:Product: Weekly Highlights and Forecasts
:Issued: 2000 Oct 24 2112 UT
Highlights of Solar and Geomagnetic Activity
16 - 22 October 2000

Solar activity varied from low to moderate levels. The period began
with activity at moderate levels due to a long-duration M2 X-ray
flare at 16/0728 UTC with associated Type II and IV radio sweeps.
This flare likely originated from old Region 9182 (N02, L = 246,
class/area Dai/360 on 11 October), which was a day and a half beyond
the west limb at the time of the flare. There was also a halo CME
associated with this flare, but it was not Earth-directed. Activity
decreased to low levels during 17 - 20 October with isolated B- and
C-class subflares. Activity rose to moderate levels on 21 October
with an M3/1n flare from Region 9201 (N17, L = 054, class/area
Eai/250 on 22 October), which was in a gradual growth phase at the
time of the flare. Activity returned to low levels on the last day
of the period.

Data were available from the Advanced Composition Explorer (ACE)
spacecraft for most of the period. A negative polarity coronal hole
signature was observed during 16 - 17 October. Peak wind velocities
of 630 Km/sec occurred on 16 October, then gradually declined to
nominal velocities by 18 October. IMF Bz fluctuated around zero in
the plus 07 to minus 06 nT (GSM) range through 18 October. Another
coronal hole signature began on October 22 as velocities increased
from 380 to 630 km/sec and densities became low. IMF Bz fluctuated
between plus 10 and minus 11 nT as coronal hole effects began. Phi
readings indicated that this was a positive polarity hole.

A greater than 10 MeV proton event at geosynchronous orbit was
associated with the long-duration M2 flare at 16/0728 UTC. The event
began at 16/1125 UTC, reached a maximum of 15.1 pfu at 16/1840 UTC,
and ended at 17/0210 UTC. The greater than 100 MeV proton flux was
enhanced on 16 October following the flare.

The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels during 18 - 22 October.

The geomagnetic field was at mostly quiet to unsettled levels during
16 - 21 October. Activity increased to unsettled to active levels
during the latter half of 22 October with storm periods detected at
high latitudes.

Forecast of Solar and Geomagnetic Activity
25 October - 20 November 2000

Solar activity is expected to be at low to moderate levels. Isolated
M-class flares may occur sometime during the period.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit may
reach moderate to high levels beginning 14 November. Otherwise,
normal to moderate fluxes are expected.

Geomagnetic field activity may reach active levels during 18 - 19
November due to coronal hole effects. Otherwise, quiet to unsettled
levels are expected, barring an Earth-directed CME.


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