A global three-dimensional model of the tropospheric sulfur cycle

Langner, Joakim; Rodhe, Henning

doi:10.1007/bf00058134

Cited by 493 publications

(224 citation statements)

References 105 publications

Supporting

Mentioning

213

Contrasting

Unclassified

Order By: Relevance

“…The flux and mean SO 2 observations from the lowest legs (<50 m, n=61) of PASE result in an average v dep just under 0.4 cm s −1 for 10 m winds ranging from 4.5 to 10 ms −1 . Standard modeling approaches tend to assign somewhat larger v dep over the ocean between 0.5 and 1.1 cm s −1 (Langner and Rodhe 1991;Pham et al 1995;Yvon et al 1996;Karl et al 2007). …”

Section: Dry Depositionmentioning

confidence: 99%

Sulfur dioxide in the tropical marine boundary layer: dry deposition and heterogeneous oxidation observed during the Pacific Atmospheric Sulfur Experiment

et al. 2009

View full text Add to dashboard Cite

Research flights with the National Center for Atmospheric Research (NCAR) C-130 airborne laboratory were conducted over the equatorial ocean during the Pacific Atmospheric Sulfur Experiment (PASE). The focused, repetitive flight plans provided a unique opportunity to explore the principal pathways of sulfur processing in remote marine environments in close detail. Fast airborne measurements of SO 2 using the Drexel University APIMS (Atmospheric Pressure Ionization Mass Spectrometer) instrument further provided unprecedented insight into the complete budget of this important sulfur gas. In general, turbulent mixing in the marine boundary layer (MBL) continuously depletes SO 2 due to the shallow convection of the tropical trade wind regime by venting the gas into the buffer layer (BuL) above. However, on nearly one-third of the flights a net import of SO 2 into the MBL from the BuL was observed. Concurrent measurements of the DMS budget allowed for a heterogeneous S(IV) oxidation rate to be inferred from the SO 2 budget residual. The average heterogeneous loss rate was found to be 0.05 h −1 , which taken in conjunction with the observed aerosol surface area distributions and O 3 levels indicates that the supermicron aerosols maintain a near neutral pH. The average dry deposition velocity of SO 2 was found to be 0.4 cm s −1 , about 30% lower than predicted by standard parameterizations. The yield of SO 2 from DMS oxidation was found to be near unity. The mission averages indicate that approximately 57% of the SO 2 in the MBL is lost to aerosols, 27% is subject to dry deposition, 7% is mixed into the BuL, and 10% is oxidized by OH.

show abstract

Section: Dry Depositionmentioning

confidence: 99%

Sulfur dioxide in the tropical marine boundary layer: dry deposition and heterogeneous oxidation observed during the Pacific Atmospheric Sulfur Experiment

et al. 2009

View full text Add to dashboard Cite

show abstract

“…3.4). We used the heterogeneous reaction rates as calculated by Dentener and Crutzen (1993) (based on Langner and Rodhe (1991)) that were derived based on climatological monthly mean values for all meteorological parameters (e.g. relative humidity), a reaction probability of γ =0.1, and taking gas phase diffusion limitations into account.…”

Section: Model Description and Source Scenariosmentioning

confidence: 99%

Impact of reactive bromine chemistry in the troposphere

et al. 2004

View full text Add to dashboard Cite

Abstract.Recently several field campaigns and satellite observations have found strong indications for the presence of bromine oxide (BrO) in the free troposphere. Using a global atmospheric chemistry transport model we show that BrO mixing ratios of a few tenths to 2 pmol mol −1 lead to a reduction in the zonal mean O 3 mixing ratio of up to 18% in widespread areas and regionally up to 40% compared to a model run without bromine chemistry. A lower limit approach for the marine boundary layer, that does not explicitly include the release of halogens from sea salt aerosol, shows that for dimethyl sulfide (DMS) the effect is even larger, with up to 60% reduction of its tropospheric column. This is accompanied by dramatic changes in DMS oxidation pathways, reducing its cooling effect on climate. In addition there are changes in the HO 2 : OH ratio that also affect NO x and PAN. These results imply that potentially significant strong sinks for O 3 and DMS have so far been ignored in many studies of the chemistry of the troposphere.

