Perspectives on the Future of Ice Nucleation Research: Research Needs and Unanswered Questions Identified from Two International Workshops

Coluzza, Ivan; Creamean, Jessie M.; Rossi, Michel J.; Wex, Heike; Alpert, Peter A.; Bianco, Valentino; Boose, Yvonne; Dellago, Christoph; Felgitsch, Laura; Fröhlich-Nowoisky, Janine; Herrmann, Hartmut; Jungblut, Swetlana; Kanji, Zamin A.; Menzl, Georg; Moffett, Bruce F.; Moritz, Clemens; Mutzel, Anke; Pöschl, Ulrich; Schauperl, Michael; Scheel, Jan Frederik; Stopelli, Emiliano; Stratmann, Frank; Grothe, Hinrich; Schmale, David G.

doi:10.3390/atmos8080138

Cited by 74 publications

(78 citation statements)

References 231 publications

(312 reference statements)

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“…Much remains unknown about the behaviour and impact of ice nucleating particles in the atmosphere (Carslaw et al 2017;Coluzza et al 2017) and we know almost nothing about these particles in the tropics (Yakobi-Hancock et al 2014). Methods now permit a much more detailed assessment of bacterial communities and their activities (Hill et al 2014;Failor et al 2017).…”

Section: Ice Formationmentioning

confidence: 99%

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Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Sheil

2018

For. Ecosyst.

139

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Theory and evidence indicate that trees and other vegetation influence the atmospheric water-cycle in various ways. These influences are more important, more complex, and more poorly characterised than is widely realised. While there is little doubt that changes in tree cover will impact the water-cycle, the wider consequences remain difficult to predict as the underlying relationships and processes remain poorly characterised. Nonetheless, as forests are vulnerable to human activities, these linked aspects of the water-cycle are also at risk and the potential consequences of large scale forest loss are severe. Here, for non-specialist readers, I review our knowledge of the links between vegetation-cover and climate with a focus on forests and rain (precipitation). I highlight advances, uncertainties and research opportunities. There are significant shortcomings in our understanding of the atmospheric hydrological cycle and of its representation in climate models. A better understanding of the role of vegetation and tree-cover will reduce some of these shortcomings. I outline and illustrate various research themes where these advances may be found. These themes include the biology of evaporation, aerosols and atmospheric motion, as well as the processes that determine monsoons and diurnal precipitation cycles. A novel theory-the 'biotic pump'-suggests that evaporation and condensation can exert a major influence over atmospheric dynamics. This theory explains how high rainfall can be maintained within those continental land-masses that are sufficiently forested. Feedbacks within many of these processes can result in non-linear behaviours and the potential for dramatic changes as a result of forest loss (or gain): for example, switching from a wet to a dry local climate (or visa-versa). Much remains unknown and multiple research disciplines are needed to address this: forest scientists and other biologists have a major role to play. New ideas, methods and data offer opportunities to improve understanding. Expect surprises.

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Section: Ice Formationmentioning

confidence: 99%

“…For example, observations in France indicate that atmospheric acidification reduces their influence (Pouzet et al 2017). Nonetheless evidence that human activities have impacted ice nucleating particles or their properties remains too limited to generalise (Carslaw et al 2017;Coluzza et al 2017). …”

Section: Anthropogenic Impactsmentioning

confidence: 99%

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Sheil

2018

For. Ecosyst.

139

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“…INPs nucleate ice through pathways dependent upon temperature, saturation with respect to ice, and the INP type (Hoose and Möhler, J. M. Creamean et al: HOVERCAT 2012). The modes of heterogeneous ice nucleation include (1) condensation freezing, whereby ice is formed concurrently with the initial formation of liquid on CCN at supercooled temperatures; (2) immersion freezing, whereby an INP is immersed in an aqueous solution or water droplet via activation of CCN during liquid cloud formation; (3) contact freezing, whereby an INP approaches the air-water interface of a droplet (e.g., via a collision) and initiates freezing; (4) deposition nucleation, whereby ice is formed from supersaturated vapor with respect to ice (RH i > 100 %) on an INP directly; and (5) pore condensation and freezing, whereby water vapor is condensed into voids and cavities followed by glaciation (Coluzza et al, 2017;Cziczo et al, 2017;Hoose and Möhler, 2012;Kanji et al, 2017;Marcolli, 2014;Vali et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, PBAPs are relatively rare in the atmosphere, but can form ice as warm as −1 • C (Despres et al, 2012;Schnell and Vali, 1976;Vali et al, 1976;Vali and Schnell, 1975). However, constraining aerosol-cloud impacts in models ranging from the cloud-resolving to climate scales, specifically when parameterizing INPs, remains a significant challenge due to limited observations (Coluzza et al, 2017;Cziczo et al, 2017;DeMott et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

