Development of a continuous flow thermal gradient diffusion chamber for ice nucleation studies

1988 ◽  
Vol 22 (2) ◽  
pp. 149-181 ◽  
Author(s):  
David C. Rogers
Keyword(s):  
Continuous Flow ◽  
Thermal Gradient ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Gradient Diffusion

scholarly journals Technical note: Characterization of a static thermal-gradient CCN counter

2006 ◽  
Vol 6 (2) ◽  
pp. 2151-2174 ◽  
Author(s):  
G. P. Frank ◽  
U. Dusek ◽  
M. O. Andreae
Keyword(s):  
Water Vapor ◽  
Thermal Gradient ◽  
Cloud Condensation Nuclei ◽  
Diffusion Chamber ◽  
Calibration Method ◽  
Theoretical Description ◽  
Technical Note ◽  
Number Concentration ◽  
Gradient Diffusion

Abstract. The static (parallel-plate thermal-gradient) diffusion chamber (SDC) was one of the first instruments designed to measure cloud condensation nuclei (CCN) concentrations as a function of supersaturation. It has probably also been the most widely used type of CCN counter. This paper describes the detailed experimental characterization of a SDC CCN counter, including calibration with respect to supersaturation and particle number concentration. In addition, we investigated the proposed effect of lowered supersaturation because of water vapor depletion with increasing particle concentration. The results obtained gives a larger understanding why and in which way it is necessary to calibrate the SDC CCN counter. The calibration method is described in detail as well. The method can, in parts, be used for calibrations also for other types of CCN counters. We conclude the following: 1) it is important to experimentally calibrate SDC CCN counters with respect to supersaturation, and not only base the supersaturation on the theoretical description of the instrument; 2) the number concentration calibration needs to be performed as a function of supersaturation, also for SDC CCN counter using the photographic technique; and 3) we observed no evidence that water vapor depletion lowered the supersaturation.

scholarly journals Results from the University of Toronto continuous flow diffusion chamber (UT-CFDC) at the international workshop for comparing ice nucleation measuring systems (ICIS 2007)

2010 ◽  
Vol 10 (9) ◽  
pp. 20857-20886 ◽  
Author(s):  
Z. A. Kanji ◽  
P. J. DeMott ◽  
O. Möhler ◽  
J. P. D. Abbatt
Keyword(s):  
Continuous Flow ◽  
International Workshop ◽  
Measurement Techniques ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Ice Formation ◽  
Aerosol Sample ◽  
Measuring Systems ◽  
University Of Toronto ◽  
The University

Abstract. The University of Toronto continuous flow diffusion chamber (UT-CFDC) was used to study heterogeneous ice nucleation at the International Workshop on Comparing Ice Nucleation Measuring Systems (ICIS 2007) which also represented the 4th ice nucleation workshop, on 14–28 September 2007. One goal of the workshop was to inter-compare different ice nucleation measurement techniques using the same aerosol sample source and preparation method. The aerosol samples included four types of desert mineral dust, graphite soot particles, and live and dead bacterial cells (Snomax®). This paper focuses on the UT-CFDC results, with a comparison to techniques of established heritage including the Colorado State CFDC and the AIDA expansion chamber. Good agreement was found between the different instruments with a few specific differences attributed to the variation in how onset of ice formation is defined between the instruments. It was found that when efficiency of ice formation is based on the lowest onset relative humidity, Snomax® particles were most efficient followed by the desert dusts and then soot. For all aerosols, deposition mode freezing was only observed for T < 245 K except for the dead bacteria where freezing occurred below water saturation as warm as 263 K.

scholarly journals Comparing contact and immersion freezing from continuous flow diffusion chambers

