Application of linear polarized light for the discrimination of frozen and liquid droplets in ice nucleation experiments

Clauß, T.; Kiselev, Alexei; Hartmann, S.; Augustin, S.; Pfeifer, Sascha; Niedermeier, D.; Wex, Heike; Stratmann, Frank

doi:10.5194/amt-6-1041-2013

Cited by 24 publications

(19 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These droplets can subsequently freeze, depending on the nature of the immersed aerosol particle and the adjusted temperature. At the LACIS outlet, a self-built optical particle spectrometer (TOPS-Ice, Clauss et al, 2013) determines if the arriving hydrometeors are liquid droplets or frozen ice crystals, resulting in the determination of a frozen fraction, f ice .…”

Section: A5 Lacismentioning

confidence: 99%

Intercomparing different devices for the investigation of ice nucleating particles using Snomax<sup>®</sup> as test substance

Wex

Augustin-Bauditz

Boose³

et al. 2015

Atmos. Chem. Phys.

Self Cite

133

177

View full text Add to dashboard Cite

Abstract. Seven different instruments and measurement methods were used to examine the immersion freezing of bacterial ice nuclei from Snomax ® (hereafter Snomax), a product containing ice-active protein complexes from nonviable Pseudomonas syringae bacteria. The experimental conditions were kept as similar as possible for the different measurements. Of the participating instruments, some examined droplets which had been made from suspensions directly, and the others examined droplets activated on previously generated Snomax particles, with particle diameters of mostly a few hundred nanometers and up to a few micrometers in some cases. Data were obtained in the temperature range from −2 to −38 • C, and it was found that all ice-active protein complexes were already activated above −12 • C. Droplets with different Snomax mass concentrations covering 10 orders of magnitude were examined. Some instruments had very short ice nucleation times down to below 1 s, while others had comparably slow cooling rates around 1 K min −1 . Displaying data from the different instruments in terms of numbers of ice-active protein complexes per dry mass of Snomax, n m , showed that within their uncertainty, the data agree well with each other as well as to previously reported literature results. Two parameterizations were taken from literature for a direct comparison to our results, and these were a time-dependent approach based on a contact angle distribution (Niedermeier et al., 2014) and a modification of the parameterization presented in Hartmann et al. (2013) representing a time-independent approach. The agreement between these and the measured data were good; i.e., they agreed within a temperature range of 0.6 K or equivalently a range in n m of a factor of 2. From the results presented herein, we propose that Snomax, at least when carefully shared and prepared, is a suitable material to test and compare different instruments for their accuracy of measuring immersion freezing.

show abstract

Section: A5 Lacismentioning

confidence: 99%

Intercomparing different devices for the investigation of ice nucleating particles using Snomax<sup>®</sup> as test substance

Wex

Augustin-Bauditz

Boose³

et al. 2015

Atmos. Chem. Phys.

Self Cite

133

177

View full text Add to dashboard Cite

show abstract

“…At the LACIS outlet the ratio of frozen droplets to the total droplet number is determined after a residence time of 1.6 s at the coldest adjusted temperature. The experimental FF is derived from measurements with the Thermo-stabilized Optical Particle Spectrometer for the detection of ice (TOPS-Ice; Clauss et al, 2013). TOPS-Ice is installed underneath LACIS and it evaluates a change in depolarization in order to distinguish between frozen and unfrozen droplets.…”

Section: Lacismentioning

confidence: 99%

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

et al. 2017

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…A detailed analysis of thermodynamic profiles in LACIS can be found in Hartmann et al (2011). At the LACIS outlet, a self-built optical particle spectrometer (TOPS-Ice; Clauss et al, 2013) determines if the arriving hydrometeors are liquid droplets or frozen ice crystals, resulting in the determination of a frozen fraction, f ice , i.e., the number of frozen droplets divided by the total number of liquid and frozen droplets.…”

Section: H Wex Et Al: Kaolinite Particles As Ice Nucleimentioning

confidence: 99%

Kaolinite particles as ice nuclei: learning from the use of different kaolinite samples and different coatings

et al. 2014

Self Cite

View full text Add to dashboard Cite

Abstract. Kaolinite particles from two different sources (Fluka and Clay Minerals Society (CMS)) were examined with respect to their ability to act as ice nuclei (IN). This was done in the water-subsaturated regime where often deposition ice nucleation is assumed to occur, and for watersupersaturated conditions, i.e., in the immersion freezing mode. Measurements were done using a flow tube (the Leipzig Aerosol Cloud Interaction Simulator, LACIS) and a continuous-flow diffusion chamber (CFDC). Pure and coated particles were used, with coating thicknesses of a few nanometers or less, where the coating consisted of levoglucosan, succinic acid or sulfuric acid. In general, it was found that the coatings strongly reduced deposition ice nucleation. Remaining ice formation in the water-subsaturated regime could be attributed to immersion freezing, with particles immersed in concentrated solutions formed by the coatings.In the immersion freezing mode, ice nucleation rate coefficients j het from both instruments agreed well with each other, particularly when the residence times in the instruments were accounted for. Fluka kaolinite particles coated with either levoglucosan or succinic acid showed the same IN activity as pure Fluka kaolinite particles; i.e., it can be assumed that these two types of coating did not alter the ice-active surface chemically, and that the coatings were diluted enough in the droplets that were formed prior to the ice nucleation, so that freezing point depression was negligible. However, Fluka kaolinite particles, which were either coated with pure sulfuric acid or were first coated with the acid and then exposed to additional water vapor, both showed a reduced ability to nucleate ice compared to the pure particles. For the CMS kaolinite particles, the ability to nucleate ice in the immersion freezing mode was similar for all examined particles, i.e., for the pure ones and the ones with the different types of coating. Moreover, j het derived for the CMS kaolinite particles was comparable to j het derived for Fluka kaolinite particles coated with sulfuric acid. This is suggestive for the Fluka kaolinite possessing a type of ice-nucleating surface feature which is not present on the CMS kaolinite, and which can be destroyed by reaction with sulfuric acid. This might be potassium feldspar.

show abstract

Application of linear polarized light for the discrimination of frozen and liquid droplets in ice nucleation experiments

Cited by 24 publications

References 37 publications

Intercomparing different devices for the investigation of ice nucleating particles using Snomax<sup>®</sup> as test substance

Intercomparing different devices for the investigation of ice nucleating particles using Snomax<sup>®</sup> as test substance

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

Kaolinite particles as ice nuclei: learning from the use of different kaolinite samples and different coatings

Contact Info

Product

Resources

About

Application of linear polarized light for the discrimination of frozen and liquid droplets in ice nucleation experiments

Cited by 24 publications

References 37 publications

Intercomparing different devices for the investigation of ice nucleating particles using Snomax&lt;sup&gt;®&lt;/sup&gt; as test substance

Intercomparing different devices for the investigation of ice nucleating particles using Snomax&lt;sup&gt;®&lt;/sup&gt; as test substance

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

Kaolinite particles as ice nuclei: learning from the use of different kaolinite samples and different coatings

Contact Info

Product

Resources

About

Intercomparing different devices for the investigation of ice nucleating particles using Snomax<sup>®</sup> as test substance

Intercomparing different devices for the investigation of ice nucleating particles using Snomax<sup>®</sup> as test substance