[HQRP] Fwd: PROP: Storm in Progress

[Ed Manuel (N5EM)]

>Date: Fri, 3 Dec 1999 12:49:49 -0700 (MST)
>Reply-To: na5n@rt66.com
>Sender: owner-qrp-l@Lehigh.EDU
>From: "Paul Harden, NA5N" <na5n@rt66.com>
>To: "Low Power Amateur Radio Discussion" <qrp-l@Lehigh.EDU>
>Subject: PROP: Storm in Progress
>X-To: qrp-l@lehigh.edu
>X-Authentication-Warning: shell.rt66.com: na5n owned process doing -bs
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>
>Gang,
>All the active regions of the sun, that has produced the recent flares
>and trouble, has rotated beyond view on the sun.  However, a fairly large
>coronal hole has now rotated into "geoeffective" position.  This means
>it is near the central meridian of the sun, the "window" where activity
>on the sun will likely (eventually) hit the earth.
>
>Coronal Holes are not all that well understood, but they are holes or
>"tears" on the solar surface that allows energetic particles to escape
>the sun's gravitational and magnetic fields and be flung into space.
>In the case of these "geoeffective" coronal holes, the particles flow
>outward to ride along with the solar wind, adding velocity and density
>to the electrons in the solar wind.  The solar wind constantly pushes
>against the earth's magnetic field, distorting it into a torpedo shape
>(the blunt end facing the sun, the "tail" extending beyond our moon).
>Sudden changes to the velocity and/or density of the solar wind pushing
>against our magnetic field causes changes in it's shape, often causing
>it to "wiggle" from the arriving shock wave or constant changes in solar
>wind.  When this happens, our moving magnetic field generates huge
>amounts of currents that flows between our poles, causing noise on the
>HF bands.
>
>Our magnetic field has been exceptionally quiet (K index 1 and 2) past
>few days.  The increased velocity in solar wind, caused by this coronal
>hole, arrived to push against our magnetic field this morning (North
>America time), triggering a MINOR geomagnetic storm, K index of 4, which
>may go higher as the day goes on.  The 24-hour average (the A-index) will
>probably be in the 20-30 range for today.  (That information becomes
>available later this afternoon - and I'll post the numbers).
>
>The good news is ... as the earth rotates into darkness, the solar wind
>is pushing against our magnetic field AWAY from us, so conditions will
>tend to quiet down some this evening.  Tomorrow, during daylight hours,
>if the solar wind is still variable from the coronal stream, the
>disturbance will become more evident again.
>
>The forecast from NOAA suggests erratic minor storm conditions, as a
>result of this coronal stream riding along the solar wind, to persist
>over the next 2-3 days.  This does not mean conditions will be lousy 
>24-hours a day, but "on and off" for 2-3 hour periods as our magnetic
>field responds to the variations in the solar wind.
>
>A minor storm does not shut down HF communications ... just makes the
>lower bands, like 40M, a bit more noisy than normal, and may be
>accompanied by bursty static crashes as our magnetic field "wiggles."
>Levels may also be ACTIVE, or just shy of minor storm activity.
>
>I'll post an update around 5pm, after today's RSGA report is issued.
>Current conditions, including the 3-hour K-index numbers, are broadcast
>on WWV at 17 minutes past the hour, and several internet sites.  K of 4
>or higher, indicates disturbed conditions.
>
>72, Paul NA5N
>
>
>

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