Hi All The Hoffmann paper seems to be a convincing argument to treat regions where there has just been rain to clean the air and to use a mono-disperse spray to get a high nucleation fraction. We do not want the bigger nuclei to grab water vapour and starve the smaller ones. Advice on the optimum size would be welcome. Is 0.8 micron sensible? How narrow should the spread be? Has there been any climate modelling of spread width? Stephen
Emeritus Professor of Engineering Design School of Engineering University of Edinburgh Mayfield Road Edinburgh EH9 3DW Scotland 0131 650 5704 or 0131 662 1180 YouTube Jamie Taylor Power for Change From: geoengineering@googlegroups.com <geoengineering@googlegroups.com> On Behalf Of ayesha iqbal Sent: 24 December 2022 18:55 To: geoengineering@googlegroups.com Subject: [geo] A Parameterization of Interstitial Aerosol Extinction and Its Application to Marine Cloud Brightening This email was sent to you by someone outside the University. You should only click on links or attachments if you are certain that the email is genuine and the content is safe. https://journals.ametsoc.org/configurable/content/journals$002fatsc$002f79$002f11$002fJAS-D-22-0047.1.xml Authors Fabian Hoffmann, Bernhard Mayer and Graham Feingold Online Publication: 18 Oct 2022 Print Publication: 01 Nov 2022 DOI: https://doi.org/10.1175/JAS-D-22-0047.1 Abstract Marine cloud brightening (MCB) is a geoengineering approach to counteract climate change by the deliberate seeding of sea salt aerosol particles that, once they activated to cloud droplets, directly increase cloud reflectance and hence global albedo. However, a large fraction of the seeded aerosol may remain interstitial, i.e., unactivated particles among cloud droplets. Because the consideration of interstitial aerosol optical properties usually requires computationally expensive simulations of the entire particle spectrum and direct Mie calculations, we develop a simple parameterization to be used with computationally efficient bulk and even bin cloud microphysical schemes that do not treat the unactivated aerosol explicitly. Using parcel and large-eddy simulations with highly detailed Lagrangian cloud microphysics and direct Mie calculations as a reference, we show that the parameterization captures the variability in the interstitial aerosol extinction successfully. By applying the parameterization to typical MCB cases, we find that the consideration of interstitial aerosol extinction is important for the assessment of MCB in shallow clouds with weak updrafts, in which only a small fraction of aerosol particles is activated to cloud droplets. Source: Journal of the Atmospheric Sciences -- 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<mailto:geoengineering+unsubscr...@googlegroups.com>. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/CAOyeF5s-jSW693wefs0VX18%2BhRSKZkGJO5Q80oT6fk8WsN_ueA%40mail.gmail.com<https://groups.google.com/d/msgid/geoengineering/CAOyeF5s-jSW693wefs0VX18%2BhRSKZkGJO5Q80oT6fk8WsN_ueA%40mail.gmail.com?utm_medium=email&utm_source=footer>. The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. Is e buidheann carthannais a th’ ann an Oilthigh Dhùn Èideann, clàraichte an Alba, àireamh clàraidh 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 view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/AM8PR05MB80351FB1806D58EAD58E4382A7EF9%40AM8PR05MB8035.eurprd05.prod.outlook.com.
