:Product: Weekly Highlights and Forecasts
:Issued: 2001 Sep 11 2112 UT
Highlights of Solar and Geomagnetic Activity
03 - 09 September 2001

Solar activity ranged from from low to high levels. However, the
predominate condition was moderate with high levels observed on 05
and 09 September due to major solar flares (for flare specifics,
please refer to the Energetic Events list). Region 9601 (N13, L=214,
class/area Eki/830 on 05 September) produced the first major flare,
an impulsive M6/2b at 05/1432 UTC associated with a 800 sfu
Tenflare. Region 9601 also produced isolated, low-level M-class
flares during the period including an M1/1f at 07/1538 UTC
associated Type II and IV radio sweeps. This large, magnetically
complex sunspot group rotated out of view at the close of the
period. Region 9608 (S26, L=111, class/area Fkc/1050 on 09
September) produced the other major flare of the period, an
impulsive M9/2n flare at 09/2045 UTC associated with a 510 sfu
Tenflare. Region 9608 developed multiple magnetic delta
configurations within its interior spots prior to the M9 flare. This
region also produced isolated, low-level M-class flares during the
rest of the period as it remained large and magnetically complex.
Region 9591 (S19, L=295, class/area Fki/740 on 25 August), which
produced a major flare on 25 August, was large, magnetically complex
and in a gradual decay phase as it rotated out of view on 04
September. Regions 9606 (S17, L=151, class/area Eki/360 on 06
September) and 9607 (S16, L=126, class/area Eai/300 on 08 September)
produced isolated, low-level M-class flares during the period. Both
regions were moderate in size and complexity.

Solar Wind data were available from the Advanced Composition Explorer
(ACE) spacecraft for most of the period.

There were no proton events detected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels through 30 August, then decreased to
normal levels for the rest of the period.

The geomagnetic field was disturbed on 27 August following a sudden
impulse at 27/1952 UTC (37 nT, as measured by the Boulder USGS
magnetometer). Active periods occurred during this disturbance. A
few active periods also occurred during 30 - 31 August, possibly due
to a CME passage. Quiet to unsettled levels prevailed during the
remainder of the period.

Forecast of Solar and Geomagnetic Activity
12 September - 08 October 2001

Solar activity is expected to be at low to moderate levels. Isolated
M-class flares are possible. There will be a chance for a major
flare until Region 9601 departs the west limb on 10 September.

There will be a chance for a solar proton event from Region 9601
until it departs the west limb.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at normal to moderate levels during most of the
period.

Active geomagnetic field conditions will be possible around 18 and 30
September due to coronal hole effects. Otherwise, quiet to unsettled
levels are expected.


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