:Product: 20020422RSGA.txt
:Issued: 2002 Apr 22 2200 UTC
# 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 112 Issued at 2200Z on 22 Apr 2002
IA.  Analysis of Solar Active Regions and Activity from  21/2100Z
to 22/2100Z:  Solar activity decreased to low levels. Region 9906
(S14W103), now well beyond the west limb, produced a C7 X-ray flare
at 22/0019 UTC associated with a bright surge and an eruptive
prominence. Region 9912 (N10W25) produced a C2/Sf flare at 22/1210
UTC associated with a Type II radio sweep (estimated velocity 804
km/sec). Region 9912 was in a gradual growth phase. A weak magnetic
delta configuration may have developed within its trailer spots. New
Region 9917 (S30E45) was numbered.
IB.  Solar Activity Forecast:  Solar activity is expected to be at
low to moderate levels. There's a chance for an isolated M-class
flare from Region 9912.
IIA.  Geophysical Activity Summary 21/2100Z to 22/2100Z:
Geomagnetic field activity ranged from quiet to active levels. Active
levels occurred during 22/0300 - 0600 UTC. The greater than 100 MeV
proton event that began at 21/0155 UTC reached a peak of 22.9 pfu at
21/1025 UTC and was in progress as the period ended. The greater
than 10 MeV proton event that began at 21/0225 UTC reached a peak of
2520 pfu at 21/2320 UTC and was in progress as the period ended.
Peak polar cap absorption associated with the proton event was
estimated to be 16 dB (daytime) and 3.9 dB (nighttime).
IIB.  Geophysical Activity Forecast:  Geomagnetic field activity is
expected to increase to active to minor storm levels on 23 April in
response to yesterday's X1/partial-halo CME event. Unsettled to
active conditions are expected on 24 April as the disturbance winds
down. Unsettled conditions are expected on the final day. The
greater than 100 MeV proton event is expected to end early on 23
April. The greater than 10 MeV proton event is expected to end on 24
April.
III.  Event Probabilities 23 Apr-25 Apr
Class M    40/40/40
Class X    05/05/05
Proton     99/99/20
PCAF       in progress
IV.  Penticton 10.7 cm Flux
Observed           22 Apr 170
Predicted   23 Apr-25 Apr  170/175/175
90 Day Mean        22 Apr 199
V.  Geomagnetic A Indices
Observed Afr/Ap 21 Apr  004/007
Estimated Afr/Ap 22 Apr  013/015
Predicted Afr/Ap 23 Apr-25 Apr  025/030-015/020-015/015
VI.  Geomagnetic Activity Probabilities 23 Apr-25 Apr
A.  Middle Latitudes
Active                40/40/35
Minor storm           20/10/05
Major-severe storm    10/05/05
B.  High Latitudes
Active                50/50/40
Minor storm           30/20/10
Major-severe storm    15/10/01