NW7US Propagation Bulletin Update
0930 UTC, 17 January 2005
It is clear now after analysis that the coronal mass ejection (CME)
associated with the X2.6-class X-ray flare of 2302 UTC 15 January 2005 has
arrived. The first detection was at 0640 UTC as an energetic ion
enhancement. The second was a moderate shock reported at 0716 UTC by ACE.
This is the second CME expected between 16 and 18 January 2005. The first
CME, associated with the long-duration M8.6-class flare of 15 January 2005
(0639 UTC), appears to have arrived around 0930 UTC 16 January 2005, when
we saw the planetary K index (Kp) reach 5, and the solar wind speed
increase with a change in the interplanetary magnetic field (IMF).
The second CME that has now arrived is pushing the solar wind speed to
above 600 kilometers per second. The IMF has been become
southward-oriented for only short periods of time. However, I expect the
IMF to move more steadily southward as this CME plasma cloud passes,
increasing the geomagnetic disturbance already detected. As stated
earlier, forecasters are expecting major to severe geomagnetic storminess
in the next 12 hours, extending for the next 24 to 48 hours. This will
depress the maximum usable frequencies on HF ionospheric radio paths. At
the same time, these conditions are and will continue to spawn Aurora.
Radio Aurora has been reported.
As I write this (0930 UTC), it is also clear that we are in the middle of
another long-duration X-class flare. The rise-time of this flare event
has been over one-hour in length, and the peak has not yet been reached.
This is an event to keep our eyes on, as any CME associated with this will
likely cause at least a glancing blow in about three days. During the
course of this flare, radio blackout is causing degradation of HF
communications on the day-lit side of the Earth. The flare was declared
as an active event at 0659 UTC (17 January 2005) at a level of C1.1. The
current GEOS 12 measurement at 0927 UTC is at X1.4 (GEOS 10 is recording
X1.5), and still climbing. This is a VERY long rise-time. Most flares
begin and end within minutes to at most a half-hour.
Updates when possible and if warranted will be issued.
73 de Tomas, NW7US (AAR0JA/AAA0WA)
: Propagation Editor for CQ, CQ VHF, Popular Communications :
: Creator; live propagation center http://prop.hfradio.org/ :
: Associate Member of Propagation Studies Committee of RSGB :
: US Army Miltary Affiliate Radio Service (MARS) SMD AAA0WA :
: 122.93W 47.67N / Brinnon, Washington USA CN87 CW/SSB/DIGI :
: Website/software/database design http://newwebmakers.com/ :
: 10x56526, FISTS 7055, FISTS NW 57, Lighthouse Society 144 :
--
73 de Tomas, NW7US (AAR0JA/AAA0WA)
: Propagation Editor for CQ, CQ VHF, Popular Communications :
: Creator; live propagation center http://prop.hfradio.org/ :
: Associate Member of Propagation Studies Committee of RSGB :
: US Army Miltary Affiliate Radio Service (MARS) SMD AAA0WA :
: 122.93W 47.67N / Brinnon, Washington USA CN87 CW/SSB/DIGI :
: Website/software/database design http://newwebmakers.com/ :
: 10x56526, FISTS 7055, FISTS NW 57, Lighthouse Society 144 :
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