Joint USAF/NOAA Report of Solar and Geophysical Activity 21 Sep 2007

Product: Report of Solar-Geophysical Activity
Issued: 2007 Sep 21 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 264 Issued at 2200Z on 21 Sep 2007

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity was very low. The visible disk remained spotless.

IB. Solar Activity Forecast: Solar activity is expected to remain very low.

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field was unsettled at the beginning of the period but quickly subsided to quiet levels. Real-time solar wind observations from ACE show a gradual increase in wind speed consistent with the onset of a coronal hole-high speed stream. However, Bz has been mostly northwards resulting in very little geomagnetic response at this time.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to become unsettled to active on 22-23 September, with a chance for minor storm periods at high latitudes, as the influence of the coronal hole increases. Activity is expected to subside to unsettled levels on 24 September.

III. Event Probabilities 22 Sep-24 Sep

• Class M 01/01/01
• Class X 01/01/01
• Proton 01/01/01
• PCAF green

IV. Penticton 10.7 cm Flux

• Observed 21 Sep 067
• Predicted 22 Sep-24 Sep 067/067/067
• 90 Day Mean 21 Sep 070

V. Geomagnetic A Indices

• Observed Afr/Ap 20 Sep 006/010
• Estimated Afr/Ap 21 Sep 008/008
• Predicted Afr/Ap 22 Sep-24 Sep 015/015-015/015-010/010

VI. Geomagnetic Activity Probabilities 22 Sep-24 Sep

A. Middle Latitudes

• Active 35/35/15
• Minor storm 10/10/10
• Major-severe storm 10/10/05

B. High Latitudes

• Active 35/30/25
• Minor storm 15/15/10
• Major-severe storm 10/10/05