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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2017-474
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
29 May 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
The Horizontal Ice Nucleation Chamber HINC: INP measurements at Conditions Relevant for Mixed-Phase Clouds at the High Altitude Research Station Jungfraujoch
Larissa Lacher1, Ulrike Lohmann1, Yvonne Boose1,a, Assaf Zipori2,b, Erik Herrmann3, Nicolas Bukowiecki3, Martin Steinbacher4, and Zamin A. Kanji1 1Institute for Atmospheric and Climate Science, ETHZ, Zurich, 8092, Switzerland
2Institute for Earth Science, Hebrew University, Jerusalem, 76100, Israel
3Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, 5232, Switzerland
4Empa, Swiss Federal Laboratories for Materials Science and Technology, Duebendorf, 8600, Switzerland
anow at: Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research, Garmisch-Partenkirchen, 82467, Germany
bnow at: Weizmann Institute of Science, Department of Earth and Planetary Sciences, Rehovot, 7610001, Israel
Abstract. In this work we describe the Horizontal Ice Nucleation Chamber, HINC as a new instrument to measure ambient ice nucleating particle (INP) concentrations for conditions relevant to mixed-phase clouds. Laboratory verification and validation experiments confirm accuracy of the thermodynamic conditions of temperature (T) and relative humidity (RH) in HINC with uncertainties in temperature of ±0.4 K and in RH with respect to water (RHw) of ±1.5 %, which translates to an uncertainty in RH with respect to ice (RHi) of ±3.0 % at T > 235 K. For further validation of HINC as a field instrument, two measurement campaigns were conducted in winters 2015 and 2016 at the High Altitude Research Station Jungfraujoch (JFJ; Switzerland, 3580 m a.s.l.) to sample ambient INPs. During winters 2015 and 2016 the site encountered free tropospheric conditions 92 % and 79 % of the time respectively. We measured INP concentrations at 242 K at water sub-saturated conditions (RHw = 94 %), relevant for the formation of ice clouds, and in the water supersaturated regime (RHw = 103–104 %) to represent ice formation occurring under mixed-phase cloud conditions. In winter 2015 and 2016 the median INP concentrations at RHw = 94 % was below the minimum detectable concentration. At RHw = 104 %, INP concentrations were an order of magnitude higher, with median concentrations in winter 2015 of 2.8 per standard liter (stdL−1; normalized to standard temperature T = 273 K and pressure p = 1013 hPa) and 4.7 stdL−1 in winter 2016. The measurements are in agreement with previous winter measurements obtained with the Portable Ice Nucleation Chamber, PINC, of 2.2 stdL−1 at the same location. During winter 2015, two events caused the INP concentrations at RHw = 103–104 % to significantly increase above the campaign average. First, an increase to 72.1 stdL−1 was measured during an event influenced by marine air, coming from the Northern Sea and the Norwegian Sea. Second, INP concentrations up to 146.2 stdL−1 were observed during a Saharan dust event. To our knowledge this is the first time that a clear enrichment in ambient INP concentration is observed during a time of marine air mass influence, indicating the importance of marine particles on ice nucleation in the free troposphere.

Citation: Lacher, L., Lohmann, U., Boose, Y., Zipori, A., Herrmann, E., Bukowiecki, N., Steinbacher, M., and Kanji, Z. A.: The Horizontal Ice Nucleation Chamber HINC: INP measurements at Conditions Relevant for Mixed-Phase Clouds at the High Altitude Research Station Jungfraujoch, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-474, in review, 2017.
Larissa Lacher et al.
Larissa Lacher et al.
Larissa Lacher et al.

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Short summary
We characterize the new Horizontal Ice Nucleation Chamber HINC to measure ambient ice nucleating particle concentrations at mixed-phase cloud conditions. Results from winter measurements at the High Altitude Research Station Jungfraujoch compare well to previous measurements. We find increased ice nucleating particle concentrations during the influence of Saharan dust and marine aerosols, which highlights the importance of these species on ice nucleation in the free troposphere.
We characterize the new Horizontal Ice Nucleation Chamber HINC to measure ambient ice nucleating...
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