Joint USAF/NOAA Report of Solar and Geophysical Activity 17 Jan 2005

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Updated 2005 Jan 17 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 017 Issued at 2200Z on 17 Jan 2005

IA. Analysis of Solar Active Regions and Activity from 16/2100Z
to 17/2100Z: Solar activity was high. Region 720 (N13W30) continued
to produce flare activity with the largest being an X3/2f at 17/0952
UTC. This flare was associated with a complex full-halo CME directed
mostly towards the northwest. Although this region remains large and
magnetically complex some restructuring of the sunspots was apparent
following this flare. New Region 723 (N06E77) is rotating around the
east limb.

IB. Solar Activity Forecast: Solar activity is expected to remain
at high to very high levels. Region 720 could produce yet another
major solar event.

IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field ranged from quiet to severe storm levels. Solar
wind conditions observed by the NASA ACE spacecraft show a fairly
complex onset of activity which may suggest the arrival of a solar
wind structure from combined CMEs expected from previous major
flares on 15 January. The proton event at greater than 10 MeV that
began on 16/0210 UTC remains in progress. The latest X3 flare
discussed in Part IA has increased the current peak flux to 5040 pfu
observed at 17/1750 UTC. A proton event at greater than 100 MeV also
resulted from the X3 flare, beginning at 17/1215 UTC and with a
current peak flux of 28 pfu observed at 17/1700 UTC. The greater
than 2 MeV electron flux observed by the GOES spacecraft, as well as
the solar wind parameters observed by the ACE SWEPAM instruments,
have been rendered temporarily unusable due to the energetic proton
event.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to continue at major to severe storm levels. Another CME
arrival is expected late on 18 January, or possibly early on 19
January, due to today’s X3 flare, which should keep geomagnetic
activity levels elevated. The current proton events are expected to
remain in progress.

III. Event Probabilities 18 Jan-20 Jan

• Class M 90/90/90
• Class X 30/30/30
• Proton 99/99/99
• PCAF in progress

IV. Penticton 10.7 cm Flux

• Observed 17 Jan 138
• Predicted 18 Jan-20 Jan 135/130/120
• 90 Day Mean 17 Jan 107

V. Geomagnetic A Indices

• Observed Afr/Ap 16 Jan 010/012
• Estimated Afr/Ap 17 Jan 060/080
• Predicted Afr/Ap 18 Jan-20 Jan 060/080-050/050-030/030

VI. Geomagnetic Activity Probabilities 18 Jan-20 Jan

A. Middle Latitudes

• Active 15/20/50
• Minor storm 50/50/30
• Major-severe storm 35/30/10

B. High Latitudes

• Active 10/10/50
• Minor storm 50/50/30
• Major-severe storm 40/40/20