Atmospheric particles acting as Ice Forming Nuclei in different size ranges

Santachiara, Gianni; Matteo, L. Di; Prodi, F.; Belosi, Franco

doi:10.1016/j.atmosres.2009.08.004

Cited by 50 publications

(39 citation statements)

References 26 publications

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“…We therefore cannot assess contributions to IN concentrations from the small number concentrations of particles with diameters >1.6 μm present in typical ambient aerosol. The failure to sample the largest particles in the present dataset is a potentially important limitation at the warmest temperatures where errors of a factor of 2 are possible at −15°C based on the size dependence of IN number concentrations measured at the Earth's surface in a recent study (34). At higher (cloud) altitudes, where large aerosol concentrations are lower, a previous study suggests that supermicron particles contribute more than 50% to total IN number concentrations at warmer than −12°C (23).…”

Section: Methodsmentioning

confidence: 99%

Predicting global atmospheric ice nuclei distributions and their impacts on climate

DeMott

Prenni²,

Liu³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

1,128

1,218

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Knowledge of cloud and precipitation formation processes remains incomplete, yet global precipitation is predominantly produced by clouds containing the ice phase. Ice first forms in clouds warmer than −36°C on particles termed ice nuclei. We combine observations from field studies over a 14-year period, from a variety of locations around the globe, to show that the concentrations of ice nuclei active in mixed-phase cloud conditions can be related to temperature and the number concentrations of particles larger than 0.5 μm in diameter. This new relationship reduces unexplained variability in ice nuclei concentrations at a given temperature from ∼10 3 to less than a factor of 10, with the remaining variability apparently due to variations in aerosol chemical composition or other factors. When implemented in a global climate model, the new parameterization strongly alters cloud liquid and ice water distributions compared to the simple, temperature-only parameterizations currently widely used. The revised treatment indicates a global net cloud radiative forcing increase of ∼1 W m −2 for each order of magnitude increase in ice nuclei concentrations, demonstrating the strong sensitivity of climate simulations to assumptions regarding the initiation of cloud glaciation.aerosol indirect effects | climate forcing | ice nucleation T he formation of ice in clouds is of vital importance to life on Earth, as ice formation is one of the key processes initiating precipitation. In addition, since ice nucleation is tied to the action of specific aerosol particles, natural and human impacts on ice nucleation in the atmosphere can lead to alteration of the energy and hydrological cycles (1). Ice nucleation in clouds occurs via two primary pathways: homogeneous freezing of liquid particles below about −36°C and heterogeneous ice nucleation, triggered by "ice nuclei" that possess surface properties favorable to lowering the energy barrier to crystallization. Once ice is formed, some circumstances may favor generation of ice from preexisting ice particles, or secondary ice formation (2). Heterogeneous ice nucleation remains an enigmatic topic involving multiple mechanistic processes (3) that sometimes defy ready investigation or description. Despite the lack of a complete understanding of heterogeneous ice formation processes, a variety of techniques have been developed and used to detect the presence of and quantify the number concentrations of atmospheric ice nuclei as a function of temperature (4). These measurements show that, although generally representing only 1 in 10 5 of ambient particles in the free troposphere (5), ice nuclei (IN) can nevertheless exert an influence on cold cloud microphysical processes that is disproportionate to their low number concentrations. For example, the concentrations of IN needed to explain observed precipitation rates range from as small as 10 −3 per standard liter at −10°C (6) to more typical estimates of a few IN per standard liter at −20°C (7).The sensitivity of precipitation initiation fro...

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Section: Methodsmentioning

confidence: 99%

Predicting global atmospheric ice nuclei distributions and their impacts on climate

DeMott

Prenni²,

Liu³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

1,128

1,218

View full text Add to dashboard Cite

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“…Although it is still in use today, the method was more widely applied during the 1970s (e.g. Bigg, 1973;Hobbs and Atkinson, 1976;Schnell and Delany, 1976;Bowdle et al, 1985;Rosinski and Morgan, 1991;Santachiara et al, 2010).…”

Section: Motivationmentioning

confidence: 99%

Atmospheric ice nucleators active ≥ −12 °C can be quantified on PM<sub>10</sub> filters

Conen

Henne

Morris³

et al. 2012

Atmos. Meas. Tech.

