Solar Terrestrial Activity Report [Image] Last update September 12, 2000 at 04:15 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update September 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 2, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update August 10, 2000)] Recent development The geomagnetic field was quiet on September 11. Solar wind speed ranged between 329 and 388 km/sec. Solar flare activity was low. Solar flux was 134.9, the planetary A index was 5 (3-hour K indices: 1012 2222, Boulder K indices: 0001 2212). Region 9154 produced a few C flares while at the west limb, the region has now rotated off the visible disk. New region 9161 emerged near the northeast limb. A new region is emerging in the southwest quadrant. The SEC daily sunspot number was only 27, the lowest since February 5, 1999. Flares and CMEs A total of 4 C class event were recorded on September 11. Region 9161 produced a C1.2 flare at 03:13 UTC. Region 9154 generated a C4.2 flare at 07:15 and a C2.0 flare at 09:21 UTC. Region 9158 was the source of a long duration C1.3 event which peaked at 18:13 UTC, a large filament near the region erupted at the same time and may have set off a geoeffective CME. This CME could influence the geomagnetic field on September 14 or 15. September 9: Region 9151 generated an M1.6/1N flare at 08:49 UTC. A moderate type II sweep was recorded as well and a partial halo coronal mass ejection was observed from the north pole to the south pole covering the entire western hemisphere. Parts of this CME could affect Earth on September 12. The background x-ray flux is at the class B4 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled with a chance of active intervals on September 12. Quiet to unsettled is likely on September 13-14. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to poor. Coronal holes (1) Coronal mass M and X class flares (3) ejections (2) [Coronal hole indicator][CME indicator] [M and X class flare indicator] 1) Effects from a coronal hole could reach earth within the next 5 days. 2) Material from a CME is likely to impact earth within 96 hours. 3) There is a possibility of either M or X class flares within the next 48 hours. Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability. Active solar regions (Recent map) Solar Date Actual no. Location at region numbered sunspots midnight Area Classification Comment 9152 20000831 N19W68 plage 9154 20000831 5 S17W91 0120 ESO 9155 20000903 S10W71 plage 9156 20000906 S28W16 plage 9157 20000906 N22W01 plage 9158 20000907 N29E19 plage 9159 20000907 S19W24 plage 9160 20000909 S12W21 plage 9161 20000911 2 N05E52 0010 CRO Total number of sunspots: 7 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.07 165.6 113.5 94.3 (+1.2) 1999.08 170.7 93.7 97.5 (+3.2) 1999.09 135.7 71.5 102.3 (+4.8) 1999.10 164.8 116.7 107.8 (+5.5) 1999.11 191.5 133.2 110.9 (+3.1) 1999.12 169.8 84.6 111.0 (+0.1) 2000.01 158.1 90.1 112.8 (+1.8) 2000.02 174.1 112.9 116.6 (+3.8) 2000.03 208.2 138.5 (118.7 predicted, +2.1) 2000.04 184.2 125.3 (119.6 predicted, +0.9) 2000.05 184.9 120.8 (120.4 predicted, +0.8) 2000.06 179.8 124.9 (122.0 predicted, +1.6) 2000.07 202.3 169.1 (124.1 predicted, +2.1) 2000.08 163.0 130.6 2000.09 159.9 (1) 50.1 (2) 1) Running average based on the daily 20:00 UTC solar flux value at 2800 MHz. 2) Unofficial, accumulated value. The official value is typically 25-40% less. This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]