U.S. Air Quality

Special Feature: High Altitude Aerosols across the N. Hemisphere

The Global Atmosphere Watch Atmospheric Lidar Network (GALION) listserve has distributed a number of observations of 14-18 km high aerosol plumes. There are two potential sources for these aerosols. The Sarychev Volcano exploded dramatically on June 9, 2009, and it is possible that the aerosols aloft are from this eruption. The time constant for SO₂ to SO₄ is about 28 days so more than half of the sulfur dioxide should have been converted to aerosol by this point. Also the NASA image in the link above shows that there was a lot of ash injected in the initial explosion.

However, there was a pyrocumulus fire noted a few days ago by Mike Fromm at NRL over the Canadian Yukon. Smoke from those fires have been noted in the previous posts on this site. This Minto Flats South, Alaska, fire is also a potential source of the smoke.

Here are some dramatic CALIPSO images of these high altitude layers.

Ground based lidar in Dalhousie University, Halifax, NS, Munich, Germany, Leipzig, Germany, Belsk, Poland, Paliseau, France, GSFC and, yes, even at UMBC, have seen these extended aerosol layers.

So, my take on this is that these layers are Savychev and not smoke. I base this on the fact that these highly filamented thin layers have been seen west of Alaska and that the aerosol scattering is clearly increasing with time. I present three Google Earth mapped CALIPSO cross sections, each separated by one week.

June 25:

July 2:

July 7:

The low lying aerosol in the last image is likely from the Minto Flats South, Alaska, fires and it is constrained to the lower trop on July 7.

Posted by Ray Hoff at July 11, 2009 10:45 AM