2016 ◽  
Author(s):  
Baban Nagare ◽  
Claudia Marcolli ◽  
André Welti ◽  
Olaf Stetzer ◽  
Ulrike Lohmann
Keyword(s):  
Residence Time ◽  
Continuous Flow ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Freezing Process ◽  
Electrical Mobility ◽  
Cloud Droplets ◽  
Immersion Freezing ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Abstract. Ice nucleating particles (INPs) in the atmosphere are responsible for glaciating cloud droplets between 237 K and 273 K. Different mechanisms of heterogeneous ice nucleation can compete under mixed-phase cloud conditions. Contact freezing is considered relevant because higher ice nucleation temperatures than for immersion freezing for the same INPs were observed. It has limitations because its efficiency depends on the number of collisions between cloud droplets and INPs. This study compares immersion and contact freezing efficiencies of three different INPs. The contact freezing data was obtained with the ETH CoLlision Ice Nucleation CHamber (CLINCH) using 80 μm diameter droplets which can interact with INPs for residence times of 2 s and 4 s in the chamber. The contact freezing efficiency was calculated by estimating the number of collisions between droplets and particles. Theoretical formulations of collision efficiencies gave too high freezing efficiencies for all investigated INPs, namely AgI particles with 200 nm electrical mobility diameter, 400 and 800 nm diameter ATD and kaolinite particles. Comparison of freezing efficiencies by contact and immersion freezing is therefore limited by the accuracy of collision efficiencies. The concentration of particles was 1000 cm−3 for ATD and kaolinite and 500, 1000, 2000 and 5000 cm−3 for AgI. For concentrations < 5000 cm−3, the droplets collect only one particle on average during their time in the chamber. For ATD and kaolinite particles, contact freezing efficiencies at 2 s residence time were smaller than at 4 s, which is in disagreement with a collisional contact freezing process but in accordance with contact freezing insideout or immersion freezing. For best comparison with contact freezing results, immersion freezing experiments of the same INPs were performed with the continuous flow diffusion chamber IMCA/ZINC for 3 s residence time. In IMCA/ZINC, each INP is activated into a droplet in IMCA and provides its surface for ice nucleation in the ZINC chamber. The comparison of contact and immersion freezing results did not confirm a general enhancement of freezing efficiency for contact compared with immersion freezing experiments. For AgI particles the onset of heterogeneous freezing in CLINCH was even shifted to lower temperatures compared with IMCA/ZINC. For ATD, freezing efficiencies for contact and immersion freezing experiments were similar. For kaolinite particles, contact freezing became detectable at higher temperatures than immersion freezing. Using contact angle information between water and the INP, it is discussed how the position of the INP in or on the droplets may influence its ice nucleation activity.

scholarly journals Technical Note: Characterization of a static thermal-gradient CCN counter

2007 ◽  
Vol 7 (12) ◽  
pp. 3071-3080 ◽  
Author(s):  
G. P. Frank ◽  
U. Dusek ◽  
M. O. Andreae
Keyword(s):  
Water Vapor ◽  
Thermal Gradient ◽  
Cloud Condensation Nuclei ◽  
Diffusion Chamber ◽  
Calibration Method ◽  
Theoretical Description ◽  
Technical Note ◽  
Number Concentration ◽  
Gradient Diffusion

Abstract. The static (parallel-plate thermal-gradient) diffusion chamber (SDC) was one of the first instruments designed to measure cloud condensation nuclei (CCN) concentrations as a function of supersaturation. It has probably also been the most widely used type of CCN counter. This paper describes the detailed experimental characterization of a SDC CCN counter, including calibration with respect to supersaturation and particle number concentration. In addition, we investigated the proposed effect of lowered supersaturation because of water vapor depletion with increasing particle concentration. The results obtained give a better understanding why and in which way it is necessary to calibrate the SDC CCN counter. The calibration method is described in detail and can, in parts, be used for calibrations also for other types of CCN counters. We conclude the following: 1) it is important to experimentally calibrate SDC CCN counters with respect to supersaturation, and not only base the supersaturation on the theoretical description of the instrument; 2) the number concentration calibration needs to be performed as a function of supersaturation, also for SDC CCN counter using the photographic technique; and 3) we observed no evidence that water vapor depletion lowered the supersaturation.

scholarly journals A continuous flow diffusion chamber study of sea salt particles acting as cloud nuclei: deliquescence and ice nucleation

Tellus B ◽  
2018 ◽  
Vol 70 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Xiangrui Kong ◽  
Martin J. Wolf ◽  
Michael Roesch ◽  
Erik S. Thomson ◽  
Thorsten Bartels-Rausch ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Sea Salt ◽  
Chamber Study

scholarly journals A new thermal gradient ice nucleation diffusion chamber instrument: design, development and first results using Saharan mineral dust

