Numerical study of droplet size dependent chemistry in oceanic, wintertime stratus cloud at southern mid-latitudes

Ayers, G. P.; Larson, Timothy V.

doi:10.1007/bf00053672

Cited by 54 publications

(27 citation statements)

References 37 publications

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“…The reaction rates and their temperature dependence are taken from Ayers & Larson (1990). Sources of atmospheric sulphur are dimethyl sulphide in the ocean and gaseous SO 2 from anthropogenic emissions, as well as from biomass smoke.…”

Section: An Overview Of the Microphysical Chemical Parcel Modelmentioning

confidence: 99%

Integrating biomass, sulphate and sea-salt aerosol responses into a microphysical chemical parcel model: implications for climate studies

Ghosh

Smith

Rap

2007

Phil. Trans. R. Soc. A.

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Aerosols are known to influence significantly the radiative budget of the Earth. Although the direct effect (whereby aerosols scatter and absorb solar and thermal infrared radiation) has a large perturbing influence on the radiation budget, the indirect effect (whereby aerosols modify the microphysical and hence the radiative properties and amounts of clouds) poses a greater challenge to climate modellers. This is because aerosols undergo chemical and physical changes while in the atmosphere, notably within clouds, and are removed largely by precipitation. The way in which aerosols are processed by clouds depends on the type, abundance and the mixing state of the aerosols concerned. A parametrization with sulphate and sea-salt aerosol has been successfully integrated within the Hadley Centre general circulation model (GCM). The results of this combined parametrization indicate a significantly reduced role, compared with previous estimates, for sulphate aerosol in cloud droplet nucleation and, consequently, in indirect radiative forcing. However, in this bicomponent system, the cloud droplet number concentration, N d (a crucial parameter that is used in GCMs for radiative transfer calculations), is a smoothly varying function of the sulphate aerosol loading. Apart from sea-salt and sulphate aerosol particles, biomass aerosol particles are also present widely in the troposphere. We find that biomass smoke can significantly perturb the activation and growth of both sulphate and sea-salt particles. For a fixed salt loading, N d increases linearly with modest increases in sulphate and smoke masses, but significant nonlinearities are observed at higher non-sea-salt mass loadings. This non-intuitive N d variation poses a fresh challenge to climate modellers.

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Section: An Overview Of the Microphysical Chemical Parcel Modelmentioning

confidence: 99%

Integrating biomass, sulphate and sea-salt aerosol responses into a microphysical chemical parcel model: implications for climate studies

Ghosh

Smith

Rap

2007

Phil. Trans. R. Soc. A.

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“…However, the uncertainty is significant, and our present results are not necessarily in disagreement with this finding. The importance of the initial gas-phase ammonia before cloud processing has been discussed in detail by Ayers and Larson [ 1990].…”

Section: Sievering Et Al [This Issue] Proposed That Aerosolmentioning

confidence: 99%

Heterogeneous sulfate production in the remote marine environment: Cloud processing and sea‐salt particle contributions

Gurciullo¹,

Lerner²,

Sievering³

et al. 1999

J. Geophys. Res.

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“…The set of interaction parameters used in the Pitzer scheme was more comprehensive than that used in the previous work of Chameides and Stelson [1992]. The approach follows that of Ayers and Larson [1990], simulating the macroscopic evolution of a Lagrangian parcel of moist aerosol-containing air moving through the marine boundary layer, although for the simulations reported here, the model is similarly initialized at 50 m below cloud base and only focuses on sulphate just below and in cloud.…”

Section: Introductionmentioning

confidence: 99%

Modeling heterogeneous sulphate production in maritime stratiform clouds

O’Dowd¹,

Lowe²,

Clegg³

et al. 2000

J. Geophys. Res.

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Abstract. A size-resolved droplet physico chemical model linked to a Lagrangian parcel framework was developed and used to study the heterogeneous sulphate production process in marine stratiform clouds. This model study provides a rigorous approach to cloud chemistry processing by treating the effects of non ideal chemistry on both aqueous phase equilibration and droplet growth using the Pitzer method to overcome many of the shortcomings of alternative thermodynamic methods. In addition, the current study uses a multi modal representation of seasalt aerosol, rather than the single mode used in most previous work. The results of the model simulations showed a distribution of sulphate production across the aerosol size range that was non linear and that a significant fraction (=75-90%) of the sulphate was produced in droplets formed on sea-salt aerosol particles. The number of sea-salt particles affected both the total amount of sulphate produced and the fraction produced on cloud droplets formed around non-sea-salt sulphate aerosol. Dissolved ozone and hydrogen peroxide were both important as oxidant species, although the ozone-driven oxidation pathway was dominant in droplets formed on sea-salt aerosol particles. The rate of sulphate production was found to be a non linear function of the gaseous sulphur dioxide concentration at cloud base and only very weakly dependent on sulphate nuclei concentration. A comparison of sulphate production in cloud and below cloud indicates that sulphate production in sea-salt nuclei is not limited by the carbonate buffer and that in-cloud production can exceed, many times, that of cloud-free production due to the "virtual" buffering capacity of the cloud. The use of non ideal solution effects appear important, particularly for clean-to-moderately polluted SO2 concentrations (< 500 parts per trillion) and when sea-salt nuclei are present, resulting in at least 40% lower sulphate production when compared to ideal solution simulations.

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Numerical study of droplet size dependent chemistry in oceanic, wintertime stratus cloud at southern mid-latitudes

Cited by 54 publications

References 37 publications

Integrating biomass, sulphate and sea-salt aerosol responses into a microphysical chemical parcel model: implications for climate studies

Integrating biomass, sulphate and sea-salt aerosol responses into a microphysical chemical parcel model: implications for climate studies

Heterogeneous sulfate production in the remote marine environment: Cloud processing and sea‐salt particle contributions

Modeling heterogeneous sulphate production in maritime stratiform clouds

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