NOAA SEC Report of Solar-Geophysical Activity 16 Aug 2001

:Product: Report of Solar-Geophysical Activity
:Issued: 2001 Aug 16 2300 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 228 Issued at 2200Z on 16 Aug 2001
IA.  Analysis of Solar Active Regions and Activity from  15/2100Z
to 16/2100Z:  Solar activity from numbered regions on the visible
disk was low.  Impulsive B- and C-class flares were observed
throughout the period, the largest being an optically uncorrelated
C3 flare at 16/0957 UTC.  However, the most impressive activity of
the day was a remarkable backside CME, observed on SOHO/LASCO
starting at about 15/2355 UTC.  This event resulted in the proton
enhancements discussed in section IIA below.  The observed CME
together with backside imagery inferred from the SOHO/MDI instrument
suggest old Region 9557 (S20, L=283) as the likely source, presently
located near the far backside central meridian.  On the visible
disk, three new regions were numbered today:  9583 (S23E13), 9584
(S11E60), and 9585 (N15E74).  All appear to be small, simply
structured beta-class groups with low flare activity potential.
IB.  Solar Activity Forecast:  Solar activity on the visible disk is
expected to persist at mainly low levels for the next three days.
IIA.  Geophysical Activity Summary 15/2100Z to 16/2100Z:
Geomagnetic field activity has been quiet to unsettled throughout the
period.  A major proton event for >= 100MeV protons above 1pfu began
at 16/0105 UTC, followed by >= 10Mev protons above 10pfu at 16/0135
UTC.  Maximum flux for 100Mev protons was 29pfu at 16/0305 UTC, and
for 10MeV protons was 493pfu at 16/0355 UTC.  Both events remain in
progress, and represent a record response for a presumed CME source
so far behind the western limb as described in section 1A above. 
Greater than 2MeV electrons were observed at moderate enhancement
levels again today, although the electron sensor on GOES-8 was
saturated by the proton event for much of the period.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at active to minor storm levels within 24 hours, in
response to anticipated shock passage from CME activity reported on
August 14th.  Isolated major storm periods may also be possible at
higher latitudes, as well as an enhancement of 10MeV proton levels
for the event in progress.  Geomagnetic storm activity is expected
to wane during day two, along with the 100MeV proton event.  The
10MeV proton event is expected to persist at levels above 10pfu into
day three.  Greater than 2MeV electrons are also expected to persist
at moderate enhancement levels.
III.  Event Probabilities 17 Aug-19 Aug
Class M    25/25/25
Class X    01/01/01
Proton     99/95/90
PCAF       red
IV.  Penticton 10.7 cm Flux
Observed           16 Aug 143
Predicted   17 Aug-19 Aug  140/140/145
90 Day Mean        16 Aug 151
V.  Geomagnetic A Indices
Observed Afr/Ap 15 Aug  004/009
Estimated Afr/Ap 16 Aug  007/008
Predicted Afr/Ap 17 Aug-19 Aug  025/020-017/015-012/018
VI.  Geomagnetic Activity Probabilities 17 Aug-19 Aug
A.  Middle Latitudes
Active                35/30/25
Minor storm           20/15/10
Major-severe storm    10/05/05
B.  High Latitudes
Active                40/30/30
Minor storm           20/15/15
Major-severe storm    05/05/05