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  - 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 17 ice nucleation measurement techniques
T2  - Atmospheric chemistry and physics
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. 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 IN 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 dry-dispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing data set 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 9 orders of magnitude in ns.
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 ns. In addition, we show evidence that the immersion freezing efficiency expressed in ns 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 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. 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, the ice nucleation activity expressed in ns was smaller for the average of the wet suspended samples and higher for the average of the dry-dispersed aerosol samples between about −27 and −18 °C. Only instruments making measurements with wet suspended samples were able to measure ice nucleation above −18 °C. A possible explanation for the deviation between −27 and −18 °C is discussed. Multiple exponential distribution fits in both linear and log space for both specific surface area-based ns(T) and geometric surface area-based ns(T) are provided. These new fits, constrained by using identical reference samples, will help to compare IN measurement methods that are not included in the present study and IN data from future IN instruments.
Y1  - 2015
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/37254
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-372542
SN  - 1680-7324
N1  - © Author(s) 2015. This work is distributed under the Creative Commons Attribution 3.0 License.
VL  - 15
SP  - 2489
EP  - 2518
PB  - European Geosciences Union
CY  - Katlenburg-Lindau
ER  -