Joint USAF/NOAA Report of Solar and Geophysical Activity 18 Sep 2002
Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 261 Issued at 2200Z on 18 Sep 2002 IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity was low with several minor C-class flares observed throughout the period. Region 119 (S14E04) exhibited considerable growth and was responsible for majority of the C-class flares. Renewed complexity developed in Region 105 (S09W70) and occasional C-class flares were observed. White light areal coverage still exceeds 500 millionths in this moderately complex beta-gamma region. Active Region 114 (S11W57) showed significant decay over the last 24 hours. New Regions 124 (N03W49) and 125 (S08E69) were numbered today. IB. Solar Activity Forecast: Solar activity is expected to be low to moderate. Best chance for an isolated M-class flare is from developing Region 119 or Region 105 as it approaches the west limb. IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field was mostly quiet to unsettled with isolated active periods. The disturbed conditions are due to the elevated solar wind speed (550 km/s). IIB. Geophysical Activity Forecast: The geomagnetic field is expected to continue at mostly unsettled levels with isolated active periods. Active to minor storm conditions are expected on the latter half of day one due to the C8 flare and partial halo CME that occurred early on 17 Sep. Expect conditions to return to unsettled levels as the expected storm subsides on day two. III. Event Probabilities 19 Sep-21 Sep Class M 40/40/40 Class X 05/05/05 Proton 05/05/05 PCAF green IV. Penticton 10.7 cm Flux Observed 18 Sep 177 Predicted 19 Sep-21 Sep 175/165/160 90 Day Mean 18 Sep 178 V. Geomagnetic A Indices Observed Afr/Ap 17 Sep 011/013 Estimated Afr/Ap 18 Sep 013/014 Predicted Afr/Ap 19 Sep-21 Sep 015/020-015/015-008/012 VI. Geomagnetic Activity Probabilities 19 Sep-21 Sep A. Middle Latitudes Active 45/45/25 Minor storm 25/25/10 Major-severe storm 10/10/05 B. High Latitudes Active 50/50/30 Minor storm 30/30/10 Major-severe storm 20/20/05
