I know little about electrostatics. Is it generally easier to charge droplets from a ship than an aircraft?
I suggest that some of the links between SAI and MCB as regards plume dynamics have been overlooked. Electrostatics, decompression and evaporative cooling often seem to have been given sparse consideration in some of the discussions and models considered for methods of aerosol distribution. A On 7 Feb 2015 11:35, "Stephen Salter" <[email protected]> wrote: > Hi?? All > > On 1 January 2015 I circulated to the geo-group a comment on the Stuart > coagulation paper pointing out that the words 'electrostatic' and?? > 'charge' did not appear.?? I also pointed out that coagulation will be > higher in spray with the very wide range of drop sizes assumed by Stuart > than in the mono-disperse spray which we hope to produce. > > Anand and Mayya do not mention electrostatic charge either.?? At the top > of the right column of page 754 they do mention polydispersity but only in > connection with the Stuart paper and do not say what spread of drop sizes > their model uses. > > Alan Gadian tells me that, as the sea surface stays at near constant > temperature and the night time cooling of the air above it will be > increased even further by the loss of latent heat for evaporation spray, > there will?? extreme instability at the bottom of the marine boundary > layer.?? It would be useful to know if this could be even more unstable > than class A used in section 2 of Anand and Mayya. > > I agree with the Poster's comment about wanting experimental validation > especially for a mono-disperse spray.?? However one obvious requirement is > missing. > > Stephen > > > Emeritus Professor of Engineering Design. School of Engineering. > University of Edinburgh. Mayfield Road. Edinburgh EH9 3JL. Scotland > [email protected] Tel +44 (0)131 650 5704 Cell 07795 203 195 > WWW.see.ed.ac.uk/~shs YouTube Jamie Taylor Power for Change > > > On 07/02/2015 01:14, Andrew Lockley wrote: > > Poster's note : I personally look forward to seeing thesethe plume models > experimentally validated. Lack of dispersion validation is a major issue > for MCB. > > Comment on "Reduced efficacy of marine cloud brightening geoengineering > due to in-plume aerosol coagulation: parameterization and global > implications" by Stuart et al. (2013) > S. Anand and Y. S. Mayya > > Abstract. > We examine the parameterized model of Stuart et al. (2013) vis-??-vis a > diffusion-based model proposed by us earlier (Anand and Mayya, 2011) to > estimate the fraction of aerosol particles surviving coagulation in a > dispersing plume. While the Stuart et al. approach is based on the > solutions to the coagulation problem in an expanding plume model, the > diffusion-based approach solves the diffusion???coagulation equation for a > steady-state standing plume to arrive at the survival fraction > correlations. We discuss the differences in the functional forms of the > survival fraction expressions obtained in the two approaches and compare > the results for the case studies presented in Stuart et al. (2013) > involving different particle emission rates and atmospheric stability > categories. There appears to be a better agreement between the two models > at higher survival fractions as compared to lower survival fractions; on > the whole, the two models agree with each other within a difference of 10%. > The diffusion-based expression involves a single exponent fit to a > theoretically generated similarity variable combining the parameters of the > problem with inbuilt exponents and hence avoids the multi-exponent > parameterization exercise. It also possesses a wider range of applicability > in respect of the source and atmospheric parameters as compared to that > based on parameterization. However, in the diffusion model, the choice of a > representative value for the coagulation coefficient is more prescriptive > than rigorous, which has been addressed in a more satisfactory manner by > the parameterization method. The present comparative exercise, although > limited in scope, confirms the importance of aerosol microphysical > processes envisaged by Stuart et al. for cloud brightening applications. In > a larger context, it seems to suggest that either of the two forms of > expressions might be suitable for incorporation into global-/regional-scale > air pollution models for predicting the contribution of localized sources > to the particle number loading in the atmosphere. > > Citation: > Anand, S. and Mayya, Y. S.: Comment on "Reduced efficacy of marine cloud > brightening geoengineering due to in-plume aerosol coagulation: > parameterization and global implications" by Stuart et al. (2013), Atmos. > Chem. Phys., 15, 753-756, doi:10.5194/acp-15-753-2015, 2015. > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > > > ------------------------------ > No infections found in this outgoing message > Scanned by *iolo System Shield* > http://www.iolo.com > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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