Status Report

NOAA SEC Report of Solar-Geophysical Activity 26 Sep 2001

By SpaceRef Editor
September 26, 2001
Filed under , ,
:Product: Report of Solar-Geophysical Activity
:Issued: 2001 Sep 26 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 269 Issued at 2200Z on 26 Sep 2001
IA.  Analysis of Solar Active Regions and Activity from  25/2100Z
to 26/2100Z:  Solar activity has been moderate. Region 9628 (S18W26)
produced today's only M-class event, an M1 at 0258 UTC. The region
has shown a slight decline and simplification relative to yesterday,
but continues to be the largest on the disk and continues to have
strong, complex magnetic fields. Region 9632 (S19W08) also continues
to be impressive but produced only low-level C-class events. Region
9636 (N13E40) appears to be growing slowly and managed to produce a
couple subflares. New Region 9639 (N04E36) was assigned today and is
a simple beta-type sunspot group.
IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate. There is a fair chance, however,  for an isolated major
flare event or proton producing event from either of Regions 9632 or
IIA.  Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field has ranged from quiet to major storm levels
during the past 24 hours. Following yesterday's sudden storm
commencement at 2025 UTC, the geomagnetic field became disturbed,
and attained major storm levels between 2100-2400 UTC. Conditions
declined slightly from 0000-1200 UTC, with active to minor storm
levels predominating. Activity was quiet to unsettled for the
remainder of the period. The greater than 10 MeV proton event
continues in progress. A maximum flux of 12900 pfu was observed at
25/2235 UTC, after which the flux levels have been steadily
declining. The greater than 100 MeV proton event that began at 
1440 UTC on the 24th attained maximum of 31 PFU at 25/0755 UTC and
ended at 26/1940 UTC.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be mostly unsettled during the next three days. There is
a chance for some active periods during the next 12 hours due to
persistence. Unsettled levels should dominate on the second day.
There is a chance for some active periods on the third day due to
the favorable position of a solar coronal hole. The greater than 10
MeV proton event is expected to continue for the next 42-48 hours.
III.  Event Probabilities 27 Sep-29 Sep
Class M    80/80/80
Class X    30/30/30
Proton     99/90/50
PCAF       in progress
IV.  Penticton 10.7 cm Flux
Observed           26 Sep 283
Predicted   27 Sep-29 Sep  280/275/275
90 Day Mean        26 Sep 171
V.  Geomagnetic A Indices
Observed Afr/Ap 25 Sep  017/018
Estimated Afr/Ap 26 Sep  022/025
Predicted Afr/Ap 27 Sep-29 Sep  015/010-010/010-015/015
VI.  Geomagnetic Activity Probabilities 27 Sep-29 Sep
A.  Middle Latitudes
Active                35/30/35
Minor storm           20/15/25
Major-severe storm    10/05/10
B.  High Latitudes
Active                30/30/30
Minor storm           20/15/30
Major-severe storm    15/05/20

SpaceRef staff editor.