[CQ-Contest] NW7US Propagation Update: 20-XII-2003

Tomas NW7US nw7us at hfradio.org
Sat Dec 20 08:08:44 EST 2003

Hello, Radio Enthusiast!

Currently, there is an elongated coronal hole in geoeffictive position
on the solar disk.  This coronoal hole is quite a bit smaller than the
coronal hole of last week.  

The solar wind speed is currently above 460 km per second, but the 
Interplanetary Magnetic Field (IMF) currently has a northerly 
orientation (the "Bz" is positive).  There have been brief moments 
with the Bz going negative (the IMF orientation goes south), so we are 
seeing the geomagnetic field becoming more active.

Currently the planetary K index (Kp) is 3, down from 4.  I am expecting
this fluctuation to continue until Monday, with swings between active
to minor storm levels.  

This ultimately translates to slightly degraded ionospheric conditions, 
with the maximum usable frequencies (MUFs) just a bit depressed from 
normal.  The highest HF bands suffer under these conditions, and mid-HF 
openings over high-latitude and polar paths become weaker, and of 
shorter duration.  Again, by Monday, we should start to see conditions 
settling down and HF propagation becoming excellent.  The 10.7-cm flux
is above 120, so we'll be seeing nice higher-band HF propagation 
through the next week.

On VHF, I don't expect strong enough geomagnetic activity to trigger
any Auroral-mode propagation.  There might be a few periods of 
sporadic-E (Es) activity, however (we often see a return of Es during
December and January).  The current 10.7-cm flux is above 120, so
I also do not expect any significant F-layer propagation opening on

Happy Dxing!

73 de Tomas, NW7US (AAR0JA/AAM0EWA)
: Propagation Editor for CQ, CQ VHF, and Popular Communications :
: Quarterly Propagation Columnist for Monitoring Times Magazine :
: Creator of live propagation center - http://prop.hfradio.org/ :
: Member, US Army Miltary Affiliate Radio Service (MARS) AAR0JA :
: 122.93W 47.67N / Brinnon, Washington USA - CN87 - CW/SSB/DIGI :
: Washington State MARS Emergency Operations Officer -- AAM0EWA :
: 10x56526, FISTS 7055, FISTS NW 57,  AR Lighthouse Society 144 :

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