Stratosphere volcanic aerosols lowest since before 1960

“Earth’s stratosphere is as clear as it’s been in more than 50 years. University of Colorado
climate scientist Richard Keen knows this because he’s been watching lunar eclipses. “Since
1996, lunar eclipses have been bright, which means the stratosphere is relatively clear of
volcanic aerosols. This is the longest period with a clear stratosphere since before 1960.”
Consider the following comparison of a lunar eclipse observed in 1992 after the Philippine
volcano Pinatubo spewed millions of tons of gas and ash into the atmosphere vs. an “all-clear” eclipse in 2003:

Keen explains why lunar eclipses can be used to probe the stratosphere: “At the distance of the Moon, most of the light refracted into the umbra (Earth’s shadow) passes through the
stratosphere, which lies 10 to 30 miles above the ground. When the stratosphere is clear, the umbra (and therefore, the eclipsed Moon) is relatively bright. On the other hand, if the
atmospheric lens that illuminates the Moon becomes dirty enough, light will be blocked and the eclipse will appear dark.”

This article posted in spaceweather.com contained a link to PowerPoint presentation with in depth analysis by Richard Keen.  The gigharbortimes.com has converted the PowerPoint presentation to Adobe pdf for easier viewing:  Richard Keen’s Volcanoes and Climate Change since 1980: a view from the Moon
(Used with permission)