Aerosol-cloud-precipitation effects over Germany as simulated by a convective-scale numerical weather prediction model

Seifert, Axel; Köhler, Carmen; Beheng, K.D.

doi:10.5194/acp-12-709-2012

Cited by 126 publications

(153 citation statements)

References 55 publications

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“…However, in most 3-D model simulations (Khain et al, 2005;Seifert and Beheng, 2006;Tao et al, 2007;Seifert et al, 2012) the sensitivity of the aerosol concentration on the evolution of clouds was studied in the range between N CN = 100 cm −3 and N CN = 3200 cm −3 , assuming a model salt that is like the very hydrophilic sodium chloride (κ = 1.28). This is very unrealistic for pyroconvective clouds, because during a biomass-burning event a high number of less hydrophilic particles (κ < 0.6) are emitted.…”

Section: Summary and Discussionmentioning

confidence: 99%

3-D model simulations of dynamical and microphysical interactions in pyroconvective clouds under idealized conditions

et al. 2014

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Abstract. Dynamical and microphysical processes in pyroconvective clouds in mid-latitude conditions are investigated using idealized three-dimensional simulations with the Active Tracer High resolution Atmospheric Model (ATHAM). A state-of-the-art two-moment microphysical scheme building upon a realistic parameterization of cloud condensation nuclei (CCN) activation has been implemented in order to study the influence of aerosol concentration on cloud development. The results show that aerosol concentration influences the formation of precipitation. For low aerosol concentrations (N CN = 200 cm −3 ), rain droplets are rapidly formed by autoconversion of cloud droplets. This also triggers the formation of large graupel and hail particles, resulting in an early onset of precipitation. With increasing aerosol concentration (N CN = 1000 cm −3 and N CN = 20 000 cm −3 ) the formation of rain droplets is delayed due to more but smaller cloud droplets. Therefore, the formation of ice crystals and snowflakes becomes more important for the eventual formation of graupel and hail, which is delayed at higher aerosol concentrations. This results in a delay of the onset of precipitation and a reduction of its intensity with increasing aerosol concentration. This study is the first detailed investigation of the interaction between cloud microphysics and the dynamics of a pyroconvective cloud using the combination of a high-resolution atmospheric model and a detailed microphysical scheme.

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Section: Summary and Discussionmentioning

confidence: 99%

3-D model simulations of dynamical and microphysical interactions in pyroconvective clouds under idealized conditions

et al. 2014

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“…Two primary responses have emerged: (i) S o decreases monotonically with increasing L [Wood et al, 2009;Terai et al, 2012] and (ii) S o increases with L, reaches a maximum, and decreases thereafter [Feingold and Siebert, 2009;Sorooshian et al, 2009;Jiang et al, 2010]. (S o analysis has also been applied to mixed phase clouds but the behavior is more complex [Seifert et al, 2012] and is not addressed here.) The response of S o to L has important implications for the potential for aerosol to modify precipitation rates and, in the case of climate models, for their representation of the lifetime of liquid cloud condensate.…”

Section: Introductionmentioning

confidence: 99%

On the relationship between cloud contact time and precipitation susceptibility to aerosol

et al. 2013

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[1] The extent to which the rain rate from shallow, liquid-phase clouds is microphysically influenced by aerosol, and therefore drop concentration N d perturbations, is addressed through analysis of the precipitation susceptibility, S o . Previously published work, based on both models and observations, disagrees on the qualitative behavior of S o with respect to variables such as liquid water path L or the ratio between accretion and autoconversion rates. Two primary responses have emerged: (i) S o decreases monotonically with increasing L and (ii) S o increases with L, reaches a maximum, and decreases thereafter. Here we use a variety of modeling frameworks ranging from box models of (size-resolved) collision-coalescence, to trajectory ensembles based on large eddy simulation to explore the role of time available for collision-coalescence t c in determining the S o response. The analysis shows that an increase in t c shifts the balance of rain production from autoconversion (a N d -dependent process) to accretion (roughly independent of N d ), all else (e.g., L) equal. Thus, with increasing cloud contact time, warm rain production becomes progressively less sensitive to aerosol, all else equal. When the time available for collision-coalescence is a limiting factor, S o increases with increasing L whereas when there is ample time available, S o decreases with increasing L. The analysis therefore explains the differences between extant studies in terms of an important precipitation-controlling parameter, namely the integrated liquid water history over the course of an air parcel's contact with a cloud.

