Ice Nucleating Particle Measurements at 241 K during Winter Months at 3580 m MSL in the Swiss Alps

Boose, Yvonne; Kanji, Zamin A.; Kohn, Monika; Sierau, B.; Zipori, Assaf; Crawford, Ian; Lloyd, Gary; Bukowiecki, Nicolas; Herrmann, Erik; Kupiszewski, Piotr; Steinbacher, Martin; Lohmann, Ulrike

doi:10.1175/jas-d-15-0236.1

Cited by 73 publications

(128 citation statements)

References 102 publications

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“…The uncertainty in the AF for PINC and SPIN is 14 %. experiments with PINC revealed particle losses below 5 % (Boose et al, 2016); thus, these losses do not explain the observed difference between the CFDC (PINC) and immersion freezing (PIMCA-PINC, LACIS).…”

Section: Apparent Differences Between Immersion and Condensation Freementioning

confidence: 76%

“…In many field measurements CFDCs have been used for measurements of INP concentration at water-supersaturated conditions (e.g., DeMott et al, 2010DeMott et al, , 2016Tobo et al, 2013;Boose et al, 2016;Lacher et al, 2017) and are sometimes used to represent immersion freezing (e.g., DeMott et al, 2017). As water-supersaturated conditions in CFDCs should result in droplet formation followed by freezing at a constant temperature, CFDCs should simulate condensation freezing (see, e.g., Welti et al, 2014, for a discussion of possible condensation freezing mechanisms).…”

Section: Apparent Differences Between Immersion and Condensation Freementioning

confidence: 99%

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Leipzig Ice Nucleation chamber Comparison (LINC): intercomparison of four online ice nucleation counters

et al. 2017

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Abstract. Ice crystal formation in atmospheric clouds has a strong effect on precipitation, cloud lifetime, cloud radiative properties, and thus the global energy budget. Primary ice formation above 235 K is initiated by nucleation on seed aerosol particles called ice-nucleating particles (INPs). Instruments that measure the ice-nucleating potential of aerosol particles in the atmosphere need to be able to accurately quantify ambient INP concentrations. In the last decade several instruments have been developed to investigate the icenucleating properties of aerosol particles and to measure ambient INP concentrations. Therefore, there is a need for intercomparisons to ensure instrument differences are not interpreted as scientific findings.In this study, we intercompare the results from parallel measurements using four online ice nucleation chambers. Seven different aerosol types are tested including untreated and acid-treated mineral dusts (microcline, which is a K-feldspar, and kaolinite), as well as birch pollen washing waters. Experiments exploring heterogeneous ice nucleation above and below water saturation are performed to cover the whole range of atmospherically relevant thermodynamic conditions that can be investigated with the intercompared chambers. The Leipzig Aerosol Cloud Interaction Simulator (LACIS) and the Portable Immersion Mode Cooling chAmber coupled to the Portable Ice Nucleation Chamber (PIMCA-PINC) performed measurements in the immersion freezing mode. Additionally, two continuous-flow diffusion chambers (CFDCs) PINC and the Spectrometer for Ice Nuclei (SPIN) are used to perform measurements below and just above water saturation, nominally presenting deposition nucleation and condensation freezing.The results of LACIS and PIMCA-PINC agree well over the whole range of measured frozen fractions (FFs) and temperature. In general PINC and SPIN compare well and the observed differences are explained by the ice crystal growth and different residence times in the chamber. To study the mechanisms responsible for the ice nucleation in the four instruments, the FF (from LACIS and PIMCA-PINC) and the activated fraction, AF (from PINC and SPIN), are compared. Measured FFs are on the order of a factor of 3 higher than AFs, but are not consistent for all aerosol types and temperatures investigated. It is shown that measurements from CFDCs cannot be assumed to produce the same results as those instruments exclusively measuring immersion freezing. Instead, the need to apply a scaling factor to CFDCs operating above water saturation has to be considered to allow comparison with immersion freezing devices. Our results provide further awareness of factors such as the importance of dispersion methods and the quality of particle size selection for intercomparing online INP counters.