show abstract

“…The spatial autocorrelation distance was likewise rather short, 400 to 1700 km. This situation is very different from the rather smooth temporal and spatial patterns that are depicted in modeling studies based on monthly average meteorological fields (e.g., Langner and Rodhe, 1991), which have served as the basis for evaluations of the anthropogenic indirect influence, as discussed below. The highly variable nature of the aerosol loading has implications regarding such evaluations in 14 view of the nonlinear relation between aerosol loading and the indirect forcing.…”

Section: Observational Studiesmentioning

confidence: 79%

Enhanced Shortwave Cloud Radiative Forcing Due To Anthropogenic Aerosols

Schwartz

Slingo

1996

Clouds, Chemistry and Climate

View full text Add to dashboard Cite

Berkshire RG12 2SY C K It has been suggested,, originally by Twomey (SCEP, 1970), that anthropogenic aerosols in the troposphere can influence the microphysical properties of clouds and in turn their reflectivity (albedo), thereby exerting a radiative influence on climate. This chapter presents the theoretical basis for of this so-called indirect forcing and reviews pertinent observational evidence and climate model calculations of its magnitude and geographical distribution. We restrict consideration to liquid-water clouds, in part because these clouds are the principal clouds thought to be influenced by anthropogenic aerosols, and in part because the processes responsible for nucleation of ice clouds are not sufficiently well understood to permit much to be said about any anthropogenic influence. The argument for anthropogenic influence on cloud albedo rests on the premise that aerosol particle number concentrations are substantially increased by industrial emissions. As a consequence, the number concentration of cloud droplets Ned, which is determined by the number concentration of aerosol particles in the precloud air, is also increased. This in turn leads to an enhanced multiple scattering of light within clouds isnd to an increase in the optical depth and albedo of the cloud. In contrast the physical thickness, liquid water content, and liquid water path of the cloud, which are governed to close approximation by large-scale thermodynamics, are considered to be unchanged oir at least not greatly influenced by the increase in cloud droplet concentration. There is evidence that this assumption may not be entirely correct. In particular there is indication that the decrease in drop size may inhibit precipitation development, increasing cloud liquid water content and cloud lifetime, both of which effects would contribute 1 further to reflection of solar radiation by clouds; this phenomenon is also considered here.The present chapter reviews the theory of the indirect forcing phenomenon and estimates of its magnitude, field measurements addressing aspects of this phenomenon, and approaches to describing this phenomenon in climate models. This review is necessarily fairly selective. For more extended accounts see Hobbs (1993), Andreae (1995), andHeintzenberg (1995). THEORETICAL BASIS OF INDIRECT FORCINGAerosol influences on cloud albedo and shortwave forcing. The theoretical basis for a dependence of cloud albedo on cloud droplet number density, and in turn on the number density of the aerosol particles on which cloud droplets form, is outlined by Twomey (1974Twomey ( , 1977a. To relate cloud albedo to optical depth and thus to microphysical properties we employ an analytical expression obtained from the two-stream approximation for the reflectance (albedo) RCT of a nonabsorbing, horizontally homogeneous cloud (e.g., Bohren, 1987): Here g is the asymmetry parameter for single scattering (mean cosine of the scattering angle), approximately 0.85 for cloud droplets of radius much greater than the wavelength of visib...

show abstract

A global three-dimensional model of the tropospheric sulfur cycle

Cited by 493 publications

References 105 publications

Sulfur dioxide in the tropical marine boundary layer: dry deposition and heterogeneous oxidation observed during the Pacific Atmospheric Sulfur Experiment

Sulfur dioxide in the tropical marine boundary layer: dry deposition and heterogeneous oxidation observed during the Pacific Atmospheric Sulfur Experiment

Impact of reactive bromine chemistry in the troposphere

Enhanced Shortwave Cloud Radiative Forcing Due To Anthropogenic Aerosols

Contact Info

Product

Resources

About