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Insights into the role of soot aerosols in cirrus cloud formation

Kärcher, Bernd und Möhler, Ottmar und DeMott, Paul J. und Pechtl, Susanne und Yu, Fangqun (2007) Insights into the role of soot aerosols in cirrus cloud formation. Atmospheric Chemistry and Physics, 7, Seiten 4203-4227.

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Offizielle URL: http://www.atmos-chem-phys.net/7/4203/2007/acp-7-4203-2007.pdf

Kurzfassung

Cirrus cloud formation is believed to be domi-nated by homogeneous freezing of supercooled liquid aerosols in many instances. Heterogeneous ice nuclei such as mineral dust, metallic, and soot particles, and some crystalline solids within partially soluble aerosols are suspected to modulate cirrus properties. Among those, the role of ubiqui-tous soot particles is perhaps the least understood. Because aviation is a major source of upper tropospheric soot particles, we put emphasis on ice formation in dispersing aircraft plumes. The effect of aircraft soot on cirrus formation in the absence of contrails is highly complex and depends on a wide array of emission and environmental parameters. We use a microphysical-chemical model predicting the formation of internally mixed, soot-containing particles up to two days after emission, and suggest two principal scenarios: high concentrations of original soot emissions could slightly increase the number of ice crystals; low concentrations of particles originating from coagulation of emitted soot with background aerosols could lead to a significant reduction in ice crystal number. Both scenarios assume soot particles to be moderate ice nuclei relative to cirrus formation by homogeneous freezing in the presence of few efficient dust ice nuclei. A critical discussion of laboratory experiments reveals that the ice nucleation efficiency of soot particles depends strongly on their source, and, by inference, on atmospheric aging processes. Mass and chemistry of soluble surface coatings appear to be crucial factors. Immersed soot particles tend to be poor ice nuclei, some bare ones nucleate ice at low supersaturations. However, a fundamental understanding of these studies is lacking, rendering extrapolations to atmospheric conditions speculative. In particular, we cannot yet decide which indirect aircraft effect scenario is more plausible, and options suggested to mitigate the problem remain uncertain.

Dokumentart:Zeitschriftenbeitrag
Titel:Insights into the role of soot aerosols in cirrus cloud formation
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Kärcher, BerndNICHT SPEZIFIZIERT
Möhler, OttmarIMK-AAF, FZ Karlsruhe
DeMott, Paul J.Colorado State University, CO, USA
Pechtl, SusanneUniv. Heidelberg, Heidelberg
Yu, FangqunSUNY at Albany, NY, USA
Datum:17 August 2007
Erschienen in:Atmospheric Chemistry and Physics
Referierte Publikation:Ja
In Open Access:Ja
In SCOPUS:Ja
In ISI Web of Science:Ja
Band:7
Seitenbereich:Seiten 4203-4227
Status:veröffentlicht
Stichwörter:soot, cirrus, aviation
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Luftfahrt
HGF - Programmthema:L VU - Luftverkehr und Umwelt (alt)
DLR - Schwerpunkt:Luftfahrt
DLR - Forschungsgebiet:L VU - Luftverkehr und Umwelt
DLR - Teilgebiet (Projekt, Vorhaben):L - Schadstoffarmer Luftverkehr (alt)
Standort: Oberpfaffenhofen
Institute & Einrichtungen:Institut für Physik der Atmosphäre > Atmosphärische Spurenstoffe
Hinterlegt von: Prof. Bernd Kärcher
Hinterlegt am:22 Aug 2007
Letzte Änderung:20 Okt 2014 14:32

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