Small Ice Particles in Tropospheric Clouds: Fact or Artifact? Airborne Icing Instrumentation Evaluation Experiment

Korolev, Alexei; Emery, Edward; Strapp, J. W.; Cober, Stewart G.; Isaac, George A.; Wasey, M. A.; Marcotte, Dave

doi:10.1175/2010bams3141.1

Cited by 284 publications

(336 citation statements)

References 14 publications

(2 reference statements)

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“…Issues with CIP-100 data acquisition during the Constrain project meant that no actual images were recorded and only the real-time generated PSD was saved. Large particle shattering could not therefore be diagnosed, but this is not expected to affect the PSD above 500 µm (Korolev et al, 2011). In addition, the CIP-100 is principally used here to show that there are few large particles above the maximum of the other 2D probes.…”

Section: Instrumentationmentioning

confidence: 99%

“…Lastly, shattering of ice particles occurs during mechanical impact with probe housings ahead of the sample volume. The shattered fragments are small but the number entering the sample volume may exceed a few hundred (Korolev et al, 2011). To mitigate shattering, the tips of the probe arms were modified following the design of Korolev et al (2011).…”

Section: Instrumentationmentioning

confidence: 99%

“…The shattered fragments are small but the number entering the sample volume may exceed a few hundred (Korolev et al, 2011). To mitigate shattering, the tips of the probe arms were modified following the design of Korolev et al (2011). The modified tips deflect shattered particles away from the sample volume.…”

Section: Instrumentationmentioning

confidence: 99%

“…The sample area of the CIP-100 is over one order of magnitude greater than the 2D-C, which improves the counting statistics of large ice particles. The CIP-100 probe arms have also been modified following the design of Korolev et al (2011) to mitigate the effect of ice-particle shattering. Issues with CIP-100 data acquisition during the Constrain project meant that no actual images were recorded and only the real-time generated PSD was saved.…”

Section: Instrumentationmentioning

confidence: 99%

See 3 more Smart Citations

The effective density of small ice particles obtained from in situ aircraft observations of mid‐latitude cirrus

Cotton

Field

Ulanowski

et al. 2012

Quart J Royal Meteoro Soc

157

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The effective ice-particle density, parametrized through a mass-dimension relation, is widely used in ice microphysical schemes for weather and climate models. In this study, we use aircraft-based observations in mid-latitude cirrus taken during the Constrain field programme in 2010. The low temperatures and a humidity often close to ice saturation meant that the typical ice particles observed were small (maximum dimension 20-800 µm) and ice water contents were low (0.001-0.05 g m −3 ). Two new instruments are included in this study: the Small Ice Detector Mark-2 (SID-2) and the deep-cone Nevzorov Total Water Content probe. SID-2 is a new singleparticle light-scattering instrument and was used to identify and size small ice particles (10-150 µm). The deep-cone Nevzorov probe is shown to be able to collect small ice masses with sufficient sensitivity. The focus of this article is on the effective density of small ice particles (both pristine ice crystals and small aggregates up to 600 µm maximum dimension). Due to instrument limitations in previous studies, the effective density of small ice particles is questionable.Aircraft flights in six cirrus cases provided ice-particle measurements throughout the depth of the cirrus. The particle size distribution (PSD) was mostly bimodal. The smaller ice-crystal mode dominated the PSD near cloud top and the larger ice-aggregate mode dominated near cloud base. A mass-dimension relation valid for both ice crystals and aggregates was found that provided a best fit to the observations. For small ice particles (less than 70 µm diameter) the density is constant (700 kg m −3 ), while for larger ice crystals or aggregates the mass-dimension relation is m(D) = 0.0257D 2.0 . These measurements allow testing of the diagnostic split between ice crystals and aggregates used in the Met Office Unified Model.

