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| Titel |
Airborne measurements of the nitric acid partitioning in persistent contrails |
| VerfasserIn |
D. Schäuble, C. Voigt, B. Kärcher, P. Stock, H. Schlager, M. Krämer, C. Schiller, R. Bauer, N. Spelten, M. Reus, M. Szakáll, S. Borrmann, U. Weers, Th. Peter |
| 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 ; 9, no. 21 ; Nr. 9, no. 21 (2009-11-02), S.8189-8197 |
| Datensatznummer |
250007719
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| Publikation (Nr.) |
 copernicus.org/acp-9-8189-2009.pdf |
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| Zusammenfassung |
| This study reports the first systematic measurements of nitric acid (HNO3)
uptake in contrail ice particles at typical aircraft cruise altitudes. During
the CIRRUS-III campaign cirrus clouds and almost 40 persistent contrails were
probed with in situ instruments over Germany and Northern Europe in November
2006. Besides reactive nitrogen, water vapor, cloud ice water content, ice
particle size distributions, and condensation nuclei were measured during 6
flights. Contrails with ages up to 12 h were detected at altitudes
10–11.5 km and temperatures 211–220 K. These contrails
had a larger ice phase fraction of total nitric acid
(HNO3ice/HNO3tot = 6%) than the ambient
cirrus layers (3%). On average, the contrails contained twice as much
HNO3ice as the cirrus clouds, 14 pmol/mol and
6 pmol/mol, respectively. Young contrails with ages below 1 h
had a mean HNO3ice of 21 pmol/mol. The contrails had
higher nitric acid to water molar ratios in ice and slightly higher ice water
contents than the cirrus clouds under similar meteorological conditions. The
differences in ice phase fractions and molar ratios between developing
contrails and cirrus are likely caused by high plume concentrations of
HNO3 prior to contrail formation. The location of the measurements
in the upper region of frontal cirrus layers might account for slight
differences in the ice water content between contrails and adjacent cirrus
clouds. The observed dependence of molar ratios as a function of the mean ice
particle diameter suggests that ice-bound HNO3 concentrations are
controlled by uptake of exhaust HNO3 in the freezing plume aerosols
in young contrails and subsequent trapping of ambient HNO3 in
growing ice particles in older (age > 1 h) contrails. |
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