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In-situ observations and modeling of small nitric acid-containing ice crystals

Voigt, Christiane and Kärcher, Bernd and Schlager, Hans and Schiller, Cornelius and Krämer, Martina and Vössing, Hermann and DeReus, Marian and Borrmann, Stephan and Mitev, Valentin (2007) In-situ observations and modeling of small nitric acid-containing ice crystals. Atmospheric Chemistry and Physics, 7, pp. 3373-3383.

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Official URL: http://www.atmos-chem-phys.net/7/3373/2007/acp-7-3373-2007.html


Measurements in nascent ice forming regions are very rare and help understand cirrus cloud formation and the interactions of trace gases with ice crystals. A tenuous cirrus cloud has been probed with in-situ and remote sensing instruments onboard the high altitude research aircraft Geophysica M55 in the tropical upper troposphere. Besides microphysical and optical particle properties, water (H<sub>2</sub>O) and reactive nitrogen species (NOy) have been measured. In slightly ice supersaturated air between 14.2 and 14.9 km altitude, an unusually low ice water content of 0.031 mg m−3 and small ice crystals with mean radii of 5 µm have been detected. A high nitric acid to water molar ratio (HNO<sub>3</sub>/H<sub>2</sub>O) of 5.4×10−5 has been observed in the ice crystals, about an order of magnitude higher compared to previous observations in cirrus at temperatures near 202 K. A model describing the trapping of HNO<sub>3</sub> in growing ice particles shows that a high HNO3 content in ice crystals is expected during early growth stages, mainly originating from uptake in aerosol particles prior to freezing. Water vapor deposition on ice crystals and trapping of additional HNO3 reduces the molar ratio to values close to the ratio of HNO<sub>3</sub>/H<sub>2</sub>O in the gas phase while the cloud ages.

Document Type:Article
Title:In-situ observations and modeling of small nitric acid-containing ice crystals
AuthorsInstitution or Email of Authors
Voigt, ChristianeUNSPECIFIED
Schiller, CorneliusFZ Jülich, Jülich
Krämer, MartinaFZ Jülich, Jülich
Vössing, HermannUniv. Mainz, Mainz
DeReus, MarianUniv. Mainz, Mainz
Borrmann, StephanMPI für Chemie, Mainz
Mitev, ValentinUniv. Neuchâtel, Neuchâtel, CH
Date:June 2007
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
In Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 3373-3383
Keywords:cirrus, nitric acid, trace gas uptake, ice
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Projekt Partikel und Zirren II (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Atmospheric Trace Species
Deposited By: Dr.rer.nat. Christiane Voigt
Deposited On:05 Jul 2007
Last Modified:20 Oct 2014 14:31

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