Viewing archive of Thursday, 19 April 2001
Solar activity report
Any mentioned solar flare in this report has a scaling factor applied by the Space Weather Prediction Center (SWPC). Because of the SWPC scaling factor, solar flares are reported as 42% smaller than for the science quality data. The scaling factor has been removed from our archived solar flare data to reflect the true physical units.
Report of Solar-Geophysical Activity 2001 Apr 19 2200 UTC
Prepared by the NOAA © SWPC and processed by SpaceWeatherLive.comJoint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 109 Issued at 2200Z on 19 Apr 2001
IA. Analysis of Solar Active Regions and Activity from 18-2100Z to 19-2100Z
Solar activity was moderate due to an M2 x-ray flare at
19/1135 UTC. An optical flare report was not received but SOHO/EIT
difference images suggest the source was Region 9433 (N17E64), the
return of old 9393. All of this region appears to have rotated onto
the disk and is presently seen as a moderately-sized (700
millionths) F-type sunspot group with some mixed polarities. This
area also produced a few small C-class subflares during the day.
Interestingly, a CME was visible entering the SOHO/LASCO/C2 field of
view over the northwest limb shortly after the M2 at about 19/1200
UTC. The location suggests that departed Region 9415 was involved
with this activity but any connection to the M2 discussed above may
only be coincidental. Regions 9434 (N19W23) and 9435 (S21E28) were
numbered.
IB. Solar Activity Forecast
Solar activity is expected to be low
to moderate. Region 9433 is expected to continue to produce C-class
flares and appears capable of additional M-class activity.
IIA. Geophysical Activity Summary 18-2100Z to 19-2100Z
The geomagnetic field has been quiet to unsettled. The greater than
100 MeV proton event ended at 19/0325 UTC (start 18/0315 UTC, 12 pfu
peak at 18/0600 UTC). The polar cap absorption (PCA) event has also
ended (19/1400 UTC). The greater than 10 MeV proton event continues
in progress (start 18/0315 UTC, 321 pfu peak at 18/1045 UTC, and
current flux about 15 pfu at 19/2100 UTC) and is slowly decaying.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to continue at quiet to unsettled levels. The greater than
10 MeV proton event is expected to drop below event threshold
sometime tomorrow (April 20 UTC).
III. Event Probabilities 20 Apr to 22 Apr
Class M | 50% | 50% | 50% |
Class X | 05% | 05% | 05% |
Proton | 95% | 01% | 01% |
PCAF | green
|
IV. Penticton 10.7 cm Flux
Observed 19 Apr 145
Predicted 20 Apr-22 Apr 155/165/175
90 Day Mean 19 Apr 165
V. Geomagnetic A Indices
Observed Afr/Ap 18 Apr 022/050
Estimated Afr/Ap 19 Apr 010/008
Predicted Afr/Ap 20 Apr-22 Apr 010/010-010/010-010/010
VI. Geomagnetic Activity Probabilities 20 Apr to 22 Apr
A. Middle Latitudes |
Active | 10% | 10% | 10% |
Minor storm | 05% | 05% | 05% |
Major-severe storm | 01% | 01% | 01% |
B. High Latitudes |
Active | 15% | 15% | 15% |
Minor storm | 10% | 10% | 10% |
Major-severe storm | 01% | 01% | 01% |
All times in UTC
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