HOVERCAT: a novel aerial system for evaluation of aerosol–cloud interactions

et al. 2018

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Abstract. Aerosols have a profound impact on cloud microphysics through their ability to serve as ice nucleating particles (INPs). As a result, cloud radiative properties and precipitation processes can be modulated by such aerosolcloud interactions. However, one of the largest uncertainties associated with atmospheric processes is the indirect effect of aerosols on clouds. The need for more advanced observations of INPs in the atmospheric vertical profile is apparent, yet most ice nucleation measurements are conducted on the ground or during infrequent and intensive airborne field campaigns. Here, we describe a novel measurement platform that is less expensive and smaller (< 5 kg) when compared to traditional aircraft and tethered balloon platforms and that can be used for evaluating two modes of ice nucleation (i.e., immersion and deposition). HOVERCAT (Honing On VERtical Cloud and Aerosol properTies) flew during a pilot study in Colorado, USA, up to 2.6 km above mean sea level (1.1 km above ground level) and consists of an aerosol module that includes an optical particle counter for size distributions (0.38-17 µm in diameter) and a new sampler that collects up to 10 filter samples for offline ice nucleation and aerosol analyses on a launched balloon platform. During the May 2017 test flight, total particle concentrations were highest closest to the ground (up to 50 cm −3 at < 50 m above ground level) and up to 2 in 10 2 particles were ice nucleation active in the immersion mode (at −23 • C). The warmest temperature immersion and deposition mode INPs (observed up to −6 and −40.4 • C, respectively) were observed closest to the ground, but overall INP concentrations did not exhibit an inverse correlation with increasing altitude. HOVERCAT is a prototype that can be further modified for other airborne platforms, including tethered balloon and unmanned aircraft systems. The versatility of HOVERCAT affords future opportunities to profile the atmospheric column for more comprehensive evaluations of aerosol-cloud interactions. Based on our test flight experiences, we provide a set of recommendations for future deployments of similar measurement systems and platforms.

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“…Several other ice nucleation chambers have been developed since then including the CFDC at Texas A&M University (TAMU) used in this study. Many enhancements have been made to ice nucleation chambers (e.g., Rogers et al, 2001;Creamean et al, 2013;DeMott et al, 2015;Prenni et al, 2013;Coluzza et al, 2017;Kanji et al, 2017), including replacement of the TAMU CFDC's standard optical detector (CLIMET, model no. CI-3100), which uses particle size to distinguish ice crystals from water droplets and aerosols, with the Cloud and Aerosol Spectrometer with POLarization (CASPOL, Droplet Measurement Technologies, Inc.).…”

Section: Introductionmentioning

confidence: 99%

Using depolarization to quantify ice nucleating particle concentrations: a new method

Zenker

Collier

et al. 2017

Atmos. Meas. Tech.

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Abstract. We have developed a new method to determine ice nucleating particle (INP) concentrations observed by the Texas A&M University continuous flow diffusion chamber (CFDC) under a wide range of operating conditions. In this study, we evaluate differences in particle optical properties detected by the Cloud and Aerosol Spectrometer with POLarization (CASPOL) to differentiate between ice crystals, droplets, and aerosols. The depolarization signal from the CASPOL instrument is used to determine the occurrence of water droplet breakthrough (WDBT) conditions in the CFDC. The standard procedure for determining INP concentration is to count all particles that have grown beyond a nominal size cutoff as ice crystals. During WDBT this procedure overestimates INP concentration, because large droplets are miscounted as ice crystals. Here we design a new analysis method based on depolarization ratio that can extend the range of operating conditions of the CFDC. The method agrees reasonably well with the traditional method under non-WDBT conditions with a mean percent error of ±32.1 %. Additionally, a comparison with the Colorado State University CFDC shows that the new analysis method can be used reliably during WDBT conditions.

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Perspectives on the Future of Ice Nucleation Research: Research Needs and Unanswered Questions Identified from Two International Workshops

Cited by 74 publications

References 231 publications

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

HOVERCAT: a novel aerial system for evaluation of aerosol–cloud interactions

Using depolarization to quantify ice nucleating particle concentrations: a new method

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