Articles | Volume 18, issue 1
https://doi.org/10.5194/amt-18-305-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/amt-18-305-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
16 Jan 2025
Research article |
| 16 Jan 2025
| 16 Jan 2025
Calibration of optical particle spectrometers using mounted fibres
Jessica Girdwood
CORRESPONDING AUTHOR
Centre for Atmospheric and Climate Physics, University of Hertfordshire, Hatfield, Hertfordshire, AL10 9AB, UK
now at: School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, M13 9PL, UK
now at: National Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, M13 9PL, UK
Harry Ballington
Centre for Atmospheric and Climate Physics, University of Hertfordshire, Hatfield, Hertfordshire, AL10 9AB, UK
Chris Stopford
Centre for Atmospheric and Climate Physics, University of Hertfordshire, Hatfield, Hertfordshire, AL10 9AB, UK
Rob Lewis
Centre for Atmospheric and Climate Physics, University of Hertfordshire, Hatfield, Hertfordshire, AL10 9AB, UK
Evelyn Hesse
Centre for Atmospheric and Climate Physics, University of Hertfordshire, Hatfield, Hertfordshire, AL10 9AB, UK
Related authors
Alexander Julian Böhmländer, Larissa Lacher, Kristina Höhler, David Brus, Konstantinos-Matthaios Doulgeris, Jessica Girdwood, Thomas Leisner, and Ottmar Möhler
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2025-87, https://doi.org/10.5194/essd-2025-87, 2025
Preprint under review for ESSD
Short summary
Short summary
Clouds play a key role in weather and climate. Pure liquid water droplets are liquid until about -35 °C without the presence of a small subset of aerosols, ice-nucleating particles (INPs). These INPs lead to primary ice formation and therefore impact the phase of clouds. The dataset described herein provides INP concentration measurements at two altitudes. Connecting this data to synoptic conditions and ambient data might provide a better understanding of INPs in Finnish Lapland.
Sina Jost, Ralf Weigel, Konrad Kandler, Luis Valero, Jessica Girdwood, Chris Stopford, Warren Stanley, Luca Katharina Eichhorn, Christian von Glahn, and Holger Tost
EGUsphere, https://doi.org/10.5194/egusphere-2025-451, https://doi.org/10.5194/egusphere-2025-451, 2025
This preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).
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For the balloon-borne detection of particles (diameter 0.4 < Dp < 40 µm), a Universal Cloud and Aerosol Sounding System (UCASS) was used, whose sample flow is determined by GPS-measured ascent rates. In flights, actual UCASS sample flows rarely match the ascent rates. Errors are minimized by real-time detection of the UCASS flows, e.g. by implementing a thermal flow sensor (TFS) within the UCASS. The TFSs were tested in flight, and calibrated at up to 10 m s-1 and at variable angles of attack.
Alexander Julian Böhmländer, Larissa Lacher, Kristina Höhler, David Brus, Konstantinos-Matthaios Doulgeris, Jessica Girdwood, Thomas Leisner, and Ottmar Möhler
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2025-87, https://doi.org/10.5194/essd-2025-87, 2025
Preprint under review for ESSD
Short summary
Short summary
Clouds play a key role in weather and climate. Pure liquid water droplets are liquid until about -35 °C without the presence of a small subset of aerosols, ice-nucleating particles (INPs). These INPs lead to primary ice formation and therefore impact the phase of clouds. The dataset described herein provides INP concentration measurements at two altitudes. Connecting this data to synoptic conditions and ambient data might provide a better understanding of INPs in Finnish Lapland.
Joseph Girdwood, Warren Stanley, Chris Stopford, and David Brus
Atmos. Meas. Tech., 15, 2061–2076, https://doi.org/10.5194/amt-15-2061-2022, https://doi.org/10.5194/amt-15-2061-2022, 2022
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UAVs have great potential to be used for airborne measurements of cloud and aerosol properties, which are of particular importance due to the largely uncharacterised nature of such phenomena. However, since UAVs are a new tool in atmospheric physics expensive platform validation and characterisation of UAV-instrument combinations needs to be performed. This paper presents an evaluation of a fixed-wing UAV in combination with an instrument that measures cloud droplet diameter.
