Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch
The scavenging of black carbon (BC) in liquid and mixed phase clouds was investigated during intensive experiments in winter 2004, summer 2004 and winter 2005 at the high alpine research station Jungfraujoch (3580 m a.s.l., Switzerland). Aerosol residuals were sampled behind two well characterized i...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2007-01-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/7/1797/2007/acp-7-1797-2007.pdf |
| _version_ | 1818874155563483136 |
|---|---|
| author | J. Cozic B. Verheggen B. Verheggen S. Mertes P. Connolly K. Bower A. Petzold U. Baltensperger E. Weingartner |
| author_facet | J. Cozic B. Verheggen B. Verheggen S. Mertes P. Connolly K. Bower A. Petzold U. Baltensperger E. Weingartner |
| author_sort | J. Cozic |
| collection | DOAJ |
| description | The scavenging of black carbon (BC) in liquid and mixed phase clouds was investigated during intensive experiments in winter 2004, summer 2004 and winter 2005 at the high alpine research station Jungfraujoch (3580 m a.s.l., Switzerland). Aerosol residuals were sampled behind two well characterized inlets; a total inlet which collected cloud particles (droplets and ice particles) as well as interstitial (unactivated) aerosol particles; an interstitial inlet which collected only interstitial aerosol particles. BC concentrations were measured behind each of these inlets along with the submicrometer aerosol number size distribution, from which a volume concentration was derived. These measurements were complemented by in-situ measurements of cloud microphysical parameters. BC was found to be scavenged into the condensed phase to the same extent as the bulk aerosol, which suggests that BC was covered with soluble material through aging processes, rendering it more hygroscopic. The scavenged fraction of BC (<I>F</I><sub>Scav,BC</sub>), defined as the fraction of BC that is incorporated into cloud droplets and ice crystals, decreases with increasing cloud ice mass fraction (IMF) from <I>F</I><sub>Scav,BC</sub>=60% in liquid phase clouds to F<sub>Scav,BC</sub>~5–10% in mixed-phase clouds with IMF>0.2. This can be explained by the evaporation of liquid droplets in the presence of ice crystals (Wegener-Bergeron-Findeisen process), releasing BC containing cloud condensation nuclei back into the interstitial phase. In liquid clouds, the scavenged BC fraction is found to decrease with decreasing cloud liquid water content. The scavenged BC fraction is also found to decrease with increasing BC mass concentration since there is an increased competition for the available water vapour. |
| first_indexed | 2024-12-19T13:06:06Z |
| format | Article |
| id | doaj.art-e1d348bb446b45da8773c46038d802fc |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-19T13:06:06Z |
| publishDate | 2007-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-e1d348bb446b45da8773c46038d802fc2022-12-21T20:20:04ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242007-01-017717971807Scavenging of black carbon in mixed phase clouds at the high alpine site JungfraujochJ. CozicB. VerheggenB. VerheggenS. MertesP. ConnollyK. BowerA. PetzoldU. BaltenspergerE. WeingartnerThe scavenging of black carbon (BC) in liquid and mixed phase clouds was investigated during intensive experiments in winter 2004, summer 2004 and winter 2005 at the high alpine research station Jungfraujoch (3580 m a.s.l., Switzerland). Aerosol residuals were sampled behind two well characterized inlets; a total inlet which collected cloud particles (droplets and ice particles) as well as interstitial (unactivated) aerosol particles; an interstitial inlet which collected only interstitial aerosol particles. BC concentrations were measured behind each of these inlets along with the submicrometer aerosol number size distribution, from which a volume concentration was derived. These measurements were complemented by in-situ measurements of cloud microphysical parameters. BC was found to be scavenged into the condensed phase to the same extent as the bulk aerosol, which suggests that BC was covered with soluble material through aging processes, rendering it more hygroscopic. The scavenged fraction of BC (<I>F</I><sub>Scav,BC</sub>), defined as the fraction of BC that is incorporated into cloud droplets and ice crystals, decreases with increasing cloud ice mass fraction (IMF) from <I>F</I><sub>Scav,BC</sub>=60% in liquid phase clouds to F<sub>Scav,BC</sub>~5–10% in mixed-phase clouds with IMF>0.2. This can be explained by the evaporation of liquid droplets in the presence of ice crystals (Wegener-Bergeron-Findeisen process), releasing BC containing cloud condensation nuclei back into the interstitial phase. In liquid clouds, the scavenged BC fraction is found to decrease with decreasing cloud liquid water content. The scavenged BC fraction is also found to decrease with increasing BC mass concentration since there is an increased competition for the available water vapour.http://www.atmos-chem-phys.net/7/1797/2007/acp-7-1797-2007.pdf |
| spellingShingle | J. Cozic B. Verheggen B. Verheggen S. Mertes P. Connolly K. Bower A. Petzold U. Baltensperger E. Weingartner Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch Atmospheric Chemistry and Physics |
| title | Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch |
| title_full | Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch |
| title_fullStr | Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch |
| title_full_unstemmed | Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch |
| title_short | Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch |
| title_sort | scavenging of black carbon in mixed phase clouds at the high alpine site jungfraujoch |
| url | http://www.atmos-chem-phys.net/7/1797/2007/acp-7-1797-2007.pdf |
| work_keys_str_mv | AT jcozic scavengingofblackcarboninmixedphasecloudsatthehighalpinesitejungfraujoch AT bverheggen scavengingofblackcarboninmixedphasecloudsatthehighalpinesitejungfraujoch AT bverheggen scavengingofblackcarboninmixedphasecloudsatthehighalpinesitejungfraujoch AT smertes scavengingofblackcarboninmixedphasecloudsatthehighalpinesitejungfraujoch AT pconnolly scavengingofblackcarboninmixedphasecloudsatthehighalpinesitejungfraujoch AT kbower scavengingofblackcarboninmixedphasecloudsatthehighalpinesitejungfraujoch AT apetzold scavengingofblackcarboninmixedphasecloudsatthehighalpinesitejungfraujoch AT ubaltensperger scavengingofblackcarboninmixedphasecloudsatthehighalpinesitejungfraujoch AT eweingartner scavengingofblackcarboninmixedphasecloudsatthehighalpinesitejungfraujoch |