Solar Terrestrial Activity Report [Image] Last update September 16, 2001 at 05:35 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 15. Solar wind speed ranged between 448 and 597 km/sec under the influence of a high speed coronal stream. Solar flare activity was moderate. Solar flux was 219.3, the planetary A index was 15 (3-hour K indices: 3223 4433, Boulder K indices: 3322 4333). Region 9607 decayed quietly and rotated out of view early on September 16. Region 9608 decayed losing much of its areal coverage and quite a few spots. A magnetic delta configuration emerged in a penumbra just west of the main penumbra. Major flares are possible. Region 9610 decayed further and was quiet. The region has a decreasing chance of producing a minor M class flare. Region 9612 decayed further and had only a few spots left by the end of the day. Region 9616 decayed significantly but could still produce occasional M class flares. Region 9617 decayed slowly and quietly. Region 9618 was quiet and stable, as was region 9619. A new region is rotating into view at the northeast limb and may be capable of producing minor M class flares. An interesting region is approaching the southeast limb. Flares and CMEs A total of 5 C and 2 M class events were observed on September 15. Region 9608 produced an M1.5/1N long duration event peaking at 11:28 UTC. This event was associated with a weak type II radio sweep and resulted in a marginal proton event with the above 10 MeV proton flux peaking at 11 pfu. Region 9608 was the source of a C8.8 flare at 20:33 UTC. Region 9616 generated an M1.3 flare at 15:59 UTC. Region 9608 was the source of a major M5.6 flare at 03:53 UTC on September 16. There was no immediate increase in protons near Earth and the event does not appear to have been a significant particle event. 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 A coronal hole in the northern hemisphere was in a geoeffective position on September 12-14. Forecast The geomagnetic field is expected to be quiet to unsettled on September 16-17, possibly with active intervals late on the second day as a CME could begin influencing 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 Location region numbered no. at Area Classification Comment sunspots midnight 9607 2001.09.04 2 S17W78 0060 HSX area too high 9608 2001.09.05 20 S28W54 0620 FKI beta-gamma-delta 9610 2001.09.06 24 S13W46 0430 EKI beta-gamma area way too high! 9612 2001.09.07 10 N20W68 0110 DAO Too many spots! Embarrassing error by SEC/NOAA! 9615 2001.09.08 N11W29 plage 9616 2001.09.11 26 S12E30 0320 FAI beta-gamma 9617 2001.09.12 7 N08E30 0060 DSO 9618 2001.09.13 6 S20W53 0060 DRO 9619 2001.09.13 8 N16W06 0040 DSO Total number of sunspots: 103 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) 2001.09 224.1 (1) 103.9 (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]