Simulation of the influence of aerosol particle characteristics on clouds and precipitation with LM-SPECS: Model description and first results

Grützun, Verena; Knoth, Oswald; Simmel, Martin

doi:10.1016/j.atmosres.2008.03.002

Cited by 29 publications

(26 citation statements)

References 48 publications

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“…The goal of many laboratory studies was and is to assess the ice nucleation ability of selected aerosol particles of a specific composition (e.g., Pruppacher and Saenger, 1955;Isono et al, 1959a). While earlier parameterizations of heterogeneous ice nucleation (Young, 1974;Meyers et al, 1992) did not include any aerosol-specific dependencies, the results of such experiments and their parametrical descriptions are nowadays frequently used in atmospheric models on different scales, from cloud resolving models to global climate models (e.g., Kärcher and Lohmann, 2003;Liu and Penner, 2005;Lohmann and Diehl, 2006;Grützun et al, 2008;Phillips et al, 2009;Eidhammer et al, 2010;Hoose et al, 2010a,b;Storelvmo et al, 2011), and enter the calculations of aerosol indirect effects in mixed-phase and cirrus clouds.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous ice nucleation on atmospheric aerosols: a review of results from laboratory experiments

2012

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Abstract.A small subset of the atmospheric aerosol population has the ability to induce ice formation at conditions under which ice would not form without them (heterogeneous ice nucleation). While no closed theoretical description of this process and the requirements for good ice nuclei is available, numerous studies have attempted to quantify the ice nucleation ability of different particles empirically in laboratory experiments. In this article, an overview of these results is provided. Ice nucleation "onset" conditions for various mineral dust, soot, biological, organic and ammonium sulfate particles are summarized. Typical temperaturesupersaturation regions can be identified for the "onset" of ice nucleation of these different particle types, but the various particle sizes and activated fractions reported in different studies have to be taken into account when comparing results obtained with different methodologies. When intercomparing only data obtained under the same conditions, it is found that dust mineralogy is not a consistent predictor of higher or lower ice nucleation ability. However, the broad majority of studies agrees on a reduction of deposition nucleation by various coatings on mineral dust. The ice nucleation active surface site (INAS) density is discussed as a simple and empirical normalized measure for ice nucleation activity. For most immersion and condensation freezing measurements on mineral dust, estimates of the temperature-dependent INAS density agree within about two orders of magnitude. For deposition nucleation on dust, the spread is significantly larger, but a general trend of increasing INAS densities with increasing supersaturation is found. For soot, the presently available results are divergent. Estimated average INAS densities are high for ice-nucleation active bacteria at high subzero temperatures. At the same time, it is shown that INAS densities of some other biological aerosols, like certain pollen grains, fungal spores and diatoms, tend to be similar to those of dust. These particles may owe their high ice nucleation onsets to their large sizes. Surface-area-dependent parameterizations of heterogeneous ice nucleation are discussed. For immersion freezing on mineral dust, fitted INAS densities are available, but should not be used outside the temperature interval of the data they were based on. Classical nucleation theory, if employed with only one fitted contact angle, does not reproduce the observed temperature dependence for immersion nucleation, the temperature and supersaturation dependence for deposition nucleation, and the time dependence of ice nucleation. Formulations of classical nucleation theory with distributions of contact angles offer possibilities to overcome these weaknesses.

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Section: Introductionmentioning

confidence: 99%

Heterogeneous ice nucleation on atmospheric aerosols: a review of results from laboratory experiments

2012

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“…15 The original COSMO model works with a Kessler-type cloud microphysics bulk scheme including various states of water (cloud and rain water, several forms of ice). Grützun et al (2008) completely replaced the bulk scheme by a spectral bin microphysics as described in Simmel and Wurzler (2006) and Diehl et al (2006). The time integration of the coupling scheme between the COSMO model and the bin microphysics is performed with two different time steps because the microphysics operates on much smaller time scales than the concurrent dynamical processes.…”

Section: Previous Version Of Cosmo-specsmentioning

confidence: 99%

“…In this paper an improved version of the 3D cloud modeling system COSMO-SPECS (Grützun et al, 2008) is presented which allows to study the impact of aerosol particle types and three heterogeneous freezing modes on ice formation and precipitation. A deep convective cloud with a wide temperature range from +20°C on ground level and -50°C at cloud top was simulated.…”

Section: Summary and Conclusion 15mentioning

confidence: 99%

“…Within the COSMO model the 20 horizontal and vertical winds as well as temperature and pressure are transported within a time step of 10 to 100 s leading to dynamically updated values. These are used for the microphysical loop which consists of time steps of 1 s or smaller where changes in the hydrometeor spectra due to the included microphysical processes are calculated (Grützun et al, 2008).…”

