Joint USAF/NOAA Report of Solar and Geophysical Activity 20 Jul 2004
Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2004 Jul 20 2210 UTC
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 202 Issued at 2200Z on 20 Jul 2004
IA. Analysis of Solar Active Regions and Activity from 19/2100Z
to 20/2100Z: Solar activity increased to high levels today. Region
652 (N10E32) produced an M8/3b major flare at 20/1232Z with an
associated Tenflare of 3000 sfu’s. A Type II radio sweep with an
estimated shock velocity of 485 km/s and a Type IV also accompanied
the flare. The C6/Sf flare that occurred at 20/1126Z in conjunction
with the flare mentioned above produced what appears as a full halo
CME signature on LASCO C3 imagery. The delta structure seen as the
dominate intermediate spot remains intact and the magnetic
classification continues to exhibit beta-gamma-delta properties.
Region 652 continues to show growth in spot area which now exceeds
1600 millionths in white light. Region 649 (S10W27) continues to
show decay and was limited to C-class flare activity today. Delta
structures are evident in the leading polarity spot cluster while
yesterday’s trailing polarity delta spot is no longer discernible.
A significant and continued loss of spot area was again seen over
the past 24 hours. No new regions were numbered today.
IB. Solar Activity Forecast: Solar activity is expected to be at
moderate to high levels. Region 652 is capable of producing further
major flare activity.
IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field was at quiet to unsettled levels.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at predominantly unsettled levels on 21 and 22 July.
A shock passage from the combination of the C6 and M8 x-ray flares
today is expected to pass the ACE spacecraft early on 23 July.
III. Event Probabilities 21 Jul-23 Jul
- Class M 75/75/75
- Class X 30/30/30
- Proton 15/20/25
- PCAF green
IV. Penticton 10.7 cm Flux
- Observed 20 Jul 175
- Predicted 21 Jul-23 Jul 180/175/170
- 90 Day Mean 20 Jul 098
V. Geomagnetic A Indices
- Observed Afr/Ap 19 Jul 011/009
- Estimated Afr/Ap 20 Jul 008/008
- Predicted Afr/Ap 21 Jul-23 Jul 008/008-010/012-025/025
VI. Geomagnetic Activity Probabilities 21 Jul-23 Jul
A. Middle Latitudes
- Active 15/15/40
- Minor storm 05/10/25
- Major-severe storm 01/05/15
B. High Latitudes
- Active 15/20/45
- Minor storm 05/15/25
- Major-severe storm 01/05/15
