The ice selective inlet. a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds
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Authors
Kupiszewski, Piotr
Vochezer, Paul
Schnaiter, Martin
Bigi, Alessandro
Rosati, Bernadette
Toprak, Emre
Mertes, Stephan
Baltensperger, Urs
Author (Corporation)
Publication date
2015
Typ of student thesis
Course of study
Collections
Type
01A - Journal article
Editors
Editor (Corporation)
Supervisor
Parent work
Atmospheric Measurement Techniques
Special issue
DOI of the original publication
Link
Series
Series number
Volume
8
Issue / Number
8
Pages / Duration
3087–3106
Patent number
Publisher / Publishing institution
Copernicus
Place of publication / Event location
Göttingen
Edition
Version
Programming language
Assignee
Practice partner / Client
Abstract
Climate predictions are affected by high uncertainties partially due to an insufficient knowledge of aerosol–cloud interactions. One of the poorly understood processes is formation of mixed-phase clouds (MPCs) via heterogeneous ice nucleation. Field measurements of the atmospheric ice phase in MPCs are challenging due to the presence of much more numerous liquid droplets. The Ice Selective Inlet (ISI), presented in this paper, is a novel inlet designed to selectively sample pristine ice crystals in mixed-phase clouds and extract the ice residual particles contained within the crystals for physical and chemical characterization. Using a modular setup composed of a cyclone impactor, droplet evaporation unit and pumped counterflow virtual impactor (PCVI), the ISI segregates particles based on their inertia and phase, exclusively extracting small ice particles between 5 and 20 μm in diameter. The setup also includes optical particle spectrometers for analysis of the number size distribution and shape of the sampled hydrometeors. The novelty of the ISI is a droplet evaporation unit, which separates liquid droplets and ice crystals in the airborne state, thus avoiding physical impaction of the hydrometeors and limiting potential artefacts. The design and validation of the droplet evaporation unit is based on modelling studies of droplet evaporation rates and computational fluid dynamics simulations of gas and particle flows through the unit. Prior to deployment in the field, an inter-comparison of the optical particle size spectrometers and a characterization of the transmission efficiency of the PCVI was conducted in the laboratory. The ISI was subsequently deployed during the Cloud and Aerosol Characterization Experiment (CLACE) 2013 and 2014 – two extensive international field campaigns encompassing comprehensive measurements of cloud microphysics, as well as bulk aerosol, ice residual and ice nuclei properties. The campaigns provided an important opportunity for a proof of concept of the inlet design. In this work we present the setup of the ISI, including the modelling and laboratory characterization of its components, as well as field measurements demonstrating the ISI performance and validating the working principle of the inlet. Finally, measurements of biological aerosol during a Saharan dust event (SDE) are presented, showing a first indication of enrichment of bio-material in sub-2 μm ice residuals.
Keywords
Subject (DDC)
620 - Ingenieurwissenschaften und Maschinenbau
Event
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ISBN
ISSN
1867-8548
1867-1381
1867-1381
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
Citation
KUPISZEWSKI, Piotr, Ernest WEINGARTNER, Paul VOCHEZER, Martin SCHNAITER, Alessandro BIGI, Martin GYSEL, Bernadette ROSATI, Emre TOPRAK, Stephan MERTES und Urs BALTENSPERGER, 2015. The ice selective inlet. a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds. Atmospheric Measurement Techniques. 2015. Bd. 8, Nr. 8, S. 3087–3106. DOI 10.5194/amt-8-3087-2015. Verfügbar unter: https://doi.org/10.26041/fhnw-8095