Viewing archive of Sunday, 23 September 2001

Solar activity report

Report of Solar-Geophysical Activity 2001 Sep 23 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 266 Issued at 2200Z on 23 Sep 2001

IA. Analysis of Solar Active Regions and Activity from 22-2100Z to 23-2100Z

Solar activity was moderate. Region 9632 (S18E32) produced an M1/Sn flare at 1137 UTC, the day's only M-class event. That region is still large -- 780 millionths in white light area -- and magnetically complex. Other regions of note are 9622 (N13W45) and 9628 (S18E12). One new region was born on the disk, Region 9635 (N22E13), a simple bipole.
IB. Solar Activity Forecast
Solar activity is expected to persist at the moderate level.
IIA. Geophysical Activity Summary 22-2100Z to 23-2100Z
The geomagnetic field varied from quiet to minor storm levels in the past 24 hours. A shock passed the ACE spacecraft at about 0800 UTC, followed by an increase in solar wind radial speed to near 600 km/s. Periods of active to minor storm levels resulted from this fast solar wind.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be unsettled to active throughout the forecast period. The current high speed solar wind stream may persist over the next few days, bringing occasional episodes of minor storm conditions to all latitudes.
III. Event Probabilities 24 Sep to 26 Sep
Class M70%70%70%
Class X10%10%10%
IV. Penticton 10.7 cm Flux
  Observed       23 Sep 259
  Predicted   24 Sep-26 Sep  265/270/270
  90 Day Mean        23 Sep 167
V. Geomagnetic A Indices
  Observed Afr/Ap 22 Sep  006/010
  Estimated     Afr/Ap 23 Sep  015/020
  Predicted    Afr/Ap 24 Sep-26 Sep  010/012-010/018-010/020
VI. Geomagnetic Activity Probabilities 24 Sep to 26 Sep
A. Middle Latitudes
Minor storm10%10%10%
Major-severe storm01%01%01%
B. High Latitudes
Minor storm15%15%15%
Major-severe storm05%05%05%

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