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| Titel |
In-situ observations of aerosol particles remaining from evaporated cirrus crystals: Comparing clean and polluted air masses |
| VerfasserIn |
M. Seifert, J. Ström, R. Krejci, A. Minikin, A. Petzold, J.-F. Gayet, U. Schumann, J. Ovarlez |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 3, no. 4 ; Nr. 3, no. 4 (2003-07-16), S.1037-1049 |
| Datensatznummer |
250001137
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| Publikation (Nr.) |
 copernicus.org/acp-3-1037-2003.pdf |
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| Zusammenfassung |
| In-situ observations of aerosol particles contained in cirrus crystals are presented and
compared to interstitial aerosol size distributions (non-activated particles in between the
cirrus crystals). The observations were conducted in cirrus clouds in the Southern and Northern
Hemisphere mid-latitudes during the INCA project. The first campaign in March and April
2000 was performed from Punta Arenas, Chile (54°S) in pristine air. The second campaign in
September and October 2000 was performed from Prestwick, Scotland (53°N) in the vicinity
of the North Atlantic flight corridor. Size distribution measurements of crystal residuals
(particles remaining after evaporation of the crystals) show that small aerosol particles
(Dp< 0.1 mm) dominate the number density of residuals. The crystal residual size distributions
were significantly different in the two campaigns. On average the residual size distributions
were shifted towards larger sizes in the Southern Hemisphere. For a given integral residual
number density, the calculated particle volume was on average three times larger in the
Southern Hemisphere. This may be of significance to the vertical redistribution of aerosol
mass by clouds in the tropopause region. In both campaigns the mean residual size increased
slightly with increasing crystal number density. The form of the residual size distribution did
not depend on temperature as one might have expected considering different modes of
nucleation. The observations of ambient aerosol particles were consistent with the expected
higher pollution level in the Northern Hemisphere. The fraction of residual particles only
contributes to approximately a percent or less of the total number of particles, which is the
sum of the residual and interstitial particles. Excellent agreement between the CVI and
FSSP-300 probes was found supporting the assumption that each crystal is associated with only one
residual particle. |
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