[CQ-Contest] Arrival of the expected CME 19-I-2005 0030Z

nw7us at hfradio.org nw7us at hfradio.org
Tue Jan 18 19:40:43 EST 2005

NW7US Propagation Bulletin / Update
19 January 2005 - 0030Z

There is speculation that the coronal mass ejection unleashed by the X3.8  
level flare from active region 720 may have arrived.  It is very difficult  
to determine exactly when, if indeed it has, arrived.  The reason for this  
lies in the extreme to very strong proton storm that has caused a  
saturation / contamination of the instruments that we measure the solar  
wind data with.  Without reliable measurements, we are not yet sure of the  
details needed to pinpoint the arrival of the CME.

However, the solar wind speed readings are beginning to become reliable,  
and we have some spotty information that the wind speed was over 900  
km/s.  At the same time, the interplanetary magnetic field appears to be  
oriented northward.  Even so, with a wind pressure this strong compressing  
the magnetosphere, the geomagnetic field will increase in its activity, to  
severe storm levels.  Aurora is a pretty sure bet.  If/when the IMF turns  
southward for more than a few hours, the storm will increase significantly  
(Kp >= 8).  We are still under a strong proton storm with a polar cap  
absorption event.

Bottom line:  Fire up your VHF for AU mode propagation.  Look for visual  
aurora even in lower latitudes.  Tonight in North America, the Northern  
Lights will play, and they may well be quite a show.  At the same time, as  
the storm picks up, the maximum usable frequencies on HF will become  
greatly depressed, making communications difficult on many signal paths.   
Medium Wave propagation will continue to have antinuation, especially over  
high latitude paths.


73 de Tomas, NW7US (AAR0JA/AAA0WA)

: Propagation Editor for CQ, CQ VHF, Popular Communications :
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