Kasatochi Remnants Question

[Paul Hadfield]

Last night while out with my daughter at a local park, I noticed faint crepuscular rays that have been a trademark of our fair wx sunsets since the beginning of August. These rays are the result of sunlight bouncing off of high altitude volcanic emissions generated by Mt. Kasatochi on August 7, 2008. What I am curious to know is just how long does it take for ashfall to scrub out of the atmosphere and where does all that debris go? Does it congeal and fall back to earth or remain suspended indefinite? More pics from the evening here.

Related links

http://www.avo.alaska.edu/activity/Kasatochi.php

http://www.avo.alaska.edu/image.php?id=15049

 

[Gregg Gallina]

Paul,

Though I cannot fully discount the possibility of some SO2 and sulfuric acid still suspended in the atmosphere, the likelihood of the density is likely lower than local area pollution and general background scattering molecules/particulates densities. At work, we tracked at least 3-4 circumnavigations of the SO2 signatures from satellite imagery (via OMI - SO2 sensor) but they have decreased below detectable levels for over a month now. (OMI imagery here - http://satepsanone.nesdis.noaa.gov/p...SO2/index.html ) .

Still to answer your original question of length of fallout, with these volcanic gases reaching the stratosphere and the extremely light weight of these molecules, it would take a significant mixing downward through the tropopause, possibly through stratospheric intrusions with very strong mid-latitude cyclone development? And the amount of air that actually does this each year would guess is small, hence the reason it takes such a long time for large eruptions/nuclear winter conditions to break down...and why I am still confident that there are still a good amount of Kasatochi particles still up there. It took Pinatubo ash/gases over 2 years to mix out to low enough levels, but that was a MUCH larger eruption AND it was cross-equatorial, since it was in the tropics and so affected a much larger area.

Gregg

PS.
My job is satellite analysis...and work at the Washington Volcanic Ash Center tracking ash via satellite, just to give a bit of credibility to my answer...though I am far from the best expert. I just hope I helped.

 

[Paul Hadfield]

Thank you for taking the time to comment on my inquiry. The last significant volcanic eruption in the N Hemisphere that I remember was Mt. St. Helens and as a kid, the last thing I was paying attention to were the sunsets.

 

[Chris Nuttall]

I'm surprised you don't remember the Mt. Pinatubo eruption in 1991. That event was more powerful than Mt. St. Helens, and more historic for a number of reasons. Wikipedia has a good page on it.

 

[Paul Hadfield]

I'm surprised you don't remember the Mt. Pinatubo eruption in 1991. That event was more powerful than Mt. St. Helens, and more historic for a number of reasons. Wikipedia has a good page on it.

I do remember the event from being in the news but not what if any effects over the N. Hemisphere either personally observed or reported for that matter. There too I was a HS junior in PA working two jobs; preoccupied with cars and girls when not so could've been? lol

Does anyone remember the better part of N. America seeing any aerosol activity?

http://www.jpl.nasa.gov/earth/images/air_image.gif

(you're right about the wiki link, very good)