Friday, March 23, 2007

Solar blast from the past dwarfed modern ozone destruction

As we mentioned the most observable phenomena from the sun is during solar flares,where paradoxically,it is at its most energetic it actually causes cooling of the terrestrial climate due to ozone depletion.

As is wll known the presence of nitrates in the ice cores are a good indicator of high energy solar and cosmic ray activity,each having similar upper atmosphere mechanisms.An intersting paper published this week begs the obvious question,what if the Antarctic Ozone hole has always been present?.

A burst of protons from the Sun in 1859 destroyed several times more ozone in Earth's atmosphere than did a 1989 solar flare that was the strongest ever monitored by satellite, a new analysis finds. When energetic protons from the Sun penetrate Earth's stratosphere, they ionize and dissociate nitrogen and oxygen molecules, which then form ozone-depleting nitrogen oxides. Thomas et al. developed a scale factor between known nitrate enhancements from recent solar proton events. By using data on nitrate enhancements in Greenland ice cores following the September 1859 burst, they used the scale factor to determine that the total energy released by that solar proton event was 6.5 times larger than the amount released in the 1989 event. Models using this energy total showed that 3.5 times more ozone was destroyed in the 1859 episode than in that of 1989. Because ozone regulates the amount of harmful ultraviolet radiation reaching Earth, the authors emphasized that understanding intense solar proton events will be important to predicting potential damage to the biosphere.

Title: Modeling atmospheric effects of the September 1859 solar flare

Authors: B. C. Thomas: Department of Physics and Astronomy, Washburn University, Topeka, Kansas, U.S.A.;

C. H. Jackman: Laboratory for Atmospheres, NASA Goddard Space Flight Center, Greenbelt, Maryland, U.S.A.;

A. L. Melott: Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas, U.S.A.

Source: Geophysical Research Letters (GRL) paper 10.1029/2006GL029174, 2007

2 Comments:

Blogger prof_bri01 said...

Hi,
It's pretty certain that the antarctic ozone hole has not always been present. Observations starting in the 1960's and continuing until the present day show an obvious and large drop after about 1980. Also, as our modeling shows, even after a large flare event the ozone depletion is only comparable to the present day hole for a couple of years. Once the depleting chemicals are gone the ozone recovers quickly.

Cheers,
Brian Thomas, Washburn University

11:43 AM  
Blogger maksimovich said...

Thanks for your response Brian to my open question on your paper.

It is easier to respond as a post.

2:32 PM  

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