Salter appears to hold that experiments with existing equipment (eg pond fogger) is not helpful, as particle size distribution is inappropriate, and power consumption disproportionate.
I would like to hear opinions on this, as my view is that establishing plume behaviour, droplet evaporation and cloud mixing is more important at this stage than the actual albedo modifications. A On 1 Jan 2015 00:47, "Rob Wood" <bobbywood2...@gmail.com> wrote: > Dear All, > > I think that some degree of coagulation given such localized point sources > of large numbers of particles is inevitable, as shown in the paper by Stuart > et al. (2013) > <http://www.atmos-chem-phys.net/13/10385/2013/acp-13-10385-2013.html>. > This will also be the case with charged particles. Nevertheless, I don't > think that this is necessarily a fundamental limitation. After all, > shiptrack formation, where even larger numbers of particles are produced, > still occurs. Coagulation must be considered in the calculations. That > said, in our recent paper (Connolly et al. 2014 > <http://faculty.washington.edu/robwood2/wordpress/wp-content/uploads/2014/06/Connolly_etal_PHILTRANS_2014.pdf>), > we found significant albedo enhancement in a parcel model even with quite > broad size distributions. The optimal median particle size becomes smaller > as the size distribution spread broadens (e.g. from coagulation). For > broader distributions typical of those produced in lab tests, the optimal > median droplet diameters need to be somewhat smaller than 0.1 micron. > > I tend to agree with Stephen that near-surface spreading due to initial > negative buoyancy from evaporation of water from the small seawater > droplets may not necessarily be a tremendous problem for the reasons he > states. This has not yet been considered in any model that I know of, but > could easily be done with large eddy models. > > Rob Wood > > > On 12/30/2014 8:35 AM, Stephen Salter wrote: > > Hi All > > Piers Forster's concern in his video about spray coagulation would be > reduced if his model had used mono-disperse drops with an electrostatic > charge as specified in our 2008 paper on sea-going hardware. > > His concern about detecting the effectiveness is because the cloud > contrast change needed to save humanity is below the detection threshold of > the human eye. However contrast can be enhanced by the superposition of > satellite aligned images. I have previously circulated some to this group > and hope that the idea will give quantitative results in a few days. > > The picture of spray plumes shown in box 3 of his IAGP practicalities note > must have been using warm air from a chimney. Depending on the temperature > and relative humidity of the surrounding ambient air there will be several > degrees of temperature drop due to the latent heat of evaporation. The > increase of density will lead to a rapid fall of the cooled air which will > spread out over the sea surface like a spilt liquid until it has been > warmed by the large area of contact with sea. You can show this fall and > dispersion very cheaply with a pond fogger, £19.99 from Maplin. We want > this dispersion because a low dose over a large area is more effective than > a high point dose. > > Forster seems to be ignoring completely the idea of coded modulation of > CCN concentration in climate models even though the satisfactory operation > was demonstrated by Ben Parkes doing a PhD in Forster's own Department at > Leeds in 2012. This might allow us to get an everywhere-to-everywhere > transfer function of marine cloud brightening and win-win result with more > rain in dry places and less in wet. The high frequency response means that > we can give a tactical spraying based local day-to-day observations. > > It is a puzzle that the Parkes thesis has, yet again, vanished from the > Leeds University website. > > Stephen > > > > Emeritus Professor of Engineering Design. School of Engineering. > University of Edinburgh. Mayfield Road. Edinburgh EH9 3JL. Scotland > s.sal...@ed.ac.uk Tel +44 (0)131 650 5704 Cell 07795 203 195 > WWW.see.ed.ac.uk/~shs <http://WWW.see.ed.ac.uk/%7Eshs> YouTube Jamie > Taylor Power for Change > On 28/12/2014 20:03, Andrew Lockley wrote: > > Integrated Assessment of Geoengineering Proposals…: > http://youtu.be/FFjzzfCLCqw > > Poster's note : I personally have found it very difficult to access and > appraise the science behind the IAGP project. Despite this, a vast amount > of publicity has been obtained for the project. I think the IAGP team could > do more to encourage early, in-depth access to their material, particularly > bearing in mind the huge media interest. > -- > 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 geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > 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. > To unsubscribe from this group and stop receiving emails from it, send an > email to geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > 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 geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > 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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