[PPRAANet] New NOAA Solar Storm Scales

[W0rw@aol.com]

Gang,
Recently, various organizations, most notably the National Oceonographic
and Atmospheric Administration (NOAA), has adopted a "new" set of scales
to better communicate to the public the anticipated effects of solar and
geomagnetic storms.  Actually, there is nothing new about these scales
at all, they have been around for years and on the NOAA websites, but have
seldom been used.  As of April 1, 2002, most agencies are now using these
scales, including NOAA solar alerts and the hourly WWV solar and
geomagnetic updates.

Here is a synopsis of the new scales.  The complete tables can be
found at: http://www.sec.noaa.gov/NOAAscales

GEOMAGNETIC STORMS
==================
CLASS Kp=   STORM     EFFECTS TO HF PROPAGATION   AURORA
-------------------------------------------------------------------------
  G1  Kp=5  Minor     Minor noise & fading        Extreme high latitudes
  G2  Kp=6  Moderate  Fading at higher latitudes  Aurora US/VE border
  G3  Kp=7  Strong    Intermittent                From Oregon to Illinois
  G4  Kp=8  Severe    Very difficult & sporadic   From N. CA to AL 
                      & poss. power grid failures
  G5  Kp=9  Extreme   Near or total HF blackout   To S. Tex. and Florida
                      & poss. power grid failures                   
-------------------------------------------------------------------------

SOLAR(RADIO) STORMS
===================
CLASS FLARE STORM     EFFECTS TO HF PROPAGATION
-------------------------------------------------------------------------
  R1  M1    Minor     Weak degradation
  R2  M5    Moderate  Limited blackouts on sunlit side of Earth
  R3  X1    Strong    HF blackout on sunlit side; limited elsewhere
  R4  X10   Severe    Global HF blackout, 24 hour duration
  R5  X20   Extreme   Global HF blackout, 2-3 day duration
-------------------------------------------------------------------------

A few definitions:
Kp = planetary K-index of geomagnetic disturbances.  The K-index is
     measured every 3 hours and reported on WWV and www.sec.noaa.gov
     The 24-hour average is called the A-index
Flare = the approximate size of the solar flare triggering the solar and
     radio storm.

A reminder ...
When a major flare occurs, it produces a solar/radio storm immediately
and will persist from tens of minutes to 2-3 hours.  Then it's over.
This is from the speed-of-light (relativistic) energy being released by
the flare event.

If the solar flare is located near the center of the sun and produces a
CME (Coronal Mass Ejection), the shockwave from the CME will most likely
hit the earth and trigger a geomagnetic storm.  This shockwave travels
about 500-1200 km/sec., and takes 2-3 days to reach the earth.  Thus, a
geomagnetic storm will occur 2-3 days AFTER the flare event, and this
storm will last hours to a full day in duration.  This shockwave is what
also triggers aurora.

72, Paul NA5N
via w0rw