Solar Terrestrial Activity Report [Image] Last update September 3, 2000 at 05:20 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 unsettled to minor storm on September 2. Solar wind speed ranged between 406 and 581 km/sec, early on under the influence of a coronal stream, then with what was probably the effects from a CME observed late on August 28 dominating the solar wind. Solar flare activity was low. Solar flux was 154.0, the planetary A index was 23 (3-hour K indices: 4345 4333, Boulder K indices: 4445 4433). Region 9140 was quiet and stable, the region is rotating off the visible disk. Region 9142 was quiet and stable. Region 9143 decayed slowly and was quiet. Region 9144 was quiet and rotated over the west limb. Region 9145 was quiet and stable. Region 9146 reemerged with a single spot. Region 9147 decayed slowly and was quiet. Region 9149 was quiet and stable. Occasional C class flares are likely and there is a possibility of a minor M class flare. Region 9150 was quiet and stable, as were regions 9151, 9152 and 9153. Flares and CMEs Only 1 C class event was recorded on September 2. It was a long duration C2.3 event which peaked at 03:40 UTC. The source of the event was a filament eruption to the south and southwest of region 9148. September 1: Region 9143 was at the center of a long duration C1.6 event peaking at 06:06 UTC. A filament eruption and an accompanying almost full coronal mass ejection was observed. The CME was visible all around the solar disk except off the northern part of the northeast limb. A terrestrial impact is possible on September 4. Region 9140 produced the largest x-ray event of the day, a C9.1/1N flare. A moderate type II sweep occurred in connection with the flare, however, a CME from this event near the northwest limb is unlikely to influence Earth. The background x-ray flux is at the class B5 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions.. Forecast The geomagnetic field is expected to be quiet to unsettled on September 3. Quiet to minor storm is possible on September 4. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very 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 9140 20000822 6 N09W82 0100 DAO 9142 20000824 1 N16W45 0010 HSX 9143 20000824 2 S19W47 0050 DSO 9144 20000825 1 N24W91 0050 HSX 9145 20000827 7 S10W21 0040 CAO 9146 20000827 1 S24W31 0010 AXX 9147 20000828 3 N05E01 0090 CSO 9148 20000828 S18W20 plage 9149 20000828 25 N12E06 0350 EKI 9150 20000830 1 N12E25 0000 AXX 9151 20000831 4 N06E15 0010 BXO 9152 20000831 1 N18E47 0040 HSX 9153 20000831 5 S33E03 0010 BXO 9154 20000831 S21E31 plage Total number of sunspots: 57 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 (120.1 predicted, +3.5) 2000.04 184.2 125.3 (122.5 predicted, +2.4) 2000.05 184.9 120.8 (123.4 predicted, +0.9) 2000.06 179.8 124.9 (124.9 predicted, +1.5) 2000.07 202.3 169.1 (127.0 predicted, +2.1) 2000.08 163.0 130.6 2000.09 155.9 (1) 12.4 (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]