Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.)
Aerosols influence the Earth's radiation budget directly through absorption and scattering of solar radiation in the atmosphere but also indirectly by modifying the properties of clouds. However, climate models still suffer from large uncertainties as a result of insufficient understand...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2014-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/14/1123/2014/acp-14-1123-2014.pdf |
| _version_ | 1818290024695726080 |
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| author | E. Hammer N. Bukowiecki M. Gysel Z. Jurányi C. R. Hoyle R. Vogt U. Baltensperger E. Weingartner |
| author_facet | E. Hammer N. Bukowiecki M. Gysel Z. Jurányi C. R. Hoyle R. Vogt U. Baltensperger E. Weingartner |
| author_sort | E. Hammer |
| collection | DOAJ |
| description | Aerosols influence the Earth's radiation budget directly through
absorption and scattering of solar radiation in the atmosphere but
also indirectly by modifying the properties of clouds. However,
climate models still suffer from large uncertainties as a result of
insufficient understanding of aerosol-cloud interactions. At the
high altitude research station Jungfraujoch (JFJ;
3580 m a.s.l., Switzerland) cloud condensation nuclei (CCN)
number concentrations at eight different supersaturations (SS) from
0.24% to 1.18% were measured using a CCN counter during
Summer 2011. Simultaneously, in-situ aerosol activation properties
of the prevailing ambient clouds were investigated by measuring the
total and interstitial (non-activated) dry particle number size
distributions behind two different inlet systems. Combining all
experimental data, a new method was developed to retrieve the
so-called effective peak supersaturation SS<sub>peak</sub>,
as a measure of the SS at which ambient clouds are
formed. A 17-month CCN climatology was then used to retrieve the
SS<sub>peak</sub> values also for four earlier summer
campaigns (2000, 2002, 2004 and 2010) where no direct CCN data were
available. The SS<sub>peak</sub> values varied between
0.01% and 2.0% during all campaigns. An overall median
SS<sub>peak</sub> of 0.35% and dry activation diameter
of 87 nm was observed. It was found that the difference in
topography between northwest and southeast plays an important role
for the effective peak supersaturation in clouds formed in the
vicinity of the JFJ, while differences in the number concentration
of potential CCN only play a minor role. Results show that air
masses coming from the southeast (with the slowly rising terrain of
the Aletsch Glacier) generally experience lower
SS<sub>peak</sub> values than air masses coming from the
northwest (steep slope). The observed overall median values were
0.41% and 0.22% for northwest and southeast wind
conditions, respectively, corresponding to literature values for
cumulus clouds and shallow-layer clouds. These cloud types are
consistent with weather observations routinely performed at the JFJ. |
| first_indexed | 2024-12-13T02:21:36Z |
| format | Article |
| id | doaj.art-39789985c82d42ebafe048131466abda |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-13T02:21:36Z |
| publishDate | 2014-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-39789985c82d42ebafe048131466abda2022-12-22T00:02:45ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242014-01-011421123113910.5194/acp-14-1123-2014Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.)E. Hammer0N. Bukowiecki1M. Gysel2Z. Jurányi3C. R. Hoyle4R. Vogt5U. Baltensperger6E. Weingartner7Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, SwitzerlandLaboratory of Atmospheric Chemistry, Paul Scherrer Institute, SwitzerlandLaboratory of Atmospheric Chemistry, Paul Scherrer Institute, SwitzerlandLaboratory of Atmospheric Chemistry, Paul Scherrer Institute, SwitzerlandLaboratory of Atmospheric Chemistry, Paul Scherrer Institute, SwitzerlandMeteorology, Climatology and Remote Sensing, University of Basel, SwitzerlandLaboratory of Atmospheric Chemistry, Paul Scherrer Institute, SwitzerlandLaboratory of Atmospheric Chemistry, Paul Scherrer Institute, SwitzerlandAerosols influence the Earth's radiation budget directly through absorption and scattering of solar radiation in the atmosphere but also indirectly by modifying the properties of clouds. However, climate models still suffer from large uncertainties as a result of insufficient understanding of aerosol-cloud interactions. At the high altitude research station Jungfraujoch (JFJ; 3580 m a.s.l., Switzerland) cloud condensation nuclei (CCN) number concentrations at eight different supersaturations (SS) from 0.24% to 1.18% were measured using a CCN counter during Summer 2011. Simultaneously, in-situ aerosol activation properties of the prevailing ambient clouds were investigated by measuring the total and interstitial (non-activated) dry particle number size distributions behind two different inlet systems. Combining all experimental data, a new method was developed to retrieve the so-called effective peak supersaturation SS<sub>peak</sub>, as a measure of the SS at which ambient clouds are formed. A 17-month CCN climatology was then used to retrieve the SS<sub>peak</sub> values also for four earlier summer campaigns (2000, 2002, 2004 and 2010) where no direct CCN data were available. The SS<sub>peak</sub> values varied between 0.01% and 2.0% during all campaigns. An overall median SS<sub>peak</sub> of 0.35% and dry activation diameter of 87 nm was observed. It was found that the difference in topography between northwest and southeast plays an important role for the effective peak supersaturation in clouds formed in the vicinity of the JFJ, while differences in the number concentration of potential CCN only play a minor role. Results show that air masses coming from the southeast (with the slowly rising terrain of the Aletsch Glacier) generally experience lower SS<sub>peak</sub> values than air masses coming from the northwest (steep slope). The observed overall median values were 0.41% and 0.22% for northwest and southeast wind conditions, respectively, corresponding to literature values for cumulus clouds and shallow-layer clouds. These cloud types are consistent with weather observations routinely performed at the JFJ.http://www.atmos-chem-phys.net/14/1123/2014/acp-14-1123-2014.pdf |
| spellingShingle | E. Hammer N. Bukowiecki M. Gysel Z. Jurányi C. R. Hoyle R. Vogt U. Baltensperger E. Weingartner Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.) Atmospheric Chemistry and Physics |
| title | Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.) |
| title_full | Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.) |
| title_fullStr | Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.) |
| title_full_unstemmed | Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.) |
| title_short | Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.) |
| title_sort | investigation of the effective peak supersaturation for liquid phase clouds at the high alpine site jungfraujoch switzerland 3580 m a s l |
| url | http://www.atmos-chem-phys.net/14/1123/2014/acp-14-1123-2014.pdf |
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