An updated version of this (still unpublished and not peer reviewed) paper is now available at: http://www.atmos.ucla.edu/~csi/REF/abstracts/absBernstein_etal.html
http://www.atmos.ucla.edu/~csi/REF/pdfs/BernsteinEtal2012.pdf http://www.atmos.ucla.edu/~csi/REF/pdfs/BernsteinEtal2012_Supp.pdf Could aerosol emissions be used for regional heat wave mitigation?*D. N. Bernstein, J. D. Neelin, Q. B. Li, and D. Chen* Atmos. Chem. Phys., submitted, 7/2012. ---- As a side note, there seems to be a fair amount of disagreement regarding the wisdom of distributing pre-publication drafts. On the one hand, it allows for identification of errors before peer-reviewed publication and helps distribute information. On the other hand, it allows a lot of work that should be filtered out to be broadly distributed. I tend to think that there is already too much to read and too much junk circulating around and that science is better served by waiting until papers have been through the peer review process so that we can have some sort of (imperfect) filter to help identify what is actually worth reading and paying attention to. However, EGU journals have gone to publishing submissions as "Discussion" papers, so it seems I might be in the minority. On Wed, Jul 11, 2012 at 10:04 PM, David Neelin <[email protected]>wrote: > Ken, & all, > Thanks for your kind comments. > I'm attaching an updated version of the manuscript. [The one you sent with > your e-mail was a version we had circulated informally for comments > presubmission]. The main differences in the current version (submitted to > ACP) in response to comments we had received so far are additional caveats > placed in the introduction that more carefully bound what is being > evaluated with the tool at hand (WRF-Chem), and reiterating cautionary > sentences on the need for evaluation, plus spelling out a few more model > set up aspects etc. > > In response to just a couple of the thoughts below: > For the smaller (SoCal) sized emission areas it's more like O(10^-3) of > global; > But this is still sizable (Gg). Hence the list of concerns at the end, > including the fact that an emissions level chosen for low flow speed has > serious trade-offs wrt optimizing global or downstream effects (~12km used > here illustrates this point). > We regard this as providing initial pieces of information that could be > used in assessment of an application that's bound to come into discussion, > but about which we share deep reservations. > Best > David > > > On 7/11/2012 12:57 AM, Ken Caldeira wrote: > > Yes this is interesting and novel work. As Greg points out, it would be > very interesting to see how results scale with the altitude of injection. > > If I read their numbers correctly, they are injecting at on the order of > 1% of what might be needed for an offsetting of global 2xCO2. > > Does anybody have any sense of what the amounts injected mean in terms > of local health effects etc? > > > > > On Tue, Jul 10, 2012 at 8:21 PM, Gregory Benford <[email protected]>wrote: > >> Very interesting work. I wish it included the actual heights chosen to >> release aerosol (held constant, or varied with location? etc), the >> dispersion rates, and the granulation in cooling effect. >> >> Gregory Benford >> >> >> On Tue, Jul 10, 2012 at 10:09 AM, Josh Horton >> <[email protected]>wrote: >> >>> Hi all, >>> >>> Here is an abstract and link for an interesting manuscript on aerosol >>> injections to combat regional heatwaves, in this case California. It >>> touches on both regional schemes and the sometimes blurry line between >>> geoengineering and weather modification. >>> >>> Josh Horton >>> [email protected] >>> http://geoengineeringpolitics.blogspot.com/ >>> >>> >>> http://www.atmos.ucla.edu/~qli/publications/Bernstein_2012_ACPD.pdf >>> >>> Could aerosol emissions be used for regional heat wave mitigation? >>> >>> Abstract. Geoengineering applications by injection of sulfate >>> aerosols into the stratosphere are under consideration as >>> a measure of last resort to counter global warming. Here >>> adaptation to a potential regional-scale application to offset >>> 5 the impacts of heat waves is critically examined. The effect >>> of regional-scale sulfate aerosol emission over California >>> in each of two days of the July 2006 heat wave using the >>> Weather Research Forecast model with fully coupled chemistry >>> is used to quantify potential reductions in surface tem10 >>> perature as a function of emission rates in the lower stratosphere. >>> Over the range considered, afternoon temperature >>> reductions scale almost linearly with emissions. Local meteorological >>> factors yield geographical differences in surface >>> air temperature sensitivity. For emission rates of approx15 >>> imately 30 g mô€€€2 sô€€€1 over the region, temperature decreases >>> of around 7 C result during the middle part of the >>> day over the Central Valley, one of the hardest hit by the >>> heatwave. Regions more ventilated with oceanic air such as >>> Los Angeles have slightly smaller reductions. The length >>> 20 of the hottest part of the day is also reduced. Advection effects >>> on the aerosol cloud must be more carefully forecast for >>> smaller emission regions. Verification of the impacts could >>> be done via measurements of differences in reflected and surface >>> downward shortwave. Such regional geoengineering ap25 >>> plications with specific near-term target effects but smaller >>> cost and side effects could potentially provide a means of >>> testing larger scale applications. However, design trade-offs >>> differ from global applications and the size of the required >>> emissions and the necessity of emission close to the target >>> 30 region raise substantial concerns. The evaluation of this regional >>> scale application is thus consistent with global model >>> evaluations emphasizing that mitigation via reduction of fossil >>> fuels remains preferable to considering geoengineering >>> with sulfate aerosols. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "geoengineering" group. >>> To post to this group, send email to [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]. >>> For more options, visit this group at >>> http://groups.google.com/group/geoengineering?hl=en. >>> >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "geoengineering" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/geoengineering?hl=en. >> > > > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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