Viewing archive of Saturday, 20 October 2001

Solar activity report

Report of Solar-Geophysical Activity 2001 Oct 20 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 293 Issued at 2200Z on 20 Oct 2001 ::::::CORRECTED COPY:::::::

IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z

Solar activity was at moderate levels. Region 9658 (S15W73) produced an M3/1f flare at 20/2325 UTC and associated discrete frequency radio bursts. Other activity was centered around Region's 9661 (N15W48) and 9670 (S19E19). Both of these regions produced minor C-class flares though the course of the period. Region 9661 was generally stable and has shown gradual decay as the magnetic delta configuration is no longer apparent in regions spot group. Two new regions were numbered today, Region 9675 (S14E69), and Region 9676 (N13E70).
IB. Solar Activity Forecast
Solar activity is expected to be at moderate to high levels. Region 9661 still remains capable of producing an M-class or isolated major flares.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field was predominantly at quiet to unsettled levels. Brief active conditions were observed at both the middle and high latitudes in the 20/1200-1500 UTC period. The greater than 10 MeV proton flux at geosynchronous orbit passed the 10 pfu threshold at 19/2225 UTC, reached a maximum of 11 pfu at 19/2235 UTC. The short lived 10 MeV proton event ended at 19/2255 UTC though flux levels remained elevated at time of bulletin issue.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at quiet to minor storm levels with the possibility of isolated major storm conditions late on day one and through day two of the period. Analysis of the full halo CME, on LASCO imagery (X1/2b flare at 19/0105 UTC from Region 9661), indicated shock arrival late on day one or early on day two. A second full halo CME (X1/2b flare at 19/1630 UTC from Region 9661) is expected to arrive late on day two of the period. The greater than 10 MeV proton flux levels from geosynchronous orbit could remain elevated through first day of the period.
III. Event Probabilities 21 Oct to 23 Oct
Class M 70%70%70%
Class X 15%15%15%
IV. Penticton 10.7 cm Flux
  Observed       20 Oct 245
  Predicted    21 Oct-23 Oct  245/240/235
  90 Day Mean        20 Oct 190
V. Geomagnetic A Indices
  Observed Afr/Ap 19 Oct  006/008
  Estimated     Afr/Ap 20 Oct  ???/???
  Predicted     Afr/Ap 21 Oct-23 Oct  025/030-030/035-015/025
VI. Geomagnetic Activity Probabilities 21 Oct to 23 Oct
A. Middle Latitudes
Minor storm 30%30%10%
Major-severe storm 05%05%01%
B. High Latitudes
Minor storm 30%30%15%
Major-severe storm 10%10%05%

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