Viewing archive of Saturday, 20 April 2002
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 2002 Apr 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 110 Issued at 2200Z on 20 Apr 2002IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z Solar activity was low during the past 24 hours. Most
of today's activity consisted of occasional C-class flares. The
largest of these was a C4/Sf from Region 9912 at 1548 UTC. Region
9912 showed significant growth during the past 24 hours and is a
D-type sunspot region. Region 9906 (S14W79) continues to be the
largest group on the disk and is beginning to cross the west limb.
IB. Solar Activity Forecast
Solar activity is expected to be
mostly low, but there is a chance for an isolated M-class event
sometime during the next three days.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field was at active to major storm levels at
mid-latitudes and was active to severe storm at high latitudes. The
peak of the magnetic storm occurred from 0000-0900 UTC in
association with strong transient solar wind flow. The level of
geomagnetic activity weakened to mostly active during the last nine
hours, consistent with the slow return of solar wind flow to nominal
levels.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be unsettled to active during the next 24 hours as the
current disturbance subsides. Conditions should be mostly unsettled
by the second day, and quiet to unsettled by the third day. There is
a possibility for enhancement of greater than 2 MeV electrons during
the next 24-36 hours due to the current high solar wind speeds.
III. Event Probabilities 21 Apr to 23 Apr
| Class M | 35% | 30% | 25% |
| Class X | 05% | 05% | 05% |
| Proton | 05% | 05% | 05% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 20 Apr 177 Predicted 21 Apr-23 Apr 170/170/170 90 Day Mean 20 Apr 200
V. Geomagnetic A Indices
Observed Afr/Ap 19 Apr 036/044 Estimated Afr/Ap 20 Apr 040/060 Predicted Afr/Ap 21 Apr-23 Apr 015/020-010/010-007/008
VI. Geomagnetic Activity Probabilities 21 Apr to 23 Apr
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 45% | 25% | 20% |
| Minor storm | 20% | 20% | 20% |
| Major-severe storm | 15% | 05% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 45% | 30% | 25% |
| Minor storm | 20% | 20% | 20% |
| Major-severe storm | 20% | 10% | 10% |
All times in UTC
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