Solar Terrestrial Activity Report [Image] Last update September 5, 2000 at 04:10 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 to minor storm on September 4. Solar wind speed ranged between 410 and 502 km/sec. A weak solar wind shock was observed at 12:45 UTC at ACE. Solar wind speed increased abruptly from 450 to 500 km/sec. The source of this disturbance is likely a partial halo CME observed on September 1. Solar flare activity was moderate. Solar flux was 170.8, the planetary A index was 14 (3-hour K indices: 1122 2454, Boulder K indices: 1022 3233). Region 9142 decayed into spotless plage. Region 9143 decayed slowly and was quiet, the region is spotless early on September 5. Region 9145 decayed slowly and was quiet. Region 9146 decayed into spotless plage. Region 9147 decayed slowly and was quiet. Region 9149 was mostly unchanged and will likely produce occasional C class flares. A minor M class flare is possible. Regions 9151, 9152 and 9153 were quiet and stable. Region 9154 continued to develop quickly. The region has a magnetic delta configuration and will likely produce frequent C flares and occasional M class flares. Region 9155 was quiet and stable. Flares and CMEs A total of 15 C and 1 M class event were recorded on September 4. Region 9154 produced an M1.3/1N flare at 01:09, a C1.5 flare at 06:52, a C2.2 flare at 14:18, a C2.0 flare at 20:16, a C2.1 flare at 20:46 and a C4.9 flare at 21:35 UTC. Region 9149 generated a C1.6 flare at 11:38, a C1.3 flare at 12:51, a C2.9 flare at 14:54, a C2.7 flare at 16:38 and a C3.3 flare at 17:50 UTC. A large filament eruption occurred in the northwest quadrant at approximately 05-06h UTC. Unfortunately LASCO movies have not been updated for a couple of days, and it is therefore difficult to state with any degree of certainty that the associated CME will influence the geomagnetic field on September 7. A CME was observed off the northwest limb in single LASCO images. The background x-ray flux is at the class C1 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 5-6. 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 Location region numbered no. at Area Classification Comment sunspots midnight 9142 20000824 N16W76 plage 9143 20000824 1 S19W75 0000 AXX 9145 20000827 1 S08W50 0030 HSX 9146 20000827 S23W58 plage 9147 20000828 4 N08W22 0060 CAO 9148 20000828 S18W46 plage 9149 20000828 27 N14W22 0220 EAI beta-gamma 9150 20000830 N12W01 plage 9151 20000831 3 N09W09 0010 BXO 9152 20000831 1 N18E22 0020 HSX 9153 20000831 8 S32W23 0020 CSO 9154 20000831 27 S19E06 0160 DAI beta-gamma-delta 9155 20000903 7 S10E18 0020 BXO Total number of sunspots: 79 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 2000.09 159.2 (1) 24.1 (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]