NOAA SEC Report of Solar-Geophysical Activity 28 Dec 2001

:Product: Report of Solar-Geophysical Activity
:Issued: 2001 Dec 28 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 362 Issued at 2200Z on 28 Dec 2001
IA.  Analysis of Solar Active Regions and Activity from  27/2100Z
to 28/2100Z:  Solar activity was high.  An X3.4 flare from an
apparent east limb source occurred at 28/2045 UTC, and remained in
progress at the end of the period.  This event was accompanied by
bright loops visible in h-alpha imagery behind the east limb near
S27.  A fainter prominence was also visible on the northwest limb
near the approximate location of Region 9742 (N12W94), but the lack
of subsequent energetic particle enhancements seems to favor the
east limb source.  Other activity included an impulsive M4/Sf from
Region 9742 at 28/0351 UTC, and weaker M-class events from Regions
9748 (S11W76) and 9754 (S08W02).  Two new regions were numbered
today:  9764 (N12E15) and 9765 (N05E77).
IB.  Solar Activity Forecast:  Solar activity is expected to remain
moderate to high for the next three days.
IIA.  Geophysical Activity Summary 27/2100Z to 28/2100Z:
The geomagnetic field was quiet to unsettled.  The greater than 10
MeV proton event which had been in progress since 26 December ended
today.  The event began at 26/0605 UTC, reached a maximum flux of
779 pfu at 26/1115 UTC, and ended at 28/1040 UTC.
IIB.  Geophysical Activity Forecast:  The increase in geomagnetic
field activity, which had been expected for today, has not yet
occurred, but precursors in solar wind data from the ACE satellite
suggest that a shock arrival may still yet occur, perhaps within the
next 10 hours or so.  Uncertainty in the earthward speed of shock
propagation from the CME event of 26 December is a likely cause for
the delay, though this event could also miss the Earth.  Unsettled
to minor storm conditions, and isolated major storms conditions at
higher latitudes, remain possible within the first day of the
forecast period.  Predominantly quiet to unsettled conditions are
expected thereafter.
III.  Event Probabilities 29 Dec-31 Dec
Class M    75/75/75
Class X    10/10/10
Proton     10/10/10
PCAF       red
IV.  Penticton 10.7 cm Flux
Observed           28 Dec 263
Predicted   29 Dec-31 Dec  260/255/255
90 Day Mean        28 Dec 218
V.  Geomagnetic A Indices
Observed Afr/Ap 27 Dec  010/006
Estimated Afr/Ap 28 Dec  012/010
Predicted Afr/Ap 29 Dec-31 Dec  025/030-012/015-008/010
VI.  Geomagnetic Activity Probabilities 29 Dec-31 Dec
A.  Middle Latitudes
Active                30/20/15
Minor storm           20/05/05
Major-severe storm    05/01/01
B.  High Latitudes
Active                35/25/15
Minor storm           25/10/05
Major-severe storm    10/05/01