Experimental investigation of homogeneous freezing of sulphuric acid particles in the aerosol chamber AIDA

Möhler, Ottmar; Stetzer, O.; Schaefers, S.; Linke, Christian; Schnaiter, Martin; Tiede, R. L.; Saathoff, H.; Krämer, M.; Mangold, Alexander; Budz, P.; Zink, Peter; Schreiner, J.; Mauersberger, K.; Haag, Werner O.; Kärcher, B.; Schurath, U.

doi:10.5194/acp-3-211-2003

Cited by 192 publications

(239 citation statements)

References 41 publications

(50 reference statements)

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“…9a, b. Starting from near ice saturated conditions at t = 0 s, the chamber gas was adiabatically cooled from 201.6 to 194.5 K within 630 s which at first resulted in a continuous increase of the saturation ratio until the threshold for the homogeneous nucleation of ice in the H 2 SO 4 solution droplets was reached at about t = 300 s. A threshold saturation ratio for the onset of ice nucleation around 1.68 was determined which is in good agreement with the results of the homogeneous ice nucleation study by Möhler et al (2003). After the onset of ice nucleation, the saturation ratio further increased to a peak value of 1.75 at t = 330 s before the growing ice particles started to deplete the water vapour.…”

Section: Homogeneous Nucleation At T Initial = 202 K (Ice01 14)supporting

confidence: 84%

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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Section: Homogeneous Nucleation At T Initial = 202 K (Ice01 14)supporting

confidence: 84%

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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“…The development of AIDA-CECC allows the simulation of atmospherically representative cloud parcel formation and evolution (Möhler et al, 2003). Therefore, it is an advantage of CECC that the parameterization derived from its experiments can be most readily extended to atmospheric conditions (Niemand et al, 2012).…”

Section: Limitations Of Instrument Typesmentioning

confidence: 99%

A comprehensive laboratory study on the immersion freezing behavior of illite NX particles: a comparison of 17 ice nucleation measurement techniques

et al. 2015

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Abstract. Immersion freezing is the most relevant heterogeneous ice nucleation mechanism through which ice crystals are formed in mixed-phase clouds. In recent years, an increasing number of laboratory experiments utilizing a variety of instruments have examined immersion freezing activity of atmospherically relevant ice-nucleating particles. However, an intercomparison of these laboratory results is a difficult task because investigators have used different ice nucleation (IN) measurement methods to produce these results. A remaining challenge is to explore the sensitivity and accuracy of these techniques and to understand how the IN results are potentially influenced or biased by experimental parameters associated with these techniques.Within the framework of INUIT (Ice Nuclei Research Unit), we distributed an illite-rich sample (illite NX) as a representative surrogate for atmospheric mineral dust particles to investigators to perform immersion freezing experiments using different IN measurement methods and to obtain Published by Copernicus Publications on behalf of the European Geosciences Union. N. Hiranuma et al.: A comparison of 17 IN measurement techniquesIN data as a function of particle concentration, temperature (T ), cooling rate and nucleation time. A total of 17 measurement methods were involved in the data intercomparison. Experiments with seven instruments started with the test sample pre-suspended in water before cooling, while 10 other instruments employed water vapor condensation onto drydispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing data set was evaluated using the ice nucleation active surface-site density, n s , to develop a representative n s (T ) spectrum that spans a wide temperature range (−37 • C < T < −11 • C) and covers 9 orders of magnitude in n s .In general, the 17 immersion freezing measurement techniques deviate, within a range of about 8 • C in terms of temperature, by 3 orders of magnitude with respect to n s . In addition, we show evidence that the immersion freezing efficiency expressed in n s of illite NX particles is relatively independent of droplet size, particle mass in suspension, particle size and cooling rate during freezing. A strong temperature dependence and weak time and size dependence of the immersion freezing efficiency of illite-rich clay mineral particles enabled the n s parameterization solely as a function of temperature. We also characterized the n s (T ) spectra and identified a section with a steep slope between −20 and −27 • C, where a large fraction of active sites of our test dust may trigger immersion freezing. This slope was followed by a region with a gentler slope at temperatures below −27 • C. While the agreement between different instruments was reasonable below ∼ −27 • C, there seemed to be a different trend in the temperature-dependent ice nucleation activity from the suspension and dry-dispersed particle measurements for this mineral dust, in particular at higher temperatures. For instance,...

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“…Reasonable results were obtained, yielding good agreement with satellite observations of the seasonal cycle and the amount of zonal mean water vapor. However, supersaturation equivalent to 140-180 % (Möhler et al, 2003) or 120-200 % (Murray et al, 2010) in relative humidity with respect to ice (RH ice ) at a temperature of 240-180 K is reported from studies based on laboratory experiments. A value of RH ice of up to 200 % at < 200 K has been reported from studies based on aircraft measurements (Krämer et al, 2009).…”

Section: Y Inai Et Al: Water Vapor Matchmentioning

confidence: 99%

Dehydration in the tropical tropopause layer estimated from the water vapor match

et al. 2013

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We apply the match technique, whereby the same air mass is observed more than once and such cases are termed a "match", to study the dehydration process associated with horizontal advection in the tropical tropopause layer (TTL) over the western Pacific. The matches are obtained from profile data taken by the Soundings of Ozone and Water in the Equatorial Region (SOWER) campaign network observations using isentropic trajectories calculated from European Centre for Medium-Range Weather Forecasts (ECMWF) operational analyses. For the matches identified, extensive screening procedures are performed to verify the representativeness of the air parcel and the validity of the isentropic treatment, and to check for possible water injection by deep convection, consistency between the sonde data and analysis field referring to the ozone conservation. Among the matches that passed the screening tests, we identified some cases corresponding to the first quantitative value of dehydration associated with horizontal advection in the TTL. The statistical features of dehydration for the air parcels advected in the lower TTL are derived from the matches. The threshold of nucleation is estimated to be 146 ± 1% (1σ) in relative humidity with respect to ice (RH_ice), while dehydration seems to continue until RH_ice reaches about 75 ± 23% (1σ) in the altitude region from 350 to 360 K. The efficiency of dehydration expressed by the relaxation time required for the supersaturated air parcel to approach saturation is empirically determined from the matches. A relaxation time of approximately one hour reproduces the second water vapor observation reasonably well, given the first observed water vapor amount and the history of the saturation mixing ratio during advection in the lower TTL

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Experimental investigation of homogeneous freezing of sulphuric acid particles in the aerosol chamber AIDA

Cited by 192 publications

References 41 publications

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

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

A comprehensive laboratory study on the immersion freezing behavior of illite NX particles: a comparison of 17 ice nucleation measurement techniques

Dehydration in the tropical tropopause layer estimated from the water vapor match

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