AirNow reported moderate levels in different regions such as the Mid-Atlantic, Great Lakes and Pacific Northwest. In particular, California reached levels from moderate to unhealthy in the San Joaquin Valley for most of the day (top left). As far as fires is concerned, HMS detected several fires in Kansas, Oklahoma, Missouri, Arkansas, and Louisiana (top right). However none of those fires are producing significant smoke.
SPECIAL FEATURE: Ozone's Long Path to Recovery
The holes that formed in the ozone layer over Antarctica in 2011 and 2012 are a study in contrasts. The 2011 hole (bottom left) ranked among the ten largest recorded since the 1980s, while the 2012 hole (bottom right) was the second smallest. Why were they so different? Is it a sign that stratospheric ozone is recovering? These are the questions NASA scientists Anne Douglass, Natalya Kramarova, and Susan Strahan asked as they examined the holes using data from instruments on NASA's Aura and NASA/NOAA's Suomi NPP satellites.
The images above represent the typical method of gauging the ozone hole. They show the extent (the geographic area covered) and the depth (the concentration of ozone from top to bottom in the atmosphere) as measured by Aura's Ozone Monitoring Instrument. Blues and purples represent the lowest ozone levels. Each image shows the day of maximum extent--when the ozone hole was largest that year.
But the view of area doesn't tell the whole story, said Douglass. It says nothing about the chemistry or atmospheric dynamics that give the hole its shape. And if we don't know why the size and depth of the hole varies, it is impossible to know if policies meant to reduce ozone depletion (such as the Montreal Protocol) are having an impact. 2011 and 2012 offer prime examples. The Antarctic ozone hole forms in the southern spring when chlorine and other ozone depleting chemicals interact with sunlight to destroy ozone. It would be easy to assume that a larger ozone hole means more chemicals were present, but the real picture is more complicated.(Full article: Earth Observatory)