NOAA SEC Report of Solar-Geophysical Activity 24 Nov 2001
:Product: Report of Solar-Geophysical Activity :Issued: 2001 Nov 24 2210 UT # 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 328 Issued at 2200Z on 24 Nov 2001 IA. Analysis of Solar Active Regions and Activity from 23/2100Z to 24/2100Z: Solar activity was low. Region 9704 (S17W63) was the principle source of flare activity and produced numerous C-class flares, the largest being a C7/Sf at 24/0553 UTC. No new regions were numbered. IB. Solar Activity Forecast: Solar activity is expected to be predominantly low to moderate. Region 9704 remains a potential source for an isolated major flare with associated proton enhancements, as it rotates through the geoeffective heliographic longitudes over the next two days. IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z: Geomagnetic field activity ranged from quiet to severe storm levels. The onset of storm conditions began with two sudden impulse observations: 20nt at 24/0500 UTC, followed by 80nt at 24/0555 UTC. The shock passages enhanced the already high 10 MeV proton integral flux to a peak value of 18900 pfu at 24/0555 UTC. Severe storm conditions were evident in planetary K-index values during 24/0600-1800 UTC. This event is the likely result of interaction among up to three interplanetary shock propagations from separate CME events during 21-23 November, indicated by re-analysis of shock arrival model predictions with improved event velocity data. Results suggest that the CMEs may have merged into the single interplanetary shock that passed the earth today. The 10 MeV proton event and associated polar cap absorption remained in progress at the end of the period, however the 100 MeV proton event ended at 24/1200 UTC. IIB. Geophysical Activity Forecast: Geomagnetic field activity may persist with isolated active and minor storm conditions for the next 48 hours, in the wake of today's shock passage. Conditions are expected to return to quiet to unsettled conditions by day three. The 10 MeV proton event is expected to continue to wane over the next 24 hours. III. Event Probabilities 25 Nov-27 Nov Class M 40/40/40 Class X 10/10/10 Proton 95/50/10 PCAF in progress IV. Penticton 10.7 cm Flux Observed 24 Nov 173 Predicted 25 Nov-27 Nov 170/170/175 90 Day Mean 24 Nov 218 V. Geomagnetic A Indices Observed Afr/Ap 23 Nov 011/012 Estimated Afr/Ap 24 Nov 095/105 Predicted Afr/Ap 25 Nov-27 Nov 030/030-018/020-012/010 VI. Geomagnetic Activity Probabilities 25 Nov-27 Nov A. Middle Latitudes Active 35/25/20 Minor storm 20/10/05 Major-severe storm 05/05/01 B. High Latitudes Active 35/30/20 Minor storm 25/15/05 Major-severe storm 10/05/01
