Investigating fluctuations in ice nucleating particle concentrations over orographic terrain
OPEN ACCESS
Loading...
Author / Producer
Date
2019-09-19
Publication Type
Bachelor Thesis
ETH Bibliography
yes
Citations
Altmetric
OPEN ACCESS
Data
Rights / License
Abstract
Ice particles influence the radiation and lifetime of cirrus and mixed-phase clouds and initiate most of global precipitation. Processes like heterogeneous ice nucleation responsible for the formation of first ice in clouds are still not completely understood and contribute to uncertainties in weather and climate modelling. RACLETS (Role of Aerosols and Clouds Enhanced by Topography on Snow) was a field campaign planned in order to investigate the whole formation and deposition pathway of precipitation in Davos, Switzerland, in February and March 2019. The aim of this thesis was to investigate if and how ice nucleating particle concentrations ([INP]) at −8◦C and −15◦C fluctuated over orographic terrain at the measurement site in the valley (Wolfgangpass (WOP), 1631 m a.s.l.) compared to on the mountain top (Weissfluhjoch (WFJ), 2691 m a.s.l.). The [INP] were measured with the drop freezing apparatus DRINCZ (DRoplet Ice Nucleation Counter Zurich) and LINDA (LED-based Ice Nucleation Detection Apparatus). Measurements taken during a clear sky and dry period were compared to a period with frequent occurrence of clouds and precipitation. The influence on the [INP] of a Saharan dust event from long range transport as well as local processes (presence of snowfall, inversion layers and emission of biological particles) were examined. A significant increase of [INP] was observed during the Saharan dust event at −15◦C at WFJ, but not at WOP. During snow- fall as well as sunny and warm periods after midday (12:00 to 14:00 local time), [INP] increased significantly at −8◦C on both sites. Particles enhancing the ice nucleation at −8◦C are thought to be of biological origin. Despite the significant influence on [INP] during hours or days, the mean of the two investigated periods of time did not differ. Therefore, the importance of a correct parameterization with a high temporal resolution of the [INP] for short term applications like weather predictions is proposed, but not for longer time scales of climate modelling.
Permanent link
Publication status
published
External links
Editor
Contributors
Examiner: Wieder, Jörg
Examiner: Kanji, Zamin
Book title
Journal / series
Volume
Pages / Article No.
Publisher
ETH Zurich
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
aerosol; INP; ice nucleation; Alps; orographic clouds; mixed-phase clouds; snowfall; precipitation
Organisational unit
02717 - Institut für Atmosphäre und Klima / Inst. Atmospheric and Climate Science
Notes
Funding
Related publications and datasets
Is continued by: