Report of Solar-Geophysical Activity
Issued: 2005 Sep 08 2200 UTC
Prepared jointly by the U.S. Dept. of Commerce, NOAA, # Space Environment Center and the U.S. Air Force.

Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 251 Issued at 2200Z on 08 Sep 2005 IA. Analysis of Solar Active Regions and Activity from 07/2100Z to 08/2100Z: Solar activity remains at high levels. An X5/2b flare was in progress from Region 808 (S09E67) at the time of this writing. Moderate centimetric radio bursts are also in progress, including a 990 sfu Tenflare. Very active Region 808 is rotating into view as a large and complex sunspot cluster. Limb proximity is still hindering the analysis, but this compact spot group will likely exceed 1000 millionths of white light area. Numerous C-class flares and two M2 flares preceded the X5 event. New Region 809 (N10E60) was numbered today.
IB. Solar Activity Forecast: Solar activity is expected to remain at high levels. Region 808 is a large and complex sunspot group capable of producing M and X-class flares.
IIA. Geophysical Activity Summary 07/2100Z to 08/2100Z:
The geomagnetic field was quiet to unsettled. A sudden disturbance of 41 nT (magnetic crochet) was observed in the geomagnetic field following today's X5 flare. A greater than 10 and greater than 100 MeV proton event occurred following yesterday's X17 flare on the southeast limb. The greater than 10 MeV proton event began at 08/0215Z and remains in progress. The peak flux so far was 87 pfu at 08/1950Z. The greater than 100 MeV proton event began at 08/0405Z and also remains in progress. The peak flux was 7 pfu at 08/1925Z.
A greater than 100 MeV proton event from a source on the east limb is extremely rare. The greater than 2 MeV electron flux at geosynchronous orbit was at high levels again today.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected to range from quiet to minor storm levels. The CME associated with yesterday's X17 flare was very large and very fast.
Although the magnetic cloud associated with this CME is not expected to impact Earth, a shock passage is expected, which will likely produce active to minor storm periods on 09 Sep. Isolated active periods are expected on 10 and 11 Sep. The greater than 10 MeV proton event currently in progress is expected to continue through 10 Sep. A further enhancement in the greater than 10 MeV protons will likely follow the anticipated shock passage on 09 Sep. Today's
X5 flare may enhance the existing proton event. The greater than 100 MeV proton event will persist through 09 Sep.
III. Event Probabilities 09 Sep-11 Sep
Class M 80/80/80
Class X 50/50/50
Proton 99/90/75
PCAF in progress
IV. Penticton 10.7 cm Flux
Observed 08 Sep 094
Predicted 09 Sep-11 Sep 100/110/110
90 Day Mean 08 Sep 091
V. Geomagnetic A Indices
Observed Afr/Ap 07 Sep 018/015
Estimated Afr/Ap 08 Sep 008/012
Predicted Afr/Ap 09 Sep-11 Sep 020/025-015/020-008/010 VI. Geomagnetic Activity Probabilities 09 Sep-11 Sep A. Middle Latitudes
Active 40/30/25
Minor storm 20/15/10
Major-severe storm 10/05/01
B. High Latitudes
Active 50/40/30
Minor storm 30/20/15
Major-severe storm 15/10/05