Alan Robock recently told a Chapman conference http://www.youtube.com/watch?v=6AENZJEB78E
to expect soot clouds launched above and below the tropopause to produce prolonged negative forcing . On Thursday, July 11, 2013 6:23:50 PM UTC-4, andrewjlockley wrote: > > Poster's note : This is a game-changing piece of research. Finding > we have up to 0.8 W/m2 of previously 'hidden' warming is a spectacular > result. It also suggests a possible contradiction with Kravitz' > result on the use of soot, albeit his paper was analysing > stratospheric (not tropospheric) soot injections. > > NB Link is to abstract only. Paper will hopefully be in PNAS > http://www.daca-13.org/wsl/daca13/program/DACA-13_Abstract_Proceedings.pdf > > Radiative forcing by aircraft: effects of soot on large-scale clouds > Joyce Penneret al > > Radiative forcing by aircraft soot in large-scale clouds has been > estimated to be both positive and > negative, while forcing by contrails and contrail cirrus (i.e. > spreading contrails) is positive. Here we use > an improved model to estimate the forcing in large-scale clouds. We > assume that the fraction of soot > particles that have been processed through contrails are good > heterogeneous ice nuclei (IN) and use > the average fraction determined from the CoCiP model. The calculated > total all-sky radiative climate > forcing ranges between -0.2 and -0.8 Wm-2 > , with the range determined by whether sulfate on soot > decreases their ability to act as IN as well as the treatment used for > precipitation scavenging. We > discuss what is needed to narrow the range. > -- 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]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/groups/opt_out.
