Compositional and Mineralogical Effects on Ice Nucleation Activity of Volcanic Ash

Genareau, Kimberly; Cloer, S.; Primm, Katherine M.; Tolbert, Margaret A.; Woods, T.

doi:10.3390/atmos9070238

Cited by 11 publications

(19 citation statements)

References 66 publications

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“…The mechanisms leading to ice nucleation by fine ash are complex and not well understood [64][65][66][67][68]. Mineral composition appears also to be an important factor [69,70].…”

Section: Volcanic Icementioning

confidence: 99%

Passive Earth Observations of Volcanic Clouds in the Atmosphere

Prata

Lynch

2019

Atmosphere

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Current Earth Observation (EO) satellites provide excellent spatial, temporal and spectral coverage for passive measurements of atmospheric volcanic emissions. Of particular value for ash detection and quantification are the geostationary satellites that now carry multispectral imagers. These instruments have multiple spectral channels spanning the visible to infrared (IR) wavelengths and provide 1 × 1 km2 to 4 × 4 km2 resolution data every 5–15 min, continuously. For ash detection, two channels situated near 11 and 12 μ m are needed; for ash quantification a third or fourth channel also in the infrared is useful for constraining the height of the ash cloud. This work describes passive EO infrared measurements and techniques to determine volcanic cloud properties and includes examples using current methods with an emphasis on the main difficulties and ways to overcome them. A challenging aspect of using satellite data is to design algorithms that make use of the spectral, temporal (especially for geostationary sensors) and spatial information. The hyperspectral sensor AIRS is used to identify specific molecules from their spectral signatures (e.g., for SO2) and retrievals are demonstrated as global, regional and hemispheric maps of AIRS column SO2. This kind of information is not available on all sensors, but by combining temporal, spatial and broadband multi-spectral information from polar and geo sensors (e.g., MODIS and SEVIRI) useful insights can be made. For example, repeat coverage of a particular area using geostationary data can reveal temporal behaviour of broadband channels indicative of eruptive activity. In many instances, identifying the nature of a pixel (clear, cloud, ash etc.) is the major challenge. Sophisticated cloud detection schemes have been developed that utilise statistical measures, physical models and temporal variation to classify pixels. The state of the art on cloud detection is good, but improvements are always needed. An IR-based multispectral cloud identification scheme is described and some examples shown. The scheme is physically based but has deficiencies that can be improved during the daytime by including information from the visible channels. Physical retrieval schemes applied to ash detected pixels suffer from a lack of knowledge of some basic microphysical and optical parameters needed to run the retrieval models. In particular, there is a lack of accurate spectral refractive index information for ash particles. The size distribution of fine ash (1–63 μ m, diameter) is poorly constrained and more measurements are needed, particularly for ash that is airborne. Height measurements are also lacking and a satellite-based stereoscopic height retrieval is used to illustrate the value of this information for aviation. The importance of water in volcanic clouds is discussed here and the separation of ice-rich and ash-rich portions of volcanic clouds is analysed for the first time. More work is required in trying to identify ice-coated ash particles, and it is suggested that a class of ice-rich volcanic cloud be recognized and termed a ‘volcanic ice’ cloud. Such clouds are frequently observed in tropical eruptions of great vertical extent (e.g., 8 km or higher) and are often not identified correctly by traditional IR methods (e.g., reverse absorption). Finally, the global, hemispheric and regional sampling of EO satellites is demonstrated for a few eruptions where the ash and SO 2 dispersed over large distances (1000s km).

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“…The mechanisms leading to ice nucleation by fine ash are complex and not well understood [64][65][66][67][68]. Mineral composition appears also to be an important factor [69,70].…”

Section: Volcanic Icementioning

confidence: 99%

Passive Earth Observations of Volcanic Clouds in the Atmosphere

Prata

Lynch

2019

Atmosphere

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“…VA can act as INP depending on temperature and relative humidity conditions of the atmosphere. Previous studies on the ice nucleation properties of VA particles obtained from different sources under both mixed‐phase and cirrus cloud conditions have reported broadly different results (Durant et al., 2008; Fornea et al., 2009; Genareau et al., 2018; Gibbs et al., 2015; Hoyle et al., 2011; Jahn et al., 2019; Kulkarni et al., 2015; Mangan et al., 2017; Maters et al., 2019; Schill et al., 2015; Steinke et al., 2011). These studies have clearly established that VA particles can nucleate ice in the immersion freezing mode.…”

