Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Jan 2005

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2005 Jan 20 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 020 Issued at 2200Z on 20 Jan 2005

IA. Analysis of Solar Active Regions and Activity from 19/2100Z
to 20/2100Z: Solar activity was high. Region 720 (N14W70) produced
an X7/2b flare at 0701 UTC, which was accompanied by Type II and
Type IV radio sweeps. There is one image from the LASCO C2
coronagraph which shows an associated CME off the northwest limb at
0654 UTC. However, shortly after this observation the coronagraph
data became difficult to use due to high levels of energetic
particles. Region 720 continues to be large, with a sheared magnetic
delta configuration along an east-west polarity inversion line.

IB. Solar Activity Forecast: Solar activity is expected to be
moderate to high. Region 720 continues to have potential for
producing an additional major flare. The location of Region 720 on
the disk also implies that there is a fair chance for more energetic
particles in association with future major flare activity.

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field was quiet to active during the past 24 hours.
Solar wind speeds were elevated (700-900 km/s) from the start of the
interval up through at least 0700 UTC, after which the ACE real-time
SWEPAM data became unusable due to elevated energetic particle
flux. The interplanetary magnetic field, however, was weak with
fluctuations between -4 nT to +6 nT. A new injection of protons was
observed at 0650 UTC in association with the X7 flare. The greater
than 100 MeV protons rose rapidly and attained a maximum of 652 PFU
at 0710 UTC. The 100 MeV flux has been declining steadily since
then. This high flux level makes this the largest greater than 100
MeV proton event observed since October 1989. A greater than 10 MeV
proton event was in progress at the time of the new injection, but
the new particles quickly increased the flux from initial values
around 40 PFU to a peak value in the past 24 hours of 1860 PFU at
0810 UTC.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be predominantly unsettled to active for the next three
days. Today’s CME (associated with the X7 flare) is not expected to
produce anything more than a glancing blow due to its direction away
from the Sun-Earth line. The greater than 10 MeV flux is expected
to remain above event threshold for at least another 24 hours.

III. Event Probabilities 21 Jan-23 Jan

• Class M 90/90/80
• Class X 30/30/20
• Proton 99/80/50
• PCAF in progress

IV. Penticton 10.7 cm Flux

• Observed 20 Jan 123
• Predicted 21 Jan-23 Jan 115/105/095
• 90 Day Mean 20 Jan 108

V. Geomagnetic A Indices

• Observed Afr/Ap 19 Jan 031/062
• Estimated Afr/Ap 20 Jan 012/015
• Predicted Afr/Ap 21 Jan-23 Jan 015/025-015/020-010/020

VI. Geomagnetic Activity Probabilities 21 Jan-23 Jan

A. Middle Latitudes

• Active 35/35/20
• Minor storm 20/20/15
• Major-severe storm 15/15/05

B. High Latitudes

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