Sensitivity estimations for cloud droplet formation in the vicinity of the high-alpine research station Jungfraujoch (3580 m a.s.l.)
Loading...
Authors
Hammer, Emanuel
Bukowiecki, Nicolas
Luo, Beiping
Lohmann, Ulrike
Marcolli, Claudia
Baltensperger, Urs
Hoyle, Christopher R.
Author (Corporation)
Publication date
2015
Typ of student thesis
Course of study
Collections
Type
01A - Journal article
Editors
Editor (Corporation)
Supervisor
Parent work
Atmospheric Chemistry and Physics
Special issue
DOI of the original publication
Link
Series
Series number
Volume
15
Issue / Number
18
Pages / Duration
10309–10323
Patent number
Publisher / Publishing institution
Copernicus
Place of publication / Event location
Göttingen
Edition
Version
Programming language
Assignee
Practice partner / Client
Abstract
Aerosol 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.
Keywords
Subject (DDC)
550 - Geowissenschaften
Event
Exhibition start date
Exhibition end date
Conference start date
Conference end date
Date of the last check
ISBN
ISSN
1680-7324
1680-7316
1680-7316
Language
English
Created during FHNW affiliation
Yes
Strategic action fields FHNW
Publication status
Published
Review
Peer review of the complete publication
Open access category
Gold
License
Citation
HAMMER, Emanuel, Nicolas BUKOWIECKI, Beiping LUO, Ulrike LOHMANN, Claudia MARCOLLI, Ernest WEINGARTNER, Urs BALTENSPERGER und Christopher R. HOYLE, 2015. Sensitivity estimations for cloud droplet formation in the vicinity of the high-alpine research station Jungfraujoch (3580 m a.s.l.). Atmospheric Chemistry and Physics. 2015. Bd. 15, Nr. 18, S. 10309–10323. DOI 10.5194/acp-15-10309-2015. Verfügbar unter: https://doi.org/10.26041/fhnw-8092