NOAA SEC Report of Solar-Geophysical Activity 20 May 2001
:Product: Report of Solar-Geophysical Activity :Issued: 2001 May 20 2300 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 140 Issued at 2200Z on 20 May 2001 IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was high. Two highly impulsive M-class flares occurred during the period. Both were optically uncorrelated. The first was an M6 flare at 20/0603 UTC, with an accompanying Type II radio sweep (1200 km/s) and a 360 sfu 10 cm radio burst. EIT imagery shows that this event originated over the southwestern limb and was probably from Region 9455 (S17W90+). An impressive coronal mass ejection (CME) in conjunction with the flare can be seen on images from the LASCO/SOHO spacecraft. The CME appears to be non earth-directed. An M1 flare with an accompanying Type II radio sweep (1088 km/s) was detected at 20/0920 UTC. This event was most likely a backside event from the same region as the previously described M6 event. Region 9463 (N09E46) nearly doubled in size and spot count overnight and also developed into a more complex sunspot group classification (14 spot, Eko-Beta). Region 9465 (S08E63) was numbered as it rotated onto the disk, already showing a 4 spot Dao-Beta sunspot classification. IB. Solar Activity Forecast: Solar activity is expected to be low to moderate. Regions 9461 (N22E10) and 9463 are both capable of producing isolated M-class events. IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field was at quiet to unsettled levels. The greater than 10 MeV proton flux at geosynchronous orbit became enhanced following today's M6 flare, but did not reach event criteria. The greater than 2 MeV electron flux at geosynchronous orbit reached moderate levels during the period. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be mostly quiet to unsettled for the first two days of the forecast period. Isolated active conditions may occur on the third day due to a potentially favorably positioned coronal hole and the subsequent high speed stream impacting earth. The greater than 2 MeV electron flux and greater than 10 MeV proton flux at geosynchronous orbit should continue to be at elevated levels for the first half of the period and then can expected to return to near background levels. III. Event Probabilities 21 May-23 May Class M 30/30/30 Class X 01/01/01 Proton 01/01/01 PCAF green IV. Penticton 10.7 cm Flux Observed 20 May 142 Predicted 21 May-23 May 140/140/140 90 Day Mean 20 May 168 V. Geomagnetic A Indices Observed Afr/Ap 19 May 010/012 Estimated Afr/Ap 20 May 008/012 Predicted Afr/Ap 21 May-23 May 008/012-008/012-015/015 VI. Geomagnetic Activity Probabilities 21 May-23 May A. Middle Latitudes Active 20/20/25 Minor storm 05/05/10 Major-severe storm 01/01/01 B. High Latitudes Active 25/25/35 Minor storm 10/10/15 Major-severe storm 01/01/01
