Status Report

NOAA SEC Report of Solar-Geophysical Activity 30 Sep 2001

By SpaceRef Editor
September 30, 2001
Filed under , ,
:Product: Report of Solar-Geophysical Activity
:Issued: 2001 Sep 30 2200 UT
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
#Space Environment Center and the U.S. Air Force.
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 273 Issued at 2200Z on 30 Sep 2001
IA.  Analysis of Solar Active Regions and Activity from  29/2100Z
to 30/2100Z:  Solar activity remained at moderate levels. Region 9628
(S17W76) produced a long-duration M1/Sf flare at 30/1141 UTC
associated with minor discrete frequency radio emission. Region 9628
may have decayed a bit as it approached the west limb, but remained
large and complex. Decay was also noted in Region 9632 (S18W61) as
its large interior spot mass began to split, which may have
dissipated the magnetic delta structure contained therein.
Nonetheless, this region remained large and complex. Region 9636
(N14W15), a reverse-polarity sunspot group, showed gradual
development during the day. It was moderate in size and complexity
as it produced isolated subflares, none of which were associated
with significant X-ray or radio emission.
IB.  Solar Activity Forecast:  Solar activity is expected to remain
at moderate levels. Isolated M-class flares will be possible from
Regions 9628, 9632, and 9636. Regions 9628 and 9632 each could
produce an isolated major flare before they rotate out of view on 01
and 02 October, respectively.
IIA.  Geophysical Activity Summary 29/2100Z to 30/2100Z:
Geomagnetic field activity ranged from quiet to minor storm levels.
Minor storm levels occurred globally during 29/2100 - 2400 UTC
following a sustained period of southward IMF Bz (as measured by
NASA's ACE spacecraft). Activity decreased to quiet to unsettled
levels during 30/0000 - 1500 UTC, then increased to active levels
for the rest of the period. An interplanetary shock passed the ACE
spacecraft at 30/1848 UTC. The source for this shock may have been a
CME that followed a long-duration M3/2n flare from Region 9636 at
28/0830 UTC. The greater than 10 MeV event that began at 24/1215 UTC
ended at 30/1710 UTC.
IIB.  Geophysical Activity Forecast:  Active geomagnetic conditions
will be possible during 01 - 02 October due to recent CME activity.
Field activity is expected to decrease to quiet to unsettled levels
on 03 October. There will be a slight chance for a proton flare from
Region 9628 or 9632 during the period.
III.  Event Probabilities 01 Oct-03 Oct
Class M    80/75/70
Class X    25/20/10
Proton     20/15/10
PCAF       yellow
IV.  Penticton 10.7 cm Flux
Observed           30 Sep 236
Predicted   01 Oct-03 Oct  230/225/225
90 Day Mean        30 Sep 176
V.  Geomagnetic A Indices
Observed Afr/Ap 29 Sep  019/021
Estimated Afr/Ap 30 Sep  012/012
Predicted Afr/Ap 01 Oct-03 Oct  020/015-015/012-012/012
VI.  Geomagnetic Activity Probabilities 01 Oct-03 Oct
A.  Middle Latitudes
Active                40/40/30
Minor storm           20/20/10
Major-severe storm    10/10/01
B.  High Latitudes
Active                50/50/35
Minor storm           25/25/15
Major-severe storm    15/15/01

SpaceRef staff editor.