Section: Introductionmentioning

confidence: 95%

“…For example, Genareau et al. (2018) studied five VA samples and found that the most ice active VA sample had a high K 2 O and a low MnO content. Mangan et al.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Chemical and Mineral Compositions on the Parameterization of Immersion Freezing by Volcanic Ash Particles

et al. 2021

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Volcanic ash (VA) from explosive eruptions contributes to aerosol loadings in the atmosphere. Aside from the negative impact of VA on air quality and aviation, these particles can alter the optical and microphysical properties of clouds by triggering ice formation, thereby influencing precipitation and climate. Depending on the volcano and eruption style, VA displays a wide range of different physical, chemical, and mineralogical properties. Here, we present a unique data set on the ice nucleation activity of 15 VA samples obtained from different volcanoes worldwide. The ice nucleation activities of these samples were studied in the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud simulation chamber as well as with the Ice Nucleation Spectrometer of the Karlsruhe Institute of Technology (INSEKT). All VA particles nucleated ice in the immersion freezing mode from 263 to 238K with ice nucleation active site (INAS) densities ranging from ∼105 to 1011 m−2, respectively. The variabilities observed among the VA samples, at any given temperature, range over 3.5 orders of magnitude. The ice‐nucleating abilities of VA samples correlate to varying degrees with their bulk pyroxene and plagioclase contents as a function of temperature. We combined our new data set with existing literature data to develop an improved ice nucleation parameterization for natural VA in the immersion freezing mode. This should be useful for modeling the impact of VA on clouds.

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“…Similar factors might influence ice nucleation by volcanic ash (Kulkarni et al, 2015;Schill et al, 2015;Genareau et al, 2018).…”

mentioning

confidence: 99%

The importance of crystalline phases in ice nucleation by volcanic ash

Maters¹,

Dingwell²,

Cimarelli³

et al. 2019

Preprint

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<p><strong>Abstract.</strong> Volcanic ash is known to nucleate ice when immersed in supercooled water droplets. This process may impact the properties and dynamics of the eruption plume and cloud, as well as those of meteorological clouds once the ash is dispersed in the atmosphere. However, knowledge of what controls the ice-nucleating effectiveness (INE) of ash remains limited, although it has been suggested that crystalline components in ash may play an important role. Here we adopted a novel approach using nine pairs of tephra and their remelted and quenched glass equivalents to investigate the influence of chemical composition, crystallinity and mineralogy on ash INE in the immersion mode. For all nine pairs studied, the crystal-bearing tephra nucleated ice at higher temperatures than the corresponding crystal-free glass, demonstrating that crystalline phases are key to ash INE. Similar to findings for desert dust from arid and semi-arid regions, the presence of feldspar minerals characterises the four most ice-active tephra samples, although a high INE is observed even in the absence of alkali feldspar in samples bearing plagioclase feldspar and orthopyroxene. There is evidence of a potential indirect relationship between chemical composition and ash INE, whereby a magma of felsic to intermediate composition may generate ash containing ice-active feldspar minerals. This complex interplay between chemical composition, crystallinity, and mineralogy could help partly to explain the variability in volcanic ash INE reported in the literature. Overall, by categorically demonstrating the importance of crystalline phases in the INE of volcanic ash, our study contributes insights essential for better appraising the role of airborne ash in ice formation. Among these is the inference that glass-dominated ash emitted by the largest explosive eruptions may be less effective at impacting ice-nucleating particle populations than crystalline ash generated by smaller, more frequent eruptions.</p>

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Compositional and Mineralogical Effects on Ice Nucleation Activity of Volcanic Ash

Cited by 11 publications

References 66 publications

Passive Earth Observations of Volcanic Clouds in the Atmosphere

Passive Earth Observations of Volcanic Clouds in the Atmosphere

The Influence of Chemical and Mineral Compositions on the Parameterization of Immersion Freezing by Volcanic Ash Particles

The importance of crystalline phases in ice nucleation by volcanic ash

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