Solar Terrestrial Activity Report [Image] Last update September 18, 2000 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 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 severe storm on September 17. Solar wind speed ranged between 410 and 877 km/sec. A new disturbance was observed at ACE at 15:40 UTC (probable origin one of the halo CMEs observed on September 15). Solar wind speed increased quickly between 17 and 19h UTC to nearly 800 km/sec, then decreased fairly quickly before increasing again after 21h UTC (this may have been the arrival of the second halo CME observed on September 15, or possibly even the larger and faster halo CME observed on September 16). Early on September 18 solar wind speed exceeded 900 km/sec, just below the highest value recorded this solar cycle. The interplanetary magnetic field was at times exceptionally strongly southwards following the arrival of the CMEs and the planetary A index for the final 3 hours of the day was 160. Solar flare activity was low. Solar flux was 181.5, the planetary A index was 40 (3-hour K indices: 4423 4457, Boulder K indices: 4422 4446). Region 9161 was quiet and stable, as was region 9164. Region 9165 decayed slowly but seems to have developed a weak magnetic delta. M class flares are possible. Region 9166 developed slowly and may have a weak magnetic delta configuration, the region is capable of M class flaring. Region 9167 developed slowly as it rotated fully into view. New region 9168 emerged in the northeast quadrant near the central meridian. A new and interesting region with a very large penumbra is rotating into view at the northeast limb very near region 9166. M class flares appear to be possible from this region. Flares and CMEs A total of 13 C class events were recorded on September 17. Region 9165 produced a C3.8 flare at 00:42, a C2.9 flare at 05:16, a C3.1 flare at 05:38, a C2.2 flare at 16:41 and a C1.6 flare at 18:25 UTC. Region 9166 generated a C1.5 flare at 02:00 UTC. Region 9167 was the source of a C1.6 flare at 04:49, a C5.4/1F flare at 06:38 and a C3.4 flare at 21:03 UTC. September 16: Region 9165 produced a major M5.9/2B long duration event peaking at 04:26 (associated with a moderate type II sweep and a strong type IV sweep as well as a full halo CME). The background x-ray flux is at the class C1 level. Coronal holes A coronal hole in the southern hemisphere was in a possibly geoeffective position on September 16-17. Forecast The geomagnetic field is expected to be unsettled to severe storm on September 18. Quiet to active is likely on September 19-20. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is useless. 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 9157 20000906 N22W79 plage 9158 20000907 N31W61 plage 9161 20000911 9 N06W28 0070 DAO 9163 20000912 S17W75 plage 9164 20000913 5 S13W69 0030 CSO 9165 20000913 32 N14W26 0230 DAI beta-gamma-delta 9166 20000914 32 S14E37 0340 EAI beta-gamma-delta 9167 20000916 5 N11E69 0170 DSO 9168 20000917 3 N09E06 0010 CSO Total number of sunspots: 86 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 (118.7 predicted, +2.1) 2000.04 184.2 125.3 (119.6 predicted, +0.9) 2000.05 184.9 120.8 (120.4 predicted, +0.8) 2000.06 179.8 124.9 (122.0 predicted, +1.6) 2000.07 202.3 169.1 (124.1 predicted, +2.1) 2000.08 163.0 130.6 2000.09 158.4 (1) 71.8 (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]