Recent Solar Flare

[ROBBARISH@aol.com]

Although the news media were somewhat sensitized to the aftermath of a 
coronal mass ejection (CME) that occurred on the sun last week, there was 
only a small impact of that event on radiation dose rates at airliner 
altitudes. Although the low energy proton flux at satellite altitude was 
increased in intensity during a period lasting about three days, the high 
energy components only were elevated for a very brief period on 10 June. This 
circumstance serves to demonstrate the difficulty in predicting the 
radiological consequences of these events. I activated the first level of 
warning on 1-877-SUNFLARE for a period of about one hour on Saturday and then 
went back to the baseline message after watching the high-energy particle 
flux "turn over" and head back to its normal levels in a rapid manner.

The July issue of Health Physics has correspondence related to the NOAA Space 
Weather scales. You may recall that I was quite concerned that the original 
highly publicized release essentially discounted any radiological impact of 
even a major CME, one producing a proton flux that would achieve ground-level 
event status. As you'll see in the journal and at the NOAA web site, the 
space weather scale has been modified in a reasonably appropriate way. See 
http://sec.noaa.gov. Also, Les Slaback was curious if the pause in the solar 
wind last year allowed for a significant increase in ground-level dose rate. 
It did not. The only ground level events (GLEs) of this cycle occurred on 6 
November 1997, 2 and 6 May 1998, and 4 Aug 1998. 

Robert Barish
robbarish@aol.com
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