[South Florida DX Association] NW7US Propagation Update: 20-XI-2003

[Bill Marx]

 A severe geomagnetic storm is in progress at this time.  As I
> write this bulletin, the planetary K index (Kp) is at 7.  The
> Aurora Index is at 10 (maximum).  The Bz (horizontal component of
> the Interplanetary Magnetic Field) is strongly negative (oriented
> southward), at -55.1 nanoTeslas.  This stormy geomagnetic activity
> is causing strong ionospheric recombination, decreasing the
> maximum usable frequencies on all radio link paths.  HF propagation
> at all latitudes is poor.
> 
> This geomagnetic storm is a result of the arrival and passage of a
> coronal hole mass ejection from 18-XI-2003.  The solar wind speed
> increased from 430 km per second to 750 km per second, with a very
> strongly negative horizontal IMF component.  Whenever the Bz is 
> negative (whenever the horizontal IMF component is oriented 
> southward), the IMF combines with the magnetosphere in such a way
> as to create geomagnetic disturbances and ionospheric storms.
> Aurora is also a typical result of such interaction.
> 
> This geomagnetic storm is expected to continue through the end of
> 20-XI-2003.  Additional CME arrivals may continue to keep the 
> geomagnetic activity high.
> 
> At 0747Z, 20-XI-2003, a flare peaked at M9.6, further causing 
> degradation of the HF propagation, on the sunlit area of the Earth.
> Continued C, M, and possible X flares are possible today and for
> the next week.  The major sunspot groups from the end of October
> and the beginning of November have and are returning into view,
> increasing solar activity.
> 
> Today's HF propagation outlook is poor.  While the 10.7-cm flux 
> is climbing, the continued geomagnetic storm will significantly
> degrade higher frequency propagation.  The moderate to major flare
> activity expected will also degrade mid-HF frequencies.  Nighttime
> propagation on low to mid HF frequencies will also suffer, as the
> E-layer will be significantly recombined, decreasing its MUF.
> 
> VHF propagation via Aurora, Aurora-E, and Trans-equitorial 
> propagation (TEP) will be fair to good.  I welcome reports, if
> any, of your success on VHF during this period.
> 
> More information as events warrent will be posted in follow-up
> bulletins.  Live information is on-going at
> http://prop.hfradio.org/ and a discussion is at
> http://hfradio.org/forums/
> 
> 
> 
> 73 de Tomas, NW7US (AAR0JA/AAM0EWA)
> --
> : Propagation Editor, CQ/CQ VHF/Popular Communications Magazines :
> : http://hfradio.org/ -- http://prop.hfradio.org/ -- Brinnon, WA :