Joseph Girdwood, Helen Smith, Warren Stanley, Zbigniew Ulanowski, Chris Stopford, Charles Chemel, Konstantinos-Matthaios Doulgeris, David Brus, David Campbell, and Robert Mackenzie
Atmos. Meas. Tech., 13, 6613–6630, https://doi.org/10.5194/amt-13-6613-2020, https://doi.org/10.5194/amt-13-6613-2020, 2020
Short summary
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We present the design and validation of an unmanned aerial vehicle (UAV) equipped with a bespoke optical particle counter (OPC). This is used to monitor atmospheric particles, which have significant effects on our weather and climate. These effects are hard to characterise properly, partly because they occur in regions that are not commonly accessible to traditional instrumentation. Our new platform gives us the capability to access these regions.
Helen R. Smith, Zbigniew Ulanowski, Paul H. Kaye, Edwin Hirst, Warren Stanley, Richard Kaye, Andreas Wieser, Chris Stopford, Maria Kezoudi, Joseph Girdwood, Richard Greenaway, and Robert Mackenzie
Atmos. Meas. Tech., 12, 6579–6599, https://doi.org/10.5194/amt-12-6579-2019, https://doi.org/10.5194/amt-12-6579-2019, 2019
Short summary
Short summary
The Universal Cloud and Aerosol Sounding System (UCASS) is a low-cost miniature optical particle counter (OPC) capable of sizing particles in the size range 0.4–40 μm. The open-geometry design makes the instrument suitable for deployment on balloon-borne sounding systems, dropsonde systems or as part of an unmanned aerial vehicle (UAV). Laboratory and field experiments show good agreement with reference instruments in a range of cloudy and dusty environments.
Fabian Mahrt, Jörg Wieder, Remo Dietlicher, Helen R. Smith, Chris Stopford, and Zamin A. Kanji
Atmos. Meas. Tech., 12, 3183–3208, https://doi.org/10.5194/amt-12-3183-2019, https://doi.org/10.5194/amt-12-3183-2019, 2019
Short summary
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A new instrument, the High Speed Particle Phase Discriminator (PPD-HS), is presented, with the goal of quantifying liquid and ice fraction in conditions relevant for mixed-phase clouds. PPD-HS captures the near-forward spatial intensity distribution of scattered light on a single particle basis. Symmetry analysis of the scattering pattern is used to determine the shape of the particles, with cloud droplets and ice crystals producing symmetrical and asymmetrical scattering patterns, respectively.
Z. Ulanowski, P. H. Kaye, E. Hirst, R. S. Greenaway, R. J. Cotton, E. Hesse, and C. T. Collier
Atmos. Chem. Phys., 14, 1649–1662, https://doi.org/10.5194/acp-14-1649-2014, https://doi.org/10.5194/acp-14-1649-2014, 2014
Related subject area
Subject: Clouds | Technique: Laboratory Measurement | Topic: Instruments and Platforms
Comment on “A universally applicable method of calculating confidence bands for ice nucleation spectra derived from droplet freezing experiments” by Fahy et al. (2022)
Icing wind tunnel measurements of supercooled large droplets using the 12 mm total water content cone of the Nevzorov probe
The Microfluidic Ice Nuclei Counter Zürich (MINCZ): a platform for homogeneous and heterogeneous ice nucleation
Effects of the large-scale circulation on temperature and water vapor distributions in the Π Chamber
Photoacoustic hygrometer for icing wind tunnel water content measurement: design, analysis, and intercomparison
SPIN modification for low-temperature experiments
Characterization and first results from LACIS-T: a moist-air wind tunnel to study aerosol–cloud–turbulence interactions
Low-temperature triple-capillary cryostat for ice crystal growth studies
A high-speed particle phase discriminator (PPD-HS) for the classification of airborne particles, as tested in a continuous flow diffusion chamber
The SPectrometer for Ice Nuclei (SPIN): an instrument to investigate ice nucleation
BINARY: an optical freezing array for assessing temperature and time dependence of heterogeneous ice nucleation
Experimental quantification of contact freezing in an electrodynamic balance
Application of linear polarized light for the discrimination of frozen and liquid droplets in ice nucleation experiments
Gabor Vali
Atmos. Meas. Tech., 16, 4303–4306, https://doi.org/10.5194/amt-16-4303-2023, https://doi.org/10.5194/amt-16-4303-2023, 2023
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Different methods for the calculation of nucleation spectra from drop-freezing experiments are discussed as the choice of data processing reflects on underlying principles.
