Viewing archive of Thursday, 4 April 2002

Solar activity report

Report of Solar-Geophysical Activity 2002 Apr 04 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 094 Issued at 2200Z on 04 Apr 2002

IA. Analysis of Solar Active Regions and Activity from 03-2100Z to 04-2100Z

Solar activity increased to high levels, due to an impulsive M6.1 flare at 04/1532 UTC, which originated from a source region behind the southeast limb. The presumed source is old Region 9866 (S09, L=191), which was an active flare producer on its last rotation, and is expected to rotate back into view within 24 hours. Other activity included an impulsive M1.4 flare at 04/1048 UTC from an evident source behind the southwest limb, and a C9.8 flare at 04/0442 UTC from a spotless plage region near S20E58, which was accompanied by a Type-II radio sweep (estimated velocity = 463 km/s) and a nearby disappearing filament. The CME activity associated with these events did not appear Earth-directed in SOHO/LASCO imagery. Most numbered regions on the visible disk appeared little changed from yesterday. Minor optical flares were observed in Regions 9885 (N13W39), 9888 (S12W06), and 9893 (N18E64).
IB. Solar Activity Forecast
Solar activity is expected to be predominantly low to moderate for the next three days. A chance for isolated major flare activity exists, in particular with the return of old Region 9866.
IIA. Geophysical Activity Summary 03-2100Z to 04-2100Z
The geomagnetic field was quiet to unsettled. At 04/1335 UTC, the greater than 2 MeV electron flux exceeded event threshold at GOES-8 in geosynchronous orbit (75W). Flux levels remained above 1000 pfu for the remainder of the period.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be predominantly quiet to unsettled. A chance for some isolated active periods exists for days two and three of the forecast period, due to the possibility of some flanking shock passage effects from the CME events observed earlier today. Greater than 2 MeV electron flux is expected to persist at moderate to high levels for the next two to three days.
III. Event Probabilities 05 Apr to 07 Apr
Class M60%60%60%
Class X05%05%05%
IV. Penticton 10.7 cm Flux
  Observed       04 Apr 216
  Predicted   05 Apr-07 Apr  215/215/210
  90 Day Mean        04 Apr 203
V. Geomagnetic A Indices
  Observed Afr/Ap 03 Apr  012/013
  Estimated     Afr/Ap 04 Apr  008/012
  Predicted    Afr/Ap 05 Apr-07 Apr  008/010-012/012-010/010
VI. Geomagnetic Activity Probabilities 05 Apr to 07 Apr
A. Middle Latitudes
Minor storm05%05%05%
Major-severe storm01%01%01%
B. High Latitudes
Minor storm05%05%05%
Major-severe storm01%01%01%

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