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Section: Apparent Differences Between Immersion and Condensation Freementioning

confidence: 76%

Section: Apparent Differences Between Immersion and Condensation Freementioning

confidence: 99%

Leipzig Ice Nucleation chamber Comparison (LINC): intercomparison of four online ice nucleation counters

et al. 2017

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“…Possible mechanisms to explain the observed variability of ICNC can only be discussed briefly, because meteorological parameters were not measured. Very localized high ice nucleation rates cannot explain the observed ICNC of several tens per liter at the observed temperature of −5 • C because the average concentration of ice nucleating particles observed at the nearby Jungfraujoch did not exceed 7 stdL −1 at −32 • C (Boose et al, 2016). Ice crystals may also fall into the cloud from an ice cloud lying above, which was observed on satellite pictures.…”

Section: Mixed-phase Casementioning

confidence: 93%

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

et al. 2017

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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 10 m s −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 6.5 µm, partitions between cloud droplets and ice crystals for a size larger than 25 µm and obtains a statistically significantly size distribution for every 5 m in vertical ascent.

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“…Several studies exist from airborne platforms (e.g., Bigg, 1967;Rogers et al, 1998;Prenni et al, 2009;DeMott et al, 2010;Avramov et al, 2011;Schrod et al, 2017) and ground-based observations (e.g., DeMott et al, 2003b;Chou et al, 2011;Ardon-Dryer and Levin, 2014;Mason et al, 2016;Boose et al, 2016a, b) quantifying the number concentration of INPs and identifying their potential sources. Typically, filter sampling with subsequent offline freezing methods, and online measurements with continuous-flow-diffusion chambers (CFDCs) are used as INP measurement techniques.…”

Section: Introductionmentioning

confidence: 99%

“…However, this comes at the cost of a low temporal resolution since the sampling times of the filters often are on the order of a few hours or longer. CFDCs measure INP concentrations in real time with a higher temporal resolution, on the order of a few to tens of minutes (e.g., Rogers, 1988;Rogers et al, 2001;Chou et al, 2011), but their total sampling volume is lower, and their sensitivity to detect INPs is limited at low concentrations (Boose et al, 2016a). This in particular is challenging at low supercooling or in areas where INP concentrations are lower than 0.1-1 per standard liter (std L −1 ; normalized to standard T of 273 K and pressure, p, of 1013 hPa).…”

Section: Introductionmentioning

confidence: 99%

The Horizontal Ice Nucleation Chamber (HINC): INP measurements at conditions relevant for mixed-phase clouds at the High Altitude Research Station Jungfraujoch

Lacher¹,

Lohmann²,

Boose

et al. 2017

Atmos. Chem. Phys.

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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 the accuracy of the thermodynamic conditions of temperature (T ) and relative humidity (RH) in HINC with uncertainties in T of ± 0.4 K and in RH with respect to water (RH w ) of ±1.5 %, which translates into an uncertainty in RH with respect to ice (RH i ) 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-subsaturated conditions (RH w = 94 %), relevant for the formation of ice clouds, and in the watersupersaturated regime (RH w = 104 %) to represent ice formation occurring under mixed-phase cloud conditions. In winters 2015 and 2016 the median INP concentrations at RH w = 94 % was below the minimum detectable concentration. At RH w = 104 %, INP concentrations were an order of magnitude higher, with median concentrations in winter 2015 of 2.8 per standard liter (std L −1 ; normalized to standard T of 273 K and pressure, p, of 1013 hPa) and 4.7 std L −1 in winter 2016. The measurements are in agreement with previous winter measurements obtained with the Portable Ice Nucleation Chamber (PINC) of 2.2 std L −1 at the same location. During winter 2015, two events caused the INP concentrations at RH w = 104 % to significantly increase above the campaign average. First, an increase to 72.1 std L −1 was measured during an event influenced by marine air, arriving at the JFJ from the North Sea and the Norwegian Sea. The contribution from anthropogenic or other sources can thereby not be ruled out. Second, INP concentrations up to 146.2 std L −1 were observed during a Saharan dust event. To our knowledge this is the first time that a clear enrichment in ambient INP concentration in remote regions of the atmosphere is observed during a time of marine air mass influence, suggesting the importance of marine particles on ice nucleation in the free troposphere.

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Ice Nucleating Particle Measurements at 241 K during Winter Months at 3580 m MSL in the Swiss Alps

Cited by 73 publications

References 102 publications

Leipzig Ice Nucleation chamber Comparison (LINC): intercomparison of four online ice nucleation counters

Leipzig Ice Nucleation chamber Comparison (LINC): intercomparison of four online ice nucleation counters

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

The Horizontal Ice Nucleation Chamber (HINC): INP measurements at conditions relevant for mixed-phase clouds at the High Altitude Research Station Jungfraujoch

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