TY  - JOUR
A1  - Hiranuma, Naruki
A1  - Augustin-Bauditz, Stefanie
A1  - Bingemer, Heinz
A1  - Budke, Carsten
A1  - Curtius, Joachim
A1  - Danielczok, Anja
A1  - Diehl, Karoline
A1  - Dreischmeier, Katharina
A1  - Ebert, Martin
A1  - Frank, Fabian
A1  - Hoffmann, Nadine
A1  - Kandler, Konrad
A1  - Kiselev, Alexei
A1  - Koop, Thomas
A1  - Leisner, Thomas
A1  - Möhler, Ottmar
A1  - Nillius, Björn
A1  - Peckhaus, Andreas
A1  - Rose, Diana
A1  - Weinbruch, Stephan
A1  - Wex, Heike
A1  - Boose, Yvonne
A1  - DeMott, Paul J.
A1  - Hader, John D.
A1  - Hill, Thomas C.
A1  - Kanji, Zamin A.
A1  - Kulkarni, Gargi
A1  - Levin, Ezra J. T.
A1  - McCluskey, Christina S.
A1  - Murakami, Masataka
A1  - Murray, Benjamin J.
A1  - Niedermeier, Dennis
A1  - Petters, Markus D.
A1  - O'Sullivan, Daniel
A1  - Saito, Atsushi
A1  - Schill, Gregory P.
A1  - Tajiri, Takuya
A1  - Tolbert, Margret A.
A1  - Welti, André
A1  - Whale, Thomas F.
A1  - Wright, Timothy P.
A1  - Yamashita, Katsuya
T1  - A comprehensive laboratory study on the immersion freezing behavior of illite NX particles : a comparison of seventeen ice nucleation measurement techniques
T2  - Atmospheric chemistry and physics / Discussions
N2  - 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 (INPs). However, an inter-comparison 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 Nucleation 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 IN data as a function of particle concentration, temperature (T), cooling rate and nucleation time. Seventeen measurement methods were involved in the data inter-comparison. Experiments with seven instruments started with the test sample pre-suspended in water before cooling, while ten other instruments employed water vapor condensation onto dry-dispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing dataset was evaluated using the ice nucleation active surface-site density (ns) to develop a representative ns(T) spectrum that spans a wide temperature range (−37 °C < T < −11 °C) and covers nine orders of magnitude in ns.
Our inter-comparison results revealed a discrepancy between suspension and dry-dispersed particle measurements for this mineral dust. While the agreement was good below ~ −26 °C, the ice nucleation activity, expressed in ns, was smaller for the wet suspended samples and higher for the dry-dispersed aerosol samples between about −26 and −18 °C. Only instruments making measurement techniques with wet suspended samples were able to measure ice nucleation above −18 °C. A possible explanation for the deviation between −26 and −18 °C is discussed. In general, the seventeen immersion freezing measurement techniques deviate, within the range of about 7 °C in terms of temperature, by three orders of magnitude with respect to ns. In addition, we show evidence that the immersion freezing efficiency (i.e., ns) of illite NX particles is relatively independent on droplet size, particle mass in suspension, particle size and cooling rate during freezing. A strong temperature-dependence and weak time- and size-dependence of immersion freezing efficiency of illite-rich clay mineral particles enabled the ns parameterization solely as a function of temperature. We also characterized the ns (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. A multiple exponential distribution fit is expressed as ns(T) = exp(23.82 × exp(−exp(0.16 × (T + 17.49))) + 1.39) based on the specific surface area and ns(T) = exp(25.75 × exp(−exp(0.13 × (T + 17.17))) + 3.34) based on the geometric area (ns and T in m−2 and °C, respectively). These new fits, constrained by using an identical reference samples, will help to compare IN measurement methods that are not included in the present study and, thereby, IN data from future IN instruments.
Y1  - 2014
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/37253
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-372536
SN  - 1680-7375
SN  - 1680-7367
N1  - © Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 License.
VL  - 14
SP  - 22045
EP  - 22116
PB  - European Geosciences Union
CY  - Katlenburg-Lindau
ER  -