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- Subject: Info-Hams Digest V91 #208
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-
- Info-Hams Digest Thu, 14 Mar 91 Volume 91 : Issue 208
-
- Today's Topics:
- MAJOR SOLAR FLARE ALERT - HIGH IMPACT EXPECTED FOR 16 MARCH
-
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- ----------------------------------------------------------------------
-
- Date: Wed, 13 Mar 1991 16:18:32 -0500
- From: oler@HG.ULeth.CA (CARY OLER)
- Subject: MAJOR SOLAR FLARE ALERT - HIGH IMPACT EXPECTED FOR 16 MARCH
- To: info-hams@ucsd.edu
-
- -- MAJOR SOLAR FLARE ALERT --
-
- MARCH 13, 1991
- Alert #2
-
- Flare Event Summary
- ** POTENTIALLY HIGH TERRESTRIAL IMPACTS EXPECTED **
-
-
- --------
-
-
-
- MAJOR ENERGETIC EVENT SUMMARY
-
- Two additional major solar flares have occurred over the past 24 hours.
- The first major event was rated a class X1.3/2B and seems to have been
- associated with a Type IV sweep. Several Type IV sweeps have been observed
- recently. The event began at 08:00 UT, peaked at 08:08 UT and ended at 08:13
- UT. The flare was located within Region 6545 near S10E45 (unofficial). The
- flare was associated with a strong 1300 s.f.u. Tenflare at 08:02 UT.
-
- The second major flare erupted at 15:42 UT, peaked at 15:48 UT and
- ended at 16:02 UT. This event was rated a class X3.9/1N. A strong
- Tenflare of 3600 s.f.u. was also observed with this flare.
-
- Satellite protons increased to near event thresholds recently. The
- peak proton count reached 9 p.f.u. (10 is the event level). It has since
- declined and is presently holding at near 4 p.f.u..
-
- Region 6545 is a potent region containing large sunspots in close
- proximity to one another. Magnetic fields are high and gradients are
- strong. This region will continue to produce major solar flares of class X
- or M intensities. Protons could easily surpass event thresholds if flaring
- continues.
-
- Region 6538 continues to remain fairly dormant in flare output, but
- contains all of the ingredients necessary to begin major flaring again. It
- is expected to begin to produce at least M-class flares anytime now.
-
-
- POTENTIAL TERRESTRIAL IMPACT FORECAST
-
- A POTENTIALLY HIGH TERRESTRIAL IMPACT IS BEING FORECASTED FOR 15, 16
- AND POSSIBLY 17 MARCH!
-
- A MAJOR GEOMAGNETIC AND AURORAL STORM is possible on 15 and/or 16 March.
- Data obtained from Pioneer Venus show that the solar wind velocity has
- increased dramatically to values near 970 km/s with a strongly directed
- southward magnetic component. It is possible that the earth could be hit
- with some of the material streaming by this satellite. Current predictions
- estimate that the geomagnetic storming could push the A-index to levels
- near 50 on 16 March. Middle latitude magnetic K-indices are expected to
- be sustained near 5 and 6 with possible brief periods near 7 (if activity
- is more intense than expected). High latitude magnetic activity could
- surpass A-indices of 100 with associated K-index values between 7 and 9 (it
- should be noted that a K-index of 9 is the top of the scale). Magnetic
- perturbations over high latitudes could approach 1,500 to 2,000 gammas.
- Middle latitudes could see fluctuations between 100 and 250 gammas (for
- mid to southerly middle latitudes). Northerly middle latitudes could see
- fluctuations ranging from 200 to 1000 gammas.
-
- A MAJOR geomagnetic storm is possible. Storming is expected to peak
- on 16 March. A sudden storm commencement associated with the arrival of
- the interplanetary shockwave is expected sometime on 15 March. It is
- difficult to determine when this shock might hit, but preliminary estimates
- suggest that the shock could arrive near 12:00 UT on 15 March. Minor to major
- geomagnetic storming could follow shortly thereafter.
-
- A POTENTIAL LOW LATITUDE AURORAL ACTIVITY WARNING is being issued for
- 16 March. Auroral activity could become visible at southerly middle and some
- low latitude regions if storming reaches or exceeds predicted levels. High
- latitude and northerly middle latitudes could experience auroral storming
- with possible high auroral activity.
-
- Significant VHF auroral backscatter will be possible late on 15
- and on 16 March. HF conditions are expected to be quite disturbed on 16
- March. Significant fading, flutter, noise and absorption are possible. If
- storming occurs, MUF's will decrease and LUF's will increase notably.
- Updates and/or modifications to this forecast will be posted when available.
-
- Major flaring is expected to continue. Proton and/or PCA activity
- could occur anytime. Watch for possible future warnings and/or alerts.
-
- ** End of Alert **
-
- ------------------------------
-
- End of Info-Hams Digest
- ******************************
-