Viewing archive of Friday, 17 August 2001

Solar activity report

Report of Solar-Geophysical Activity 2001 Aug 17 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 229 Issued at 2200Z on 17 Aug 2001

IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z

Solar activity was low. Only a few low-level C-class subflares occurred. The largest was a C1/Sf at 17/0011 UTC in Region 9581 (S25W42). Although there are several sunspot groups on the visible disk all of them are relatively small and magnetically simple. New Regions 9586 (S15W47) and 9587 (S11E56) were numbered.
IB. Solar Activity Forecast
Solar activity is expected to be low. Additional low-level C-class flares are possible.
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
The geomagnetic field was quiet until the occurrence of a sudden impulse observed at ground magnetometers (36 nT at Boulder) at about 17/1103 UTC. The impulse was preceded by a shock observed at the NASA ACE spacecraft at 17/1017 UTC. The geomagnetic field has been at mostly active to minor storm levels since the impulse. A series of magnetopause crossings were observed at the NOAA GOES spacecraft in the interval from about 17/1930--2100 UTC. The greater than 100 MeV proton event which began yesterday has ended (start 16/0105 UTC, 29 pfu peak at 16/0305 UTC, and end 17/1415 UTC). The greater than 10 MeV event remains in progress (start 16/0135 UTC and 493 pfu peak at 16/0355 UTC). The current proton flux (17/2100 UTC) at greater than 10 MeV is about 20 pfu and is slowly decaying.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at mostly active to minor storm levels for the next 24 hours becoming unsettled to active after that. The greater than 10 MeV proton event is expected to end by 19 August.
III. Event Probabilities 18 Aug to 20 Aug
Class M10%10%10%
Class X01%01%01%
PCAFin progress
IV. Penticton 10.7 cm Flux
  Observed       17 Aug 145
  Predicted   18 Aug-20 Aug  150/150/155
  90 Day Mean        17 Aug 151
V. Geomagnetic A Indices
  Observed Afr/Ap 16 Aug  003/008
  Estimated     Afr/Ap 17 Aug  025/025
  Predicted    Afr/Ap 18 Aug-20 Aug  020/015-015/015-010/018
VI. Geomagnetic Activity Probabilities 18 Aug to 20 Aug
A. Middle Latitudes
Minor storm15%05%05%
Major-severe storm05%01%01%
B. High Latitudes
Minor storm20%10%05%
Major-severe storm05%01%01%

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