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Abstract. Small number concentrations render it difficult to quantify ice nucleators (IN) in the atmosphere active at warm temperatures. A useful new method for IN measurement based around filter collections is proposed. It makes use of quartz filters used in 24 h PM 10 monitoring (720 m 3 air sample). Small subsamples (1.8 mm diameter) from the effective filter area and from the clean fringe (blank) are subjected to immersion freezing tests. We applied the method to eight filters from the High Alpine Research Station Jungfraujoch (3580 m above sea level) in the Swiss Alps. All filters carried IN active at −7 • C and below. Number concentrations of IN active at −8, −10, and −12 • C were on average 3.3, 10.7, and 17.2 m −3 , respectively. Several-fold larger numbers of IN active at ≥ −12 • C per unit mass of PM 10 were found in air masses influenced by Swiss and southern German atmospheric boundary layer air, compared to a Saharan dust event. In combination with data on PM 10 mass, the method may be used to re-construct time series of IN number concentrations.

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“…Although nearly 50 yr have elapsed since the beginning of the study of ice nuclei, still no agreement has been reached as to the most appropriate technique to quantify the IN concentration (Santachiara et al, 2010). The role of supersaturation in the activation of the IN has been identified as the main factor producing the divergence among the results of IN quantification using different techniques.…”

Section: Introductionmentioning

confidence: 99%

“…Different methods involve the drawing of large samples of air through a membrane filter that retain ice nuclei or collect aerosols (e.g. Santachiara et al, 2010). This technique allows estimate the IN concentration by counting the ice crystals that develop upon the exposure of the substrate to freezing temperatures and supersaturation.…”

Section: Introductionmentioning

confidence: 99%

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Measurements of natural deposition ice nuclei in Córdoba, Argentina

López

Ávila

2013

Atmos. Chem. Phys.

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Ice nucleation in the atmosphere is of practical and fundamental importance since ice crystals influence the release of snow, rain and hail. Suspended aerosols in the atmosphere typically initiate freezing at temperatures below −15 °C; although occasionally freezing occurs at higher temperatures. In this work we describe an experimental device designed to measure the concentration of natural ice nuclei under controlled temperature and supersaturation conditions. The measurements were performed at Córdoba City, for temperatures between −15 °C and −30 °C and the sampled air was supersaturated with respect to ice and subsaturated with respect to liquid water; under these conditions the deposition ice nuclei were quantified. There are few studies reported in the literature regarding measurements of deposition ice nuclei concentration and, to our knowledge, there are no previous laboratory data of this kind of ice nuclei for T < −20 °C. The results show that the number of deposition ice nuclei increases at colder temperatures and higher supersaturations. These results are in general in good agreement with results previously reported by other authors. A fitting function which depends on temperature and supersaturation is proposed to parameterize the results obtained in the present work

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Atmospheric particles acting as Ice Forming Nuclei in different size ranges

Cited by 50 publications

References 26 publications

Predicting global atmospheric ice nuclei distributions and their impacts on climate

Predicting global atmospheric ice nuclei distributions and their impacts on climate

Atmospheric ice nucleators active ≥ −12 °C can be quantified on PM<sub>10</sub> filters

Measurements of natural deposition ice nuclei in Córdoba, Argentina

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Atmospheric particles acting as Ice Forming Nuclei in different size ranges

Cited by 50 publications

References 26 publications

Predicting global atmospheric ice nuclei distributions and their impacts on climate

Predicting global atmospheric ice nuclei distributions and their impacts on climate

Atmospheric ice nucleators active ≥ −12 °C can be quantified on PM&lt;sub&gt;10&lt;/sub&gt; filters

Measurements of natural deposition ice nuclei in Córdoba, Argentina

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Product

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Atmospheric ice nucleators active ≥ −12 °C can be quantified on PM<sub>10</sub> filters