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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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Volume 10, issue 2 | Copyright
Atmos. Meas. Tech., 10, 459-476, 2017
https://doi.org/10.5194/amt-10-459-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 06 Feb 2017

Research article | 06 Feb 2017

HoloGondel: in situ cloud observations on a cable car in the Swiss Alps using a holographic imager

Alexander Beck1, Jan Henneberger1, Sarah Schöpfer1, Jacob Fugal2, and Ulrike Lohmann1 Alexander Beck et al.
  • 1ETH Zurich, Institute for Atmospheric and Climate Science, Universitaetstrasse 16, 8092 Zurich, Switzerland
  • 2Johannes Gutenberg-Universitaet Mainz, Institute for Atmospheric Physics, J.-J.-Becherweg 21, 55099 Mainz, Germany

Abstract. In situ observations of cloud properties in complex alpine terrain where research aircraft cannot sample are commonly conducted at mountain-top research stations and limited to single-point measurements. The HoloGondel platform overcomes this limitation by using a cable car to obtain vertical profiles of the microphysical and meteorological cloud parameters. The main component of the HoloGondel platform is the HOLographic Imager for Microscopic Objects (HOLIMO 3G), which uses digital in-line holography to image cloud particles. Based on two-dimensional images the microphysical cloud parameters for the size range from small cloud particles to large precipitation particles are obtained for the liquid and ice phase. The low traveling velocity of a cable car on the order of 10ms−1 allows measurements with high spatial resolution; however, at the same time it leads to an unstable air speed towards the HoloGondel platform. Holographic cloud imagers, which have a sample volume that is independent of the air speed, are therefore well suited for measurements on a cable car. Example measurements of the vertical profiles observed in a liquid cloud and a mixed-phase cloud at the Eggishorn in the Swiss Alps in the winters 2015 and 2016 are presented. The HoloGondel platform reliably observes cloud droplets larger than 6.5µm, partitions between cloud droplets and ice crystals for a size larger than 25µm and obtains a statistically significantly size distribution for every 5m in vertical ascent.

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In situ observations of cloud properties in complex alpine terrain are commonly conducted at mountain-top research stations and limited to single-point measurements. The HoloGondel platform overcomes this limitation by using a cable car to obtain vertical profiles of the microphysical and meteorological cloud parameters. In this work example measurements of the vertical profiles observed in a liquid cloud and a mixed-phase cloud at the Eggishorn in the Swiss Alps are presented.
In situ observations of cloud properties in complex alpine terrain are commonly conducted at...
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