Solar Terrestrial Activity Report [Image] Last update September 3, 2001 at 03:55 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 unsettled on September 2. Solar wind speed ranged between 326 and 405 km/sec. What is likely a weak coronal stream began to influence the field late in the day. Solar flare activity was moderate. Solar flux was 182.5, the planetary A index was 7 (3-hour K indices: 1002 3333, Boulder K indices: 1001 3432). Region 9591 developed slowly during the first half of the day but decayed again following the M3 flare. A major flare is still possible as the region is rotating onto the southwest limb. Region 9596 was quiet and stable. Region 9599 decayed slowly and quietly. Region 9601 was mostly unchanged and has major flare potential. Region 9602 was quiet and stable. New region 9603 rotated into view at the southeast limb. Oddly, SEC/NOAA failed to number two new regions which were visible by noon, one region in the southwest quadrant and to the north of region 9599, the other one in the southeast quadrant due south of region 9603. Another region appears to be about to rotate into view at the southeast limb. Flares and CMEs A total of 11 C and 3 M class events were observed on September 2. Region 9601 produced a C4.9 flare at 04:40, an M1.1 flare at 06:24, a C3.3 flare at 13:15 and a C3.6 flare at 15:17 UTC. Region 9591 generated a C2.7 flare at 05:08, an M1.3/1F flare at 06:02, a C4.7 flare at 12:08 and an impulsive M3.0/2N flare at 13:46 UTC. 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 3, possibly with a few active intervals. 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 9591 2001.08.21 15 S18W65 0340 EKO beta-gamma-delta 9596 2001.08.25 1 N22W23 0160 HSX 9597 2001.08.26 N19W41 plage 9599 2001.08.27 7 S18W14 0100 DAO 9601 2001.08.27 51 N14E08 0700 EKC gamma 9602 2001.09.01 6 S08E18 0020 BXO 9603 2001.09.02 1 S08E64 0040 HSX Total number of sunspots: 81 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 (102.2 predicted, -1.9) 2001.04 177.7 108.2 (101.2 predicted, -1.0) 2001.05 147.1 97.3 (100.1 predicted, -1.1) 2001.06 173.0 134.0 (97.3 predicted, -2.8) 2001.07 131.3 82.2 (95.5 predicted, -1.8) 2001.08 162.9 106.8 (96.0 predicted, +0.5) 2001.09 183.3 (1) 9.8 (2) (95.0 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]