Contribution of pollen to atmospheric ice nuclei concentrations

Hader, John D.; Wright, Timothy P.; Petters, M. D.

doi:10.5194/acp-14-5433-2014

Cited by 94 publications

(136 citation statements)

References 59 publications

(64 reference statements)

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“…It is a mixture of minerals with a considerable share of microcline, a K feldspar with a high ice nucleation ability as demonstrated in laboratory experiments (Atkinson et al, 2013;Zolles et al, 2015;Harrison et al, 2016). Pollen is among the primary biological aerosol particles that nucleate ice (Hader et al, 2014). Its importance for precipitation on the regional scale has been suggested in a number of studies (Pöschl et al, 2010;Prenni et al, 2013;Huffman et al, 2013;Hader et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Pollen is among the primary biological aerosol particles that nucleate ice (Hader et al, 2014). Its importance for precipitation on the regional scale has been suggested in a number of studies (Pöschl et al, 2010;Prenni et al, 2013;Huffman et al, 2013;Hader et al, 2014). Birch pollen is one of the most efficient pollen species at nucleating ice as high as 264 K (Diehl et al, 2001(Diehl et al, , 2002von Blohn et al, 2005;Pummer et al, 2012Augustin et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Pummer et al (2012) have shown that macromolecules on or within pollen grains are responsible for the ice nucleation activity. These macromolecules can be extracted by suspending the pollen grains in water and may be dispersed in the atmosphere during wetting and drying cycles (Pummer et al, 2012;Hader et al, 2014) and also be transported to high altitudes. Birch pollen washing water containing macromolecules with 100-300 kDa show similar freezing temperatures to the whole pollen grains (Pummer et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Refreeze experiments with water droplets containing different types of ice nuclei interpreted by classical nucleation theory

et al. 2017

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Abstract. Homogeneous nucleation of ice in supercooled water droplets is a stochastic process. In its classical description, the growth of the ice phase requires the emergence of a critical embryo from random fluctuations of water molecules between the water bulk and ice-like clusters, which is associated with overcoming an energy barrier. For heterogeneous ice nucleation on ice-nucleating surfaces both stochastic and deterministic descriptions are in use. Deterministic (singular) descriptions are often favored because the temperature dependence of ice nucleation on a substrate usually dominates the stochastic time dependence, and the ease of representation facilitates the incorporation in climate models. Conversely, classical nucleation theory (CNT) describes heterogeneous ice nucleation as a stochastic process with a reduced energy barrier for the formation of a critical embryo in the presence of an ice-nucleating surface. The energy reduction is conveniently parameterized in terms of a contact angle α between the ice phase immersed in liquid water and the heterogeneous surface. This study investigates various ice-nucleating agents in immersion mode by subjecting them to repeated freezing cycles to elucidate and discriminate the time and temperature dependences of heterogeneous ice nucleation. Freezing rates determined from such refreeze experiments are presented for Hoggar Mountain dust, birch pollen washing water, Arizona test dust (ATD), and also nonadecanol coatings. For the analysis of the experimental data with CNT, we assumed the same active site to be always responsible for freezing. Three different CNT-based parameterizations were used to describe rate coefficients for heterogeneous ice nucleation as a function of temperature, all leading to very similar results: for Hoggar Mountain dust, ATD, and larger nonadecanol-coated water droplets, the experimentally determined increase in freezing rate with decreasing temperature is too shallow to be described properly by CNT using the contact angle α as the only fit parameter. Conversely, birch pollen washing water and small nonadecanol-coated water droplets show temperature dependencies of freezing rates steeper than predicted by all three CNT parameterizations. Good agreement of observations and calculations can be obtained when a pre-factor β is introduced to the rate coefficient as a second fit parameter. Thus, the following microphysical picture emerges: heterogeneous freezing occurs at ice-nucleating sites that need a minimum (critical) surface area to host embryos of critical size to grow into a crystal. Fits based on CNT suggest that the critical active site area is in the range of 10-50 nm 2 , with the exact value depending on sample, temperature, and CNT-based parameterization. Two fitting parameters are needed to characterize individual active sites. The contact angle α lowers the energy barrier that has to be overcome to form the critical embryo at the site compared to the homogeneous case where the critical embryo develops in the volume of water....

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Refreeze experiments with water droplets containing different types of ice nuclei interpreted by classical nucleation theory

et al. 2017

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“…Thus, the influence of the random placement of particles in the drop and agglomeration on the n s estimation for suspension measurements seems small. To support this, and Hader et al (2014) simulated the role of a statistical distribution in drops. The authors demonstrated that the random component due to drop placement seemed to be small relative to the statistical variation due to nucleation probability.…”

Section: Potential Effect Of Agglomeratesmentioning

confidence: 99%

“…Extensive experimental conditions were realized by NC State-CS Hader et al, 2014). Unique aspects of this instrument are the sampling of drops within a squalene oil matrix that allows for experiments using cooling rates as slow as 0.01 K min −1 and an automated freeze detection algorithm that allows for the rapid processing of more than 1000 possible drops per experiment to improve sample statistics.…”

Section: Nc State-csmentioning

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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Revisiting ice nucleation from precipitation samples

Petters

Wright

2015

Geophys. Res. Lett.

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An emerging and unsolved question is the sensitivity of cloud processes, precipitation, and climate to the atmospheric ice nucleus spectrum. This work revisits estimation of atmospheric ice‐nucleating particle concentration derived from cloud water and precipitation samples representing a wide range of geographical locations, seasons, storm systems, precipitation types, instruments, concentrations, and temperatures. Concentrations of ice‐nucleating particles are shown to vary over 10 orders of magnitude. High variability is observed in the −5°C to −12°C range which is suggested to be biologically derived nuclei whose life cycle is associated with intermittent source and efficient sink processes. The highest ever observed nucleus concentrations at −8°C are 3 orders of magnitude lower than observed ice crystal concentrations in tropical cumuli at the same temperature. The observed upper and lower limits of the nucleus spectrum provide a possible constraint on minimum enhancement factors for secondary ice formation processes.

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Contribution of pollen to atmospheric ice nuclei concentrations

Cited by 94 publications

References 59 publications

Refreeze experiments with water droplets containing different types of ice nuclei interpreted by classical nucleation theory

Refreeze experiments with water droplets containing different types of ice nuclei interpreted by classical nucleation theory

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

Revisiting ice nucleation from precipitation samples

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