Show simple item record

dc.contributor.author
Croft, Betty
dc.contributor.author
Pierce, Jeffrey R.
dc.contributor.author
Martin, Randall V.
dc.contributor.author
Hoose, Corinna
dc.contributor.author
Lohmann, Ulrike
dc.date.accessioned
2018-11-05T12:50:03Z
dc.date.available
2017-06-10T12:07:58Z
dc.date.available
2018-11-05T12:50:03Z
dc.date.issued
2012
dc.identifier.issn
1680-7375
dc.identifier.issn
1680-7367
dc.identifier.other
10.5194/acp-12-10725-2012
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/60509
dc.identifier.doi
10.3929/ethz-b-000060509
dc.description.abstract
The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM) under a set of limiting assumptions for the wet removal of the entrained aerosols. The limiting assumptions for the wet removal of entrained aerosols are negligible scavenging and vigorous scavenging (either through activation, with size-dependent impaction scavenging, or with the prescribed fractions of the standard model). To facilitate this process-based study, an explicit representation of cloud-droplet-borne and ice-crystal-borne aerosol mass and number, for the purpose of wet removal, is introduced into the ECHAM5-HAM model. This replaces and is compared with the prescribed cloud-droplet-borne and ice-crystal-borne aerosol fraction scavenging scheme of the standard model. A 20% to 35% uncertainty in simulated global, annual mean aerosol mass burdens and optical depth (AOD) is attributed to different assumptions for the wet removal of aerosols entrained above convective cloud bases. Assumptions about the removal of aerosols entrained above convective cloud bases control modeled upper tropospheric aerosol concentrations by as much as one order of magnitude. Simulated aerosols entrained above convective cloud bases contribute 20% to 50% of modeled global, annual mean aerosol mass convective wet deposition (about 5% to 10% of the total dry and wet deposition), depending on the aerosol species, when including wet scavenging of those entrained aerosols (either by activation, size-dependent impaction, or with the prescribed fraction scheme). Among the simulations, the prescribed fraction and size-dependent impaction schemes yield the largest global, annual mean aerosol mass convective wet deposition (by about two-fold). However, the prescribed fraction scheme has more vigorous convective mixed-phase wet removal (by two to five-fold relative to the size-dependent impaction scheme) since nearly all entrained accumulation and coarse mode aerosols are assumed to be cloud-droplet borne or ice-crystal borne, and evaporation due to the Bergeron-Findeisen process is neglected. The simulated convective wet scavenging of entrained accumulation and coarse mode aerosols has feedbacks on new particle formation and the number of Aitken mode aerosols, which control stratiform and convective cloud droplet number concentrations and yield precipitation changes in the ECHAM5-HAM model. However, the geographic distribution of aerosol annual mean convective wet deposition change in the model is driven by changes to the assumptions regarding the scavenging of aerosols entrained above cloud bases rather than by precipitation changes, except for sea salt deposition in the tropics. Uncertainty in the seasonal, regional cycles of AOD due to assumptions about entrained aerosol wet scavenging is similar in magnitude to the estimated error in the AOD retrievals. The uncertainty in aerosol concentrations, burdens, and AOD attributed to different assumptions for the wet scavenging of aerosols entrained above convective cloud bases in a global model motivates the ongoing need to better understand and model the activation and impaction processes that aerosols undergo after entrainment into convective updrafts.
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
Uncertainty associated with convective wet removal of entrained aerosols in a global climate model
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 3.0 Unported
dc.date.published
2012-11-16
ethz.journal.title
Atmospheric Chemistry and Physics
ethz.journal.volume
12
en_US
ethz.journal.issue
22
en_US
ethz.journal.abbreviated
Atmos. chem. phys.
ethz.pages.start
10725
en_US
ethz.pages.end
10748
en_US
ethz.version.deposit
publishedVersion
en_US
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::03690 - Lohmann, Ulrike / Lohmann, Ulrike
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::03690 - Lohmann, Ulrike / Lohmann, Ulrike
ethz.date.deposited
2017-06-10T12:08:17Z
ethz.source
ECIT
ethz.identifier.importid
imp59365023b841c39972
ethz.ecitpid
pub:96617
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-07-26T18:27:24Z
ethz.rosetta.lastUpdated
2018-11-05T12:50:08Z
ethz.rosetta.versionExported
true
ethz.COinS
ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.atitle=Uncertainty%20associated%20with%20convective%20wet%20removal%20of%20entrained%20aerosols%20in%20a%20global%20climate%20model&rft.jtitle=Atmospheric%20Chemistry%20and%20Physics&rft.date=2012&rft.volume=12&rft.issue=22&rft.spage=10725&rft.epage=10748&rft.issn=1680-7375&1680-7367&rft.au=Croft,%20Betty&Pierce,%20Jeffrey%20R.&Martin,%20Randall%20V.&Hoose,%20Corinna&Lohmann,%20Ulrike&rft.genre=article&
 Search via SFX

Files in this item

Thumbnail

Publication type

Show simple item record