Section: Previous Version Of Cosmo-specsmentioning

confidence: 99%

“…Model simulations dealing with these issues were performed with the state-of-the-art model system COSMO-SPECS, a 3D 30 cloud model developed by Grützun et al (2008). A follow-up version which was numerically more effective was provided by Lieber et al (2012).…”

Section: Introductionmentioning

confidence: 99%

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Model simulations with COSMO-SPECS: Impact of heterogeneous freezing modes and ice nucleating particle types on ice formation and precipitation in a deep convective cloud

Diehl¹,

Grützun²

2017

Preprint

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Abstract. In deep convective clouds, heavy rain is often formed involving the ice phase as essential process. Simulations 10 were performed using the 3D cloud resolving model COSMO-SPECS with detailed spectral microphysics including parametrizations of homogeneous and three heterogeneous freezing modes. The initial conditions were selected to result in a deep convective cloud reaching 14 km altitude with strong updrafts up to 40 m/s. In such altitudes with corresponding temperatures below -40°C the major fraction of liquid drops freezes homogeneously. The goal of the present model simulations was to investigate how additional heterogeneous freezing will affect ice formation and precipitation although its 15 contribution to total ice formation may be rather low. In such a situation small perturbations which do not show significant effects at first sight may trigger cloud microphysical responses. Effects of the following small perturbations were studied: (1) additional ice formation via immersion, contact, and deposition modes in comparison to sole homogeneous freezing, (2) contact and deposition freezing in comparison to immersion freezing, (3) small fractions of biological ice nucleating particles (INP) in comparison to higher fractions of mineral dust INP. The results indicate that the modification of 20 precipitation proceeds via the formation of larger ice particles which may be supported by direct freezing of larger drops, the growth of pristine ice particles by riming, and by nucleation of larger drops by collisions with pristine ice particles. In comparison to the reference case homogeneous freezing such small perturbations may affect an enhancement of total precipitation but mostly the effects are limited to modifications of the temporal development of precipitation, i.e. a gradual increase already at early cloud stages instead a strong increase at later cloud stages. These effects are coupled with changes 25 in the local distribution of precipitation, i.e. approximately 50% more precipitation in the cloud center. The modifications depend on the active freezing modes, the fractions of active INP, and the composition of the internal mixtures in the drops.Atmos. Chem. Phys. Discuss., https://doi

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Ice nucleation properties of rust and bunt fungal spores and their transport to high altitudes, where they can cause heterogeneous freezing

et al. 2013

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[1] Rust and bunt spores that act as ice nuclei (IN) could change the formation characteristics and properties of ice-containing clouds. In addition, ice nucleation on rust and bunt spores, followed by precipitation, may be an important removal mechanism of these spores from the atmosphere. Using an optical microscope, we studied the ice nucleation properties of spores from four rust species (Puccinia graminis, Puccinia triticina, Puccinia allii, and Endocronartium harknesssii) and two bunt species (Tilletia laevis and Tilletia tritici) immersed in water droplets. We show that the cumulative number of IN per spore is 5 × 10 À3 , 0.01, and 0.10 at temperatures of roughly À24°C, À25°C, and À28°C, respectively. Using a particle dispersion model, we also investigated if these rust and bunt spores will reach high altitudes in the atmosphere where they can cause heterogeneous freezing. Simulations suggest that after 3 days and during periods of high spore production, between 6 and 9% of 15 μm particles released over agricultural regions in Kansas (U.S.), North Dakota (U.S.), Saskatchewan (Canada), and Manitoba (Canada) can reach at least 6 km in altitude. An altitude of 6 km corresponds to a temperature of roughly À25°C for the sites chosen. The combined results suggest that (a) ice nucleation by these fungal spores could play a role in the removal of these particles from the atmosphere and (b) ice nucleation by these rust and bunt spores are unlikely to compete with mineral dust on a global and annual scale at an altitude of approximately 6 km.

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Simulation of the influence of aerosol particle characteristics on clouds and precipitation with LM-SPECS: Model description and first results

Cited by 29 publications

References 48 publications

Heterogeneous ice nucleation on atmospheric aerosols: a review of results from laboratory experiments

Heterogeneous ice nucleation on atmospheric aerosols: a review of results from laboratory experiments

Model simulations with COSMO-SPECS: Impact of heterogeneous freezing modes and ice nucleating particle types on ice formation and precipitation in a deep convective cloud

Ice nucleation properties of rust and bunt fungal spores and their transport to high altitudes, where they can cause heterogeneous freezing

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