Solar Terrestrial Activity Report [Image] Last update September 12, 2001 at 03:45 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 1, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 1, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 1, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update July 27, 2001)] Recent development The geomagnetic field was quiet to active on September 11. Solar wind speed ranged between 274 and 440 km/sec. A coronal stream began to influence the field before noon. Solar flare activity was moderate. Solar flux was 249.7, the planetary A index was 9 (3-hour K indices: 1001 3433, Boulder K indices: 1211 4433). Region 9606 decayed quickly leaving only a few spots. Region 9607 decayed further and was quiet. Region 9608 decayed slowly leaving only one magnetic delta configuration within the huge main penumbra. A major X class flare is possible. Region 9610 developed slowly and could produce M class flares. Region 9611 was mostly unchanged and quiet, the region will be rotating onto the northwest limb today. Region 9612 developed slowly and quietly. New region 9616 rotated partly into view at the southeast limb and appears to be capable of producing major flares. Another active region should soon be rotating into view at the northeast limb. Flares and CMEs A total of 8 C and 3 M class events were observed on September 11. Region 9608 produced a C3.9 flare at 00:17, a C9.5 flare at 00:33 and an M2.6 flare at 01:11 UTC. Region 9616 generated an M1.2 flare at 07:04 and an M4.5 flare at 20:36 UTC. Region 9610 was the source of a C4.8 flare at 22:35 UTC. September 9: A strong type II radio sweep was observed in association with the M3/M2 flares in regions 9607 and 9608 from 15:17 UTC. LASCO C3 images indicate that a CME was produced. Although most of the ejected material was observed above the east limb, this may have been a full halo CME. The background x-ray flux is at the class C2 level. Coronal holes A coronal hole in the northern hemisphere will rotate into a geoeffective position on September 12. Forecast The geomagnetic field is expected to be unsettled to minor storm on September 12-13 due to a coronal stream and a possible CME impact. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 9603 2001.09.02 S08W55 plage 9605 2001.09.03 S19W58 plage 9606 2001.09.03 3 S19W50 0150 CAO 9607 2001.09.04 9 S17W24 0150 EAO 9608 2001.09.05 44 S27W07 1030 FKI beta-gamma-delta 9610 2001.09.06 37 S14E08 0540 EKI beta-gamma 9611 2001.09.07 6 N09W76 0390 DKO 9612 2001.09.07 10 N22W13 0080 DAO 9614 2001.09.08 N15W60 plage 9615 2001.09.08 N11E23 plage 9616 2001.09.11 1 S12E80 0040 HAX Total number of sunspots: 110 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.03 208.2 138.5 119.9 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.7 2000.08 163.0 130.5 118.6 (-1.1) 2000.09 182.1 109.7 116.3 (-2.3) 2000.10 167.4 99.4 114.5 (-1.8) 2000.11 178.8 106.8 112.8 (-1.7) 2000.12 173.6 104.4 112.1 (-0.7) 2001.01 166.6 95.6 108.8 (-3.3) 2001.02 146.6 80.6 104.1 (-4.7) 2001.03 177.7 113.5 (103.8 predicted, -0.3) 2001.04 177.7 108.2 (104.1 predicted, +0.3) 2001.05 147.1 97.3 (102.6 predicted, -1.5) 2001.06 173.0 134.0 (99.8 predicted, -2.8) 2001.07 131.3 82.2 (98.0 predicted, -1.8) 2001.08 162.9 106.8 (98.5 predicted, +0.5) 2001.09 220.9 (1) 75.5 (2) (97.5 predicted, -1.0) 1) Running average based on the daily 20:00 UT solar flux value at 2800 MHz. 2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number 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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]