
or 400 K potential temperature, where it persisted for two hours. The tropopause
altitude was 4 km below the cloud altitude. The cloud particles depolarized the
lidar returns, thus must they have been aspherical and hence solid. Atmospheric
temperatures near 230 K were approximately 40 K too high to support ice
particles at stratospheric water vapour pressures of a few ppmv. The isentropic
back trajectory on 400 K showed the air parcels to have stayed clear of active
major rocket launch sites. The air parcels at 400 K had traveled from the
Aleutians across Canada and the Atlantic Ocean arriving above central Europe and
then turned northward to pass over above the lidar station. Parcels at levels at
±25 K from 400 K had come from the pole and joined the 400 K trajectory path
above eastern Canada. Apparently the cloud existed in a filament of air with an
origin different from those filaments both above and below. Possibly the 400 K
level air parcels had carried soot particles from forest wild fires in northern
Canada or volcanic ash from the eruption of the Korovin Volcano in the Aleutian
Islands.
Key words: Atmospheric composition and structure
(aerosols and particles; biosphere-atmosphere interactions) · Meteorology and
atmospheric dynamics (middle atmospheric dynamics) |
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