Solar Terrestrial Activity Report [Image] Last update December 21, 2000 at 04:35 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update December 2, 2000) - Has cycle 23 peaked?] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update December 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update December 2, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update October 20, 2000)] Recent development The geomagnetic field was quiet on December 20. Solar wind speed ranged between 312 and 358 km/sec. Solar flare activity was low. Solar flux was 201.3, the planetary A index was 4 (3-hour K indices: 1012 2221, Boulder K indices: 1011 1221). Region 9264 decayed and was quiet. Region 9267 rotated off the visible disk early today. Region 9268 was quiet and stable. Region 9269 decayed slowly, early on Dec.21 the region has only one spot left and could soon become spotless. Region 9272 reemerged with a single spot. Region 9273 was quiet and stable. Region 9278 developed slowly early in the day but seems to have decayed since then. Region 9279 is somewhat unstable and could produce C flares and perhaps a minor M class flare. Region 9280 was mostly quiet but has the potential to produce a major flare. New region 9281 emerged in the northeast quadrant. Flares and CMEs A total of 9 C class events were recorded on December 20. Region 9278 produced a C1.8 flare at 02:10 and a C3.3/1F flare at 05:15 UTC. Region 9279 generated a C2.7 flare at 15:49 UTC. Region 9272 was the source of a C2.6 flare at 19:38 UTC while region 9280 managed a C2.2 flare at 23:03 UTC. A filament eruption was observed in the northern hemisphere near the central meridian starting at 11:48 UTC in LASCO EIT images. This eruption may have caused a geoeffective CME which could influence the geomagnetic field on December 23. December 18: Region 9269 produced a C7.0 flare at 11:11 UTC. The flare was accompanied by a moderate type II sweep and a visually weak and slow full halo coronal mass ejection. With the CME occurring near the center of the solar disk Earth will receive an impact, most likely on December 21. 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 active on December 21-22 with a chance of isolated minor storm intervals. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair. 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 9262 2000.12.08 N16W87 plage 9263 2000.12.09 N18W79 plage 9264 2000.12.10 10 S25W62 0070 DSO 9265 2000.12.10 N19W60 plage 9267 2000.12.11 1 N07W88 0110 HSX 9268 2000.12.13 1 S18W16 0090 HSX 9269 2000.12.13 6 N14W26 0030 CAO 9270 2000.12.13 S10W81 plage 9272 2000.12.14 1 N14W59 0000 AXX 9273 2000.12.15 6 N20E07 0010 BXO 9274 2000.12.16 N16W71 plage 9275 2000.12.16 N22W82 plage 9278 2000.12.17 22 N09E23 0090 DAI 9279 2000.12.18 8 S13E41 0170 FSO 9280 2000.12.19 14 N08E61 0510 DKO beta-gamma 9281 2000.12.20 3 N07E39 0020 CRO Total number of sunspots: 72 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.11 191.5 133.2 111.0 (+3.2) 1999.12 169.8 84.6 111.1 (+0.1) 2000.01 158.1 90.1 112.9 (+1.8) 2000.02 174.1 112.9 116.7 (+3.8) 2000.03 208.2 138.5 119.9 (+3.2) 120.8 (+0.9) 2000.04 184.2 125.5 cycle 23 peak candidate 2000.05 184.9 121.6 119.0 (-1.8) 2000.06 179.8 124.9 (118.3 predicted, -0.7) 2000.07 202.3 169.1 (119.8 predicted, +1.5) 2000.08 163.0 130.5 (120.5 predicted, +0.7) 2000.09 182.1 109.9 (119.6 predicted, -0.9) 2000.10 167.4 100.1 (118.4 predicted, -1.2) 2000.11 178.8 106.5 (116.4 predicted, -2.0) 2000.12 166.6 (1) 89.6 (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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]