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Section: Instrumentationmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

See 2 more Smart Citations

The effective density of small ice particles obtained from in situ aircraft observations of mid‐latitude cirrus

Cotton

Field

Ulanowski

et al. 2012

Quart J Royal Meteoro Soc

157

View full text Add to dashboard Cite

show abstract

“…The importance of small ice crystals (< 50 µm) for cirrus cloud radiative properties is a matter of controversial debate, mainly because some measurements seemed to clearly overestimate the number concentrations of small ice particles due to particle shattering on the instrument inlets (Field et al, 2006;McFarquhar et al, 2007;Jensen et al, 2009;Lawson, 2011;Korolev et al, 2011). Yet, if present, small ice crystals are important for the radiative properties of these clouds (Garrett et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Influence of particle size and shape on the backscattering linear depolarisation ratio of small ice crystals – cloud chamber measurements in the context of contrail and cirrus microphysics

et al. 2012

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Abstract. The article presents the laser scattering and depolarisation instrument SIMONE that is installed at the large aerosol and cloud chamber facility AIDA of the Karlsruhe Institute of Technology. SIMONE uses a 488 nm cw laser to probe simulated atmospheric clouds by measuring the scattered light from the 1.8 • and 178.2 • directions. At 178.2 • , the scattered light is analysed for the linear polarisation state to deduce the particle linear depolarisation ratio δ p which is a common measurement parameter of atmospheric lidar applications. The optical setup and the mathematical formalism of the depolarisation detection concept are given. SIMONE depolarisation measurements in spheroidal hematite aerosol and supercooled liquid clouds are used to validate the instrument.SIMONE data from a series of AIDA ice nucleation experiments at temperatures between 195 and 225 K were analysed in terms of the impact of the ice particle microphysics on δ p . We found strong depolarisation values of up to 0.4 in case of small growing and sublimating ice particles with volume equivalent diameters of only a few micrometers.Modelling runs with the T-matrix method showed that the measured depolarisation ratios can be accurately reproduced assuming spheroidal and cylindrical particles with a size distribution that has been constrained by IR extinction spectroscopy. Based on the T-matrix modelling runs, we demonstrate that in case of small ice crystals the SIMONE depolarisation results are representative for the lidar depolarisation ratio which is measured at exact backscattering direction of 180 • .The relevance of our results for the interpretation of recent lidar observations in cirrus and contrails is discussed. In view of our results, the high depolarisation ratios observed by the spaceborne lidar CALIOP in the tropical upper troposphere might be a hint for the presence of small (sublimating) ice particles in the outflows of deep convective systems.

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Observational quantification of the separation of simple and complex atmospheric ice particles

Schmitt

Heymsfield

2014

Geophysical Research Letters

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The impact of ice clouds on weather and climate is a function of ice particle shape through light scattering properties and cloud lifetime through ice particle sedimentation rates. Many weather forecast and climate models use two categories to represent ice cloud particles: cloud ice and snow, though the distinction between particle categories is generally without observational justification. Improved characterization of cloud ice and snow as well as the transition between them will make models more realistic. An analysis of particle imagery data from high-resolution aircraft particle imaging probes indicates that atmospheric ice particles can easily be separated by particle complexity. In this work, a technique is described which enables the clear separation of vapor grown particles from aggregates of particles. When applied to two example data sets, the technique shows that the separation between these categories occurs at 150 and 250 microns, for two example data sets.

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Small Ice Particles in Tropospheric Clouds: Fact or Artifact? Airborne Icing Instrumentation Evaluation Experiment

Abstract: No abstract available.

Cited by 284 publications

References 14 publications

The effective density of small ice particles obtained from in situ aircraft observations of mid‐latitude cirrus

The effective density of small ice particles obtained from in situ aircraft observations of mid‐latitude cirrus

Influence of particle size and shape on the backscattering linear depolarisation ratio of small ice crystals – cloud chamber measurements in the context of contrail and cirrus microphysics

Observational quantification of the separation of simple and complex atmospheric ice particles

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