2009 ◽  
Vol 2 (1) ◽  
pp. 153-179 ◽  
Author(s):  
G. Kulkarni ◽  
S. Dobbie ◽  
J. McQuaid
Keyword(s):  
Thermal Gradient ◽  
Mineral Dust ◽  
Aerosol Particles ◽  
Experimental System ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Experimental Investigations ◽  
Design Development ◽  
Static Mode ◽  
First Results

Abstract. A new Thermal Gradient ice nucleation Diffusion Chamber (TGDC) capable of investigating ice nucleation efficiency of atmospherically important aerosols, termed Ice Nuclei (IN), has been designed, constructed and validated. The TGDC can produce a range of supersaturations with respect to ice (SSi) over the temperature range of −10 to −34°C for sufficiently long time needed to observe the ice nucleation by the aerosol particles. The novel aspect of this new TGDC is that the chamber is run in static mode with aerosol particles supported on a Teflon substrate, which can be raised and lowered in a controlled way through the SSi profile within the chamber, and nucleation events are directly observed using digital photography. The TGDC consists of two ice coated plates to which a thermal gradient is applied to produce the range of SSi. The design of the TGDC gives the ability to understand time-related ice nucleation event information and to perform experiments at different temperatures and SSi conditions for different IN without changing the thermal gradient within the TGDC. The temperature and SSi conditions of the experimental system are validated by observing (NH4)2SO4 deliquescence and the results are in good agreement with the literature data. First results are presented of the onset ice nucleation for mineral dust sampled from the Saharan Desert, including images of nucleation and statistical distributions of onset ice nucleation SSi as a function of temperature. This paper illustrates how useful this new TGDC is for process level studies of ice nucleation and more experimental investigations are needed to better quantify the role of ice formation in the atmosphere.

scholarly journals Ice Nucleation Studies of Mineral Dust Particles with a New Continuous Flow Diffusion Chamber

2006 ◽  
Vol 40 (2) ◽  
pp. 134-143 ◽  
Author(s):  
Abdus Salam ◽  
Ulrike Lohmann ◽  
Brian Crenna ◽  
Glen Lesins ◽  
Peter Klages ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Mineral Dust ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Dust Particles

scholarly journals Results from the University of Toronto continuous flow diffusion chamber at ICIS 2007: instrument intercomparison and ice onsets for different aerosol types

2011 ◽  
Vol 11 (1) ◽  
pp. 31-41 ◽  
Author(s):  
Z. A. Kanji ◽  
P. J. DeMott ◽  
O. Möhler ◽  
J. P. D. Abbatt
Keyword(s):  
Continuous Flow ◽  
Water Saturation ◽  
International Workshop ◽  
Measurement Techniques ◽  
Diffusion Chamber ◽  
Ice Nucleation ◽  
Ice Formation ◽  
Aerosol Sample ◽  
University Of Toronto ◽  
The University

Abstract. The University of Toronto continuous flow diffusion chamber (UT-CFDC) was used to study heterogeneous ice nucleation at the International Workshop on Comparing Ice Nucleation Measuring Systems (ICIS 2007) which also represented the 4-th ice nucleation workshop, on 14–28 September 2007. One goal of the workshop was to inter-compare different ice nucleation measurement techniques using the same aerosol sample source and preparation method. The aerosol samples included four types of desert mineral dust, graphite soot particles, and live and dead bacterial cells (Snomax®). This paper focuses on the UT-CFDC results, with a comparison to techniques of established heritage including the Colorado State CFDC and the AIDA expansion chamber. Good agreement was found between the different instruments with a few specific differences, especially at low temperatures, perhaps due to the variation in how onset of ice formation is defined between the instruments and the different inherent residence times. It was found that when efficiency of ice formation is based on the lowest onset relative humidity, Snomax® particles were most efficient followed by the desert dusts and then soot. For all aerosols, deposition mode freezing was only observed for T<45 K except for the dead bacteria where freezing occurred below water saturation as warm as 263 K.

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