X11-class flare 29-X-2003
 

Quick update:

At least an X10 or X11 class flare just occurred, peaking at 2049Z
29-X-2003, adding to the already dead HF conditions due to the CME passage
and the Kp = 7. This one is a short-lived flare. Quick recovery is
expected. I don't know, yet, what CME might be associated, if any.
Details, soon.

At the moment, most of the HF spectrum is "closed" to propagation, not
because of the flare. I'm have not been hearing signals here in the
Pacific Northwest on most of the HF, before the X11 flare. On many e-mail
reflectors, I am reading some folks as saying, "Wow, that X17 flare sure
has shut down the bands." Actually, it is not that solar flare that messed
up the bands, today. Flares tend to cause radio blackouts that might last
from a half hour to a number of hours. On the otherhand, major geomagnetic
storms will cause HF radio propagation degradation because of
"recombination."

Today's general outage is due to the passage of one of the fastest moving
coronal hole mass ejections on record. It caused the highest Kp index - a
level 9 geomagnetic storm. Since it hit us, the Kp index has remained at
or higher than 7. This is a severe geomagnetic storm. During a
geomagnetic storm, the ionosphere experiences "recombination" - much like
what happens at night. The maximum usable frequencies fall - sometime no
HF propagation is possible, because the ionosphere is completely
recombined... this is what is happening at this moment. Most of the HF
spectrum is "shut down."

Now, added to this geomagnetic storm and the general closure of the HF
spectrum, we have this new X11-class flare from 2049Z. I don't yet know if
a CME was associated with this one.

More as details become available...


73 de Tomas, NW7US (AAR0JA/AAM0EWA)
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