Stratospheric Aerosol Optical Thickness
Since Pinatubo there have been no major volcanic eruptions, but in the past decade the series of minor eruptions have been increasing the aerosol level.
Also available in PDF
Data source: Updates of M. Sato, J.E. Hansen, M.P. McCormick and J.B. Pollack (1993) "Stratospheric Aerosol Optocal Depth, 1850-1990", JGR, 98, 22,987-22,994.
We thank Dr. Adam Bourassa of University of Saskatchewan and Dr. Alan Robock of Rutgers Univeristy for providing 2002-2012 data, which were updates of the data used for Fig.1 in
A.E. Bourassa, A. Robock, et al. (2012) "Large Volcanic Aerosol Load Linked to Asian Monsoon Transport", Science, 337, 78-81.
Data are through December 2012. Also available in PDF.
The relation between the optical thickness and the forcings are roughly.
Source: J. Hansen, et al. (2005), "Efficacy of climate forcings", JGR, 110, D1104.
- instantaneous forcing Fi (W/m2) = -27 τ
- adjusted forcing Fa (W/m2) = -25 τ
- SST-fixed forcing Fs (W/m2) = -26 τ
- effective forcing Fe (W/m2) = -23 τ
See a NASA/GISS page for more
(Last modified: 2013/03/26)