Dear Robert, Volcanic stratospheric aerosols do not last for decades. Less than a decade after the 1991 Pinatubo eruption, the stratosphere was at its cleanest ever observed. Of course, there is a persistent small amount of aerosols from non-volcanic sources, the Junge layer ( http://glossary.ametsoc.org/wiki/Stratospheric_sulfate_layer ).
Alan Alan Robock, Distinguished Professor Associate Editor, Reviews of Geophysics Department of Environmental Sciences Phone: +1-848-932-5751 Rutgers University E-mail: [email protected]<mailto:[email protected]> 14 College Farm Road http://people.envsci.rutgers.edu/robock New Brunswick, NJ 08901-8551 USA ☮ http://twitter.com/AlanRobock On 4/11/2019 12:09 AM, 'Robert Tulip' via geoengineering wrote: Speaking to some astronomer friends, they say the Pinatubo eruption effect was certainly measurable as a (pretty much global) change in the [X] extinction properties of the atmosphere<https://en.wikipedia.org/wiki/Extinction_(astronomy)>, adding an important "grey" aerosol contribution to the usual reddening ([X]one study<http://adsabs.harvard.edu/abs/2005JGRD..11014210S>). From New Zealand, once the particulates reached them (after about 80 days), the extinction in the V-band around 550 nm increased from 0.13 to 0.21 magnitude/airmass (similar to other temperature sites both north and south - [X] reference<http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1995Obs...115...29F&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf>). A similar change was [X] observed for the eruption of El Chichon<http://adsabs.harvard.edu/abs/2011A%26A...527A..91P>. These analyses suggest that the settling time for all measurable extinction effects of these eruptions can be decades. You can see the increase in extinction in the U, B, and V passbands very clearly in this figure [X] http://adsbit.harvard.edu/cgi-bin/t2...&filetype=.gif from the paper by Burki et al., Astronomy and Astrophysics, 112, p. 383 (1995), available at [X] http://articles.adsabs.harvard.edu/f...6AS..112..383B [X] A number of other papers by observers at other locations confirm these results. Robert Tulip On Monday, 8 April 2019, 2:01:00 am AEST, Douglas MacMartin <[email protected]><mailto:[email protected]> wrote: There’s not that much ground-based astronomy in UV, relative to optical and IR astronomy. Impact on optical astronomy is straightforward; if you lose 5% of the direct light, you need 5% longer integration time to get same number of photons. Impact on IR astronomy is less obvious, as limited by the background from the sky, which depends on water vapour and temperature through the atmospheric column (with most telescopes being at 14000’ or so). Shouldn’t be hard to estimate, I’ve never gotten someone interested enough to do the calculations but I could try again (my other job is being on the design team for the Thirty Meter Telescope). I did ask people whether they noted anything after Pinatubo, and the answer I got was no… that doesn’t mean there wasn’t an effect, but it wasn’t something that the astronomy community by and large remembered. From: [email protected]<mailto:[email protected]> <[email protected]><mailto:[email protected]> On Behalf Of Russell Seitz Sent: Sunday, April 7, 2019 9:31 AM To: geoengineering <[email protected]><mailto:[email protected]> Subject: [geo] Re: SRM optical impacts Why would reductions in the downwelling tropospheric light flux increase any of the above? I'd instead ask instrumental astromomers what they think SO2 scattering would do in the UV , as they have a lot to lose from scattered light, which can cost them contrast and degrade the signal to noise ratio in interferometry and spectroscopy. Try the Magellan and OWL teams On Wednesday, April 3, 2019 at 7:47:35 AM UTC-4, Andrew Lockley wrote: Has there been any investigation of SRM effects on vision? Eg perceived glare, macular degeneration, corneal sunburn, vision development in infants, object recognition when driving (and their equivalent in animals)? Andrew Lockley -- 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]<mailto:[email protected]>. To post to this group, send email to [email protected]<mailto:[email protected]>. Visit this group at [X] https://groups.google.com/group/geoengineering. 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