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 :
: 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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