Johannes Lucke, Tina Jurkat-Witschas, Romy Heller, Valerian Hahn, Matthew Hamman, Wolfgang Breitfuss, Venkateshwar Reddy Bora, Manuel Moser, and Christiane Voigt
Atmos. Meas. Tech., 15, 7375–7394, https://doi.org/10.5194/amt-15-7375-2022, https://doi.org/10.5194/amt-15-7375-2022, 2022
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Flight testing in icing conditions requires instruments that are able to accurately measure the liquid water content of supercooled large droplets (SLDs). This work finds that the 12 mm cone of the Nevzorov hot-wire probe has excellent collection properties for SLDs. We also derive a correction to compensate for the low collision efficiency of small droplets with the cone. The results provide a procedure to evaluate LWC measurements of the 12 mm cone during wind tunnel and airborne experiments.
Florin N. Isenrich, Nadia Shardt, Michael Rösch, Julia Nette, Stavros Stavrakis, Claudia Marcolli, Zamin A. Kanji, Andrew J. deMello, and Ulrike Lohmann
Atmos. Meas. Tech., 15, 5367–5381, https://doi.org/10.5194/amt-15-5367-2022, https://doi.org/10.5194/amt-15-5367-2022, 2022
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Ice nucleation in the atmosphere influences cloud properties and lifetimes. Microfluidic instruments have recently been used to investigate ice nucleation, but these instruments are typically made out of a polymer that contributes to droplet instability over extended timescales and relatively high temperature uncertainty. To address these drawbacks, we develop and validate a new microfluidic instrument that uses fluoropolymer tubing to extend droplet stability and improve temperature accuracy.
Jesse C. Anderson, Subin Thomas, Prasanth Prabhakaran, Raymond A. Shaw, and Will Cantrell
Atmos. Meas. Tech., 14, 5473–5485, https://doi.org/10.5194/amt-14-5473-2021, https://doi.org/10.5194/amt-14-5473-2021, 2021
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Fluctuations due to turbulence in Earth's atmosphere can play a role in how many droplets a cloud has and, eventually, whether that cloud rains or evaporates. We study such processes in Michigan Tech's cloud chamber. Here, we characterize the turbulent and large-scale motions of air in the chamber, measuring the spatial and temporal distributions of temperature and water vapor, which we can combine to get the distribution of relative humidity, which governs cloud formation and dissipation.
Benjamin Lang, Wolfgang Breitfuss, Simon Schweighart, Philipp Breitegger, Hugo Pervier, Andreas Tramposch, Andreas Klug, Wolfgang Hassler, and Alexander Bergmann
Atmos. Meas. Tech., 14, 2477–2500, https://doi.org/10.5194/amt-14-2477-2021, https://doi.org/10.5194/amt-14-2477-2021, 2021
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This work describes the design, calibration, and application of a hygrometer and sampling system, which have been developed and used for water content measurement in experimentally simulated atmospheric icing conditions with relevance in fundamental icing research as well as aviation testing and certification. Together with a general description of water content measurement and accompanying uncertainties, the results of a comparison to reference instruments in an icing wind tunnel are presented.
André Welti, Kimmo Korhonen, Pasi Miettinen, Ana A. Piedehierro, Yrjö Viisanen, Annele Virtanen, and Ari Laaksonen
Atmos. Meas. Tech., 13, 7059–7067, https://doi.org/10.5194/amt-13-7059-2020, https://doi.org/10.5194/amt-13-7059-2020, 2020
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We describe a modification of the SPectrometer for Ice Nuclei (SPIN) chamber to study ice nucleation at low temperatures, relevant for ice formation in cirrus clouds. Validation experiments of homogeneous freezing of aqueous ammonium sulfate droplets and heterogeneous ice nucleation on silver iodide particles are included to demonstrate the advantages of the modified SPIN chamber for the investigation of ice nucleation in the extended temperature range.
Dennis Niedermeier, Jens Voigtländer, Silvio Schmalfuß, Daniel Busch, Jörg Schumacher, Raymond A. Shaw, and Frank Stratmann
Atmos. Meas. Tech., 13, 2015–2033, https://doi.org/10.5194/amt-13-2015-2020, https://doi.org/10.5194/amt-13-2015-2020, 2020
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In this paper, we present the new moist-air wind tunnel LACIS-T (Turbulent Leipzig Aerosol Cloud Interaction Simulator). It is used to study cloud physical processes in general and interactions between turbulence and cloud microphysical processes in particular. The operating principle of LACIS-T is explained, and the first results are depicted from deliquescence and droplet formation experiments observing clear indications on the effect of turbulence on these microphysical processes.
