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dc.contributor.author
Brabec, Martin
dc.contributor.author
Wienhold, Frank G.
dc.contributor.author
Luo, Beiping P.
dc.contributor.author
Vömel, Holger
dc.contributor.author
Immler, Franz
dc.contributor.author
Steiner, Philippe
dc.contributor.author
Hausammann, Edwin
dc.contributor.author
Weers, Uwe
dc.contributor.author
Peter, Thomas
dc.date.accessioned
2018-11-05T11:57:19Z
dc.date.available
2017-06-10T10:26:13Z
dc.date.available
2018-11-05T11:57:19Z
dc.date.issued
2012
dc.identifier.issn
1680-7375
dc.identifier.issn
1680-7367
dc.identifier.other
10.5194/acp-12-9135-2012
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/57693
dc.identifier.doi
10.3929/ethz-b-000057693
dc.description.abstract
Advanced measurement and modelling techniques are employed to estimate the partitioning of atmospheric water between the gas phase and the condensed phase in and around cirrus clouds, and thus to identify in-cloud and out-of-cloud supersaturations with respect to ice. In November 2008 the newly developed balloon-borne backscatter sonde COBALD (Compact Optical Backscatter and AerosoL Detector) was flown 14 times together with a CFH (Cryogenic Frost point Hygrometer) from Lindenberg, Germany (52° N, 14° E). The case discussed here in detail shows two cirrus layers with in-cloud relative humidities with respect to ice between 50% and 130%. Global operational analysis data of ECMWF (roughly 1° × 1° horizontal and 1 km vertical resolution, 6-hourly stored fields) fail to represent ice water contents and relative humidities. Conversely, regional COSMO-7 forecasts (6.6 km × 6.6 km, 5-min stored fields) capture the measured humidities and cloud positions remarkably well. The main difference between ECMWF and COSMO data is the resolution of small-scale vertical features responsible for cirrus formation. Nevertheless, ice water contents in COSMO-7 are still off by factors 2–10, likely reflecting limitations in COSMO's ice phase bulk scheme. Significant improvements can be achieved by comprehensive size-resolved microphysical and optical modelling along backward trajectories based on COSMO-7 wind and temperature fields, which allow accurate computation of humidities, homogeneous ice nucleation, resulting ice particle size distributions and backscatter ratios at the COBALD wavelengths. However, only by superimposing small-scale temperature fluctuations, which remain unresolved by the numerical weather prediction models, can we obtain a satisfying agreement with the observations and reconcile the measured in-cloud non-equilibrium humidities with conventional ice cloud microphysics. Conversely, the model-data comparison provides no evidence that additional changes to ice-cloud microphysics – such as heterogeneous nucleation or changing the water vapour accommodation coefficient on ice – are required.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
Copernicus
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/3.0/
dc.title
Particle backscatter and relative humidity measured across cirrus clouds and comparison with microphysical cirrus modelling
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 3.0 Unported
dc.date.published
2012-10-05
ethz.journal.title
Atmospheric Chemistry and Physics
ethz.journal.volume
12
en_US
ethz.journal.issue
19
en_US
ethz.journal.abbreviated
Atmos. chem. phys.
ethz.pages.start
9135
en_US
ethz.pages.end
9148
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.identifier.wos
ethz.identifier.nebis
004294181
ethz.publication.place
Göttingen
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02717 - Institut für Atmosphäre und Klima / Inst. Atmospheric and Climate Science::03517 - Peter, Thomas / Peter, Thomas
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02717 - Institut für Atmosphäre und Klima / Inst. Atmospheric and Climate Science::03517 - Peter, Thomas / Peter, Thomas
ethz.date.deposited
2017-06-10T10:28:41Z
ethz.source
ECIT
ethz.identifier.importid
imp59364febbe24823831
ethz.ecitpid
pub:92342
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-07-26T20:58:44Z
ethz.rosetta.lastUpdated
2021-02-15T02:23:45Z
ethz.rosetta.versionExported
true
ethz.COinS
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