This is very important for engineering, as it favours high-altitude technologies (rockets, guns) vs air-breathing aircraft.
What is the optimal injection altitude, in your opinion? At some point, the aerosol or precursor would be at risk of mixing into the mesosphere. Andrew On Fri, 24 May 2019, 07:09 Govindasamy Bala, <bala....@gmail.com> wrote: > Dear All, > > This work is now published in Earth System Dynamics as a discussion paper. > When we started this work, we had hard time understanding the sensitivity > to the height of the sulfate aerosol layer. In the paper, we explain the > sensitivity in terms of the effective radiative forcing. > > > https://www.earth-syst-dynam-discuss.net/esd-2019-21/ > ESDD - Climate System Response to Stratospheric Sulfate Aerosols: > Sensitivity to Altitude of Aerosol Layer - earth-syst-dynam-discuss.net > <https://www.earth-syst-dynam-discuss.net/esd-2019-21/> > www.earth-syst-dynam-discuss.net > We find that sulfate aerosols are more effective in cooling the climate > system when they reside higher in the stratosphere. We explain this > sensitivity in terms of radiative forcing at the top of the atmosphere. > > *Abstract* > Reduction of surface temperatures of the planet by injecting sulfate > aerosols in the stratosphere has been suggested > as an option to reduce the amount of human-induced climate warming. > Several previous studies have shown that for a specified amount of > injection, aerosols injected at a higher altitude in the stratosphere would > produce more cooling because aerosol sedimentation would take longer time. > In this study, we isolate and assess the sensitivity to the altitude of the > aerosol layer of stratospheric aerosol radiative forcing and the resulting > climate change. We study this by prescribing a specified amount of sulfate > aerosols, of a size typical of what is produced by volcanoes, distributed > uniformly at different levels in the stratosphere. We find that > stratospheric sulfate aerosols are more effective in cooling climate when > they reside higher in the stratosphere. We explain this sensitivity in > terms of effective radiative forcing: volcanic aerosols heat the > stratospheric layers where they reside, altering stratospheric water vapor > content, tropospheric stability and clouds, and consequently the effective > radiative forcing. We show that the magnitude of the effective radiative > forcing is larger when aerosols are prescribed at higher altitudes and the > differences in radiative forcing due to fast adjustment processes can > account for a substantial part of the dependence of amount of cooling on > aerosol altitude. These altitude effects would be additional to dependences > on aerosol microphysics, transport, and sedimentation, which are outside > the scope of this study. The cooling effectiveness of stratospheric sulfate > aerosols likely increases with altitude of the aerosol layer both because > aerosols higher in the stratosphere have larger effective radiative forcing > and because they have a longer stratospheric residence time; these two > effects are likely to be of comparable importance. > -- > With Best Wishes, > > ------------------------------------------------------------------- > G. Bala > Professor > Center for Atmospheric and Oceanic Sciences > Indian Institute of Science > Bangalore - 560 012 > India > > Tel: +91 80 2293 3428; +91 80 2293 2505 > Fax: +91 80 2360 0865; +91 80 2293 3425 > Email: gb...@iisc.ac.in; bala....@gmail.com > Web: http://dccc.iisc.ac.in/bg.html > ------------------------------------------------------------------- > > -- > 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 https://groups.google.com/group/geoengineering. > To view this discussion on the web visit > https://groups.google.com/d/msgid/geoengineering/CAD7fhV%3D9Qko-S681Y3vS7qdgK3n7LFZ0_6FCJdDkE9VffPR6RQ%40mail.gmail.com > <https://groups.google.com/d/msgid/geoengineering/CAD7fhV%3D9Qko-S681Y3vS7qdgK3n7LFZ0_6FCJdDkE9VffPR6RQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > 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 https://groups.google.com/group/geoengineering. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/CAJ3C-067C-sq55NaVUemEa9Wf9%2B7tpRY08%3DQKjjrm9%2B_Yqb8DQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
