Sensitivity estimations for cloud droplet formation in the vicinity of the high-alpine research station Jungfraujoch (3580 m a.s.l.)

dc.contributor.authorHammer, Emanuel
dc.contributor.authorBukowiecki, Nicolas
dc.contributor.authorLuo, Beiping
dc.contributor.authorLohmann, Ulrike
dc.contributor.authorMarcolli, Claudia
dc.contributor.authorWeingartner, Ernest
dc.contributor.authorBaltensperger, Urs
dc.contributor.authorHoyle, Christopher R.
dc.date.accessioned2024-02-08T08:57:04Z
dc.date.available2024-02-08T08:57:04Z
dc.date.issued2015
dc.description.abstractAerosol radiative forcing estimates suffer from large uncertainties as a result of insufficient understanding of aerosol–cloud interactions. The main source of these uncertainties is dynamical processes such as turbulence and entrainment but also key aerosol parameters such as aerosol number concentration and size distribution, and to a much lesser extent, the composition. From June to August 2011 a Cloud and Aerosol Characterization Experiment (CLACE2011) was performed at the high-alpine research station Jungfraujoch (Switzerland, 3580 m a.s.l.) focusing on the activation of aerosol to form liquid-phase clouds (in the cloud base temperature range of −8 to 5 °C). With a box model the sensitivity of the effective peak supersaturation (SSpeak), an important parameter for cloud activation, to key aerosol and dynamical parameters was investigated. The updraft velocity, which defines the cooling rate of an air parcel, was found to have the greatest influence on SSpeak. Small-scale variations in the cooling rate with large amplitudes can significantly alter CCN activation. Thus, an accurate knowledge of the air parcel history is required to estimate SSpeak. The results show that the cloud base updraft velocities estimated from the horizontal wind measurements made at the Jungfraujoch can be divided by a factor of approximately 4 to get the updraft velocity required for the model to reproduce the observed SSpeak. The aerosol number concentration and hygroscopic properties were found to be less important than the aerosol size in determining SSpeak. Furthermore turbulence is found to have a maximum influence when SSpeak is between approximately 0.2 and 0.4 %. Simulating the small-scale fluctuations with several amplitudes, frequencies and phases, revealed that independently of the amplitude, the effect of the frequency on SSpeak shows a maximum at 0.46 Hz (median over all phases) and at higher frequencies, the maximum SSpeak decreases again.
dc.identifier.doi10.5194/acp-15-10309-2015
dc.identifier.issn1680-7324
dc.identifier.issn1680-7316
dc.identifier.urihttps://irf.fhnw.ch/handle/11654/44282
dc.identifier.urihttps://doi.org/10.26041/fhnw-8092
dc.issue18
dc.language.isoen
dc.publisherCopernicus
dc.relation.ispartofAtmospheric Chemistry and Physics
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.spatialGöttingen
dc.subject.ddc550 - Geowissenschaften
dc.titleSensitivity estimations for cloud droplet formation in the vicinity of the high-alpine research station Jungfraujoch (3580 m a.s.l.)
dc.type01A - Beitrag in wissenschaftlicher Zeitschrift
dc.volume15
dspace.entity.typePublication
fhnw.InventedHereYes
fhnw.ReviewTypeAnonymous ex ante peer review of a complete publication
fhnw.affiliation.hochschuleHochschule für Technikde_CH
fhnw.affiliation.institutlnstitut für Sensorik und Elektronikde_CH
fhnw.openAccessCategoryGold
fhnw.pagination10309–10323
fhnw.publicationStatePublished
relation.isAuthorOfPublication05dd9a19-7a24-4325-805a-2d121483b168
relation.isAuthorOfPublication.latestForDiscovery05dd9a19-7a24-4325-805a-2d121483b168
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