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“…Seifert et al (2012) investigated the influence of substantially perturbing C ccn from 100 to 3200 cm −3 (see above for a brief discussion of this paper). Accordingly, the grid-scale explicit nucleation rate is calculated from the time derivative of the activation relation (Seifert and Beheng, 2006):…”

Section: The Cosmo-muscat Model and Revised Cloud Activationmentioning

confidence: 99%

“…Further, some groups previously implemented aerosol-cloud interactions in COSMO, albeit with a different aerosol scheme (Bangert et al, 2011;Zubler et al, 2011;Possner et al, 2015) and very few are coupled to the radiation scheme. Seifert et al (2012) compared the operational one-moment microphysics scheme to a two-moment scheme. They found that aerosol perturbation has a significant effect on radiation and near-surface temperature, rather than the resulting surface precipitation.…”

Section: Introductionmentioning

confidence: 99%

“…Also, Lim and Hong (2010) have included a prognostic equation for cloud water and cloud condensation nuclei number concentration (C ccn ), which could reduce the uncertainty in investigating the aerosol effect on cloud properties and the precipitation process in the WRF model. Seifert et al (2012) and Weverberg et al (2014) compared the operational one-moment and two-moment microphysical schemes in the Consortium for Small-Scale Modeling atmospheric model (COSMO). Further, some groups previously implemented aerosol-cloud interactions in COSMO, albeit with a different aerosol scheme (Bangert et al, 2011;Zubler et al, 2011;Possner et al, 2015) and very few are coupled to the radiation scheme.…”

Section: Introductionmentioning

confidence: 99%

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Implementation of aerosol–cloud interactions in the regional atmosphere–aerosol model COSMO-MUSCAT(5.0) and evaluation using satellite data

et al. 2017

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Abstract. The regional atmospheric model Consortium for Small-scale Modeling (COSMO) coupled to the Multi-Scale Chemistry Aerosol Transport model (MUSCAT) is extended in this work to represent aerosol-cloud interactions. Previously, only one-way interactions (scavenging of aerosol and in-cloud chemistry) and aerosol-radiation interactions were included in this model. The new version allows for a microphysical aerosol effect on clouds. For this, we use the optional two-moment cloud microphysical scheme in COSMO and the online-computed aerosol information for cloud condensation nuclei concentrations (C ccn ), replacing the constant C ccn profile. In the radiation scheme, we have implemented a droplet-size-dependent cloud optical depth, allowing now for aerosol-cloud-radiation interactions. To evaluate the models with satellite data, the Cloud Feedback Model Intercomparison Project Observation Simulator Package (COSP) has been implemented. A case study has been carried out to understand the effects of the modifications, where the modified modeling system is applied over the European domain with a horizontal resolution of 0.25 • × 0.25 • . To reduce the complexity in aerosol-cloud interactions, only warm-phase clouds are considered. We found that the online-coupled aerosol introduces significant changes for some cloud microphysical properties. The cloud effective radius shows an increase of 9.5 %, and the cloud droplet number concentration is reduced by 21.5 %.

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Aerosol-cloud-precipitation effects over Germany as simulated by a convective-scale numerical weather prediction model

Cited by 126 publications

References 55 publications

3-D model simulations of dynamical and microphysical interactions in pyroconvective clouds under idealized conditions

3-D model simulations of dynamical and microphysical interactions in pyroconvective clouds under idealized conditions

On the relationship between cloud contact time and precipitation susceptibility to aerosol

Implementation of aerosol–cloud interactions in the regional atmosphere–aerosol model COSMO-MUSCAT(5.0) and evaluation using satellite data

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