Viewing archive of Tuesday, 25 September 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 Sep 25 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 268 Issued at 2200Z on 25 Sep 2001

IA. Analysis of Solar Active Regions and Activity from 24-2100Z to 25-2100Z

Solar activity was high. Region 9628 (S18W14) produced an M7/1n with associated Type II sweep at 0440 UTC. In addition, the region also generated an M2/1n with Type II at 1027 UTC, and an M1/Sf at 0148 UTC. This region was the premier flare site of the day as Region 9632 (S19E06), the site of the X2/2b flare of 24/1038 UTC, was unproductive. There are fifteen spotted regions visible today, with new region 9638 (N03E61), the most recent addition.
IB. Solar Activity Forecast
Solar activity is expected to be moderate to high. Both Regions 9628 and 9632 retain the potential for additional M-class activity, and a possible isolated X-class event.
IIA. Geophysical Activity Summary 24-2100Z to 25-2100Z
The geomagnetic field was quiet until the end of the interval. A shock, presumably related to the flare/CME of 24/1038 UTC, passed ACE at approximately 2003 UTC. A sudden impulse then occurred at Boulder at 2025 UTC, measuring 25 nT. The field is now at active levels. The proton events at greater than 10 and 100 MeV continue. The tentative peak flux for the greater than 10 MeV event is 5040 pfu at 2100 UTC. The greater than 100 MeV tentative max was 31 pfu at 0755 UTC. The Polar Cap Absorption event remains in progress.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at major storm levels during the next 24-36 hours, due to the effects of a shock/cme related to the X2/2b flare of 24/1038 UTC. The storm should persist through 27 September. The current proton events are expected to continue for at least the next 24 hours.
III. Event Probabilities 26 Sep to 28 Sep
Class M80%80%80%
Class X30%30%30%
PCAFin progress
IV. Penticton 10.7 cm Flux
  Observed       25 Sep 275
  Predicted   26 Sep-28 Sep  270/265/260
  90 Day Mean        25 Sep 169
V. Geomagnetic A Indices
  Observed Afr/Ap 24 Sep  005/006
  Estimated     Afr/Ap 25 Sep  010/012
  Predicted    Afr/Ap 26 Sep-28 Sep  080/100-040/040-015/015
VI. Geomagnetic Activity Probabilities 26 Sep to 28 Sep
A. Middle Latitudes
Minor storm25%50%60%
Major-severe storm65%25%15%
B. High Latitudes
Minor storm25%40%60%
Major-severe storm70%40%20%

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