Solar Terrestrial Activity Report [Image] Last update September 17, 2001 at 04:30 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 16. Solar wind speed ranged between 456 and 559 km/sec under the weakening influence of a high speed coronal stream. Solar flare activity was high. Solar flux was 207.1, the planetary A index was 8 (3-hour K indices: 2111 3332, Boulder K indices: 2111 3322). Region 9608 was mostly unchanged and may be capable of producing another major flare. Region 9610 decayed quickly leaving just a few spots by the end of the day. Region 9612 decayed slowly and quietly, the region rotated off the visible disk early today. Region 9616 decayed slowly and has minor M class flaring potential. Region 9617 decayed slowly and quietly. Region 9618 decayed slowly and could become spotless today. Region 9619 decayed slowly and quietly. New regions 9620 and 9621 rotated into view at the northeast limb. Oddly, SEC/NOAA failed to number two other regions in the northeast quadrant, one to the northwest of regions 9620/9621, the other one due west of region 9620. Flares and CMEs A total of 15 C and 1 M class events were observed on September 16. Region 9608 was the source of a major M5.6 flare at 03:53, a C4.5 flare at 06:20, a C2.9 flare at 09:15, a C8.9/1F flare at 13:53, a C3.1 flare at 16:10 and a C4.8 flare at 17:12 UTC. Region 9616 produced a C4.5 flare at 07:45, a C3.5 flare at 18:47 and a C4.1/1F flare at 23:50 UTC. September 14: Region 9616 produced an M3.7 flare at 21:50 UTC. This flare triggered a large filament eruption to the west of the region, possibly producing a CME which could impact Earth on September 17 or 18. The background x-ray flux is at the class C1-C2 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 17, possibly with active intervals late in day as a CME could begin to influence the field. 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 no. Location at region numbered sunspots midnight Area Classification Comment 9608 2001.09.05 15 S29W64 0550 FKI beta-gamma 9610 2001.09.06 14 S12W59 0240 EAO beta-gamma 9612 2001.09.07 2 N17W80 0020 CRO 9615 2001.09.08 N11W42 plage 9616 2001.09.11 29 S12E16 0280 FHI beta-gamma 9617 2001.09.12 4 N13E17 0040 CSO 9618 2001.09.13 4 S21W68 0020 BXO 9619 2001.09.13 7 N17W18 0030 CSO 9620 2001.09.16 3 N12E70 0130 HSX 9621 2001.09.16 1 N16E76 0120 HSX Total number of sunspots: 79 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) 2001.09 223.0 (1) 109.5 (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]