Brian D. Swanson and Jon Nelson
Atmos. Meas. Tech., 12, 6143–6152, https://doi.org/10.5194/amt-12-6143-2019, https://doi.org/10.5194/amt-12-6143-2019, 2019
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We have built a triple-capillary cryostat designed to reduce potential instrumental effects that may have influenced earlier measurements and to improve our understanding of the processes responsible for ice crystal shapes and sizes. In this cryostat, a crystal forms on one of three well-separated and ultrafine capillaries. In this paper we describe the new instrument and present several observations made using the instrument to illustrate the instrument's advantages.
Fabian Mahrt, Jörg Wieder, Remo Dietlicher, Helen R. Smith, Chris Stopford, and Zamin A. Kanji
Atmos. Meas. Tech., 12, 3183–3208, https://doi.org/10.5194/amt-12-3183-2019, https://doi.org/10.5194/amt-12-3183-2019, 2019
Short summary
Short summary
A new instrument, the High Speed Particle Phase Discriminator (PPD-HS), is presented, with the goal of quantifying liquid and ice fraction in conditions relevant for mixed-phase clouds. PPD-HS captures the near-forward spatial intensity distribution of scattered light on a single particle basis. Symmetry analysis of the scattering pattern is used to determine the shape of the particles, with cloud droplets and ice crystals producing symmetrical and asymmetrical scattering patterns, respectively.
Sarvesh Garimella, Thomas Bjerring Kristensen, Karolina Ignatius, Andre Welti, Jens Voigtländer, Gourihar R. Kulkarni, Frank Sagan, Gregory Lee Kok, James Dorsey, Leonid Nichman, Daniel Alexander Rothenberg, Michael Rösch, Amélie Catharina Ruth Kirchgäßner, Russell Ladkin, Heike Wex, Theodore W. Wilson, Luis Antonio Ladino, Jon P. D. Abbatt, Olaf Stetzer, Ulrike Lohmann, Frank Stratmann, and Daniel James Cziczo
Atmos. Meas. Tech., 9, 2781–2795, https://doi.org/10.5194/amt-9-2781-2016, https://doi.org/10.5194/amt-9-2781-2016, 2016
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The SPectrometer for Ice Nuclei (SPIN) is a commercially available ice nuclei counter manufactured by Droplet Measurement Technologies in Boulder, CO. This study characterizes the SPIN chamber, reporting data from laboratory measurements and quantifying uncertainties. Overall, we report that the SPIN is able to reproduce previous CFDC ice nucleation measurements.
C. Budke and T. Koop
Atmos. Meas. Tech., 8, 689–703, https://doi.org/10.5194/amt-8-689-2015, https://doi.org/10.5194/amt-8-689-2015, 2015
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A new optical freezing array for the study of heterogeneous ice nucleation in microliter-sized droplets is introduced, tested and applied to the study of immersion freezing in aqueous Snomax suspensions. Using different cooling rates, a small time dependence of ice nucleation induced by two different classes of ice nucleators was detected and the corresponding heterogeneous ice nucleation rate coefficient was quantified.
N. Hoffmann, A. Kiselev, D. Rzesanke, D. Duft, and T. Leisner
Atmos. Meas. Tech., 6, 2373–2382, https://doi.org/10.5194/amt-6-2373-2013, https://doi.org/10.5194/amt-6-2373-2013, 2013
T. Clauss, A. Kiselev, S. Hartmann, S. Augustin, S. Pfeifer, D. Niedermeier, H. Wex, and F. Stratmann
Atmos. Meas. Tech., 6, 1041–1052, https://doi.org/10.5194/amt-6-1041-2013, https://doi.org/10.5194/amt-6-1041-2013, 2013
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Short summary
Optical particle spectrometers (OPSs) are a class of instruments (commonly used for measurement of particle size distributions) that require calibration. Conventionally, this is performed using a known aerosol source, which has reliability issues. In this paper, we present a technique for OPS calibration which involves placing objects in the instrument that generate a known response. This fibre calibration method was more reliable than a conventional calibration.
Optical particle spectrometers (OPSs) are a class of instruments (commonly used for measurement...
