Solar Terrestrial Activity Report [Image] Last update December 25, 2001 at 04:55 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update December 2, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update December 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update December 2, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update October 16, 2001)] Recent development The geomagnetic field was quiet to minor storm on December 24. Solar wind speed ranged between 348 and 617 km/sec. A coronal stream arrived one day later than expected and disturbed the geomagnetic field, particularly after 06h UTC when a strong southerly excursion of the interplanetary magnetic field was observed at ACE. Solar flare activity was moderate. Solar flux was 274.5 (with several developing regions solar flux could soon reach the highest level recorded during solar cycle 23, there is even a possibility that the average monthly solar flux (cycle high) from September could be overtaken in December), the planetary A index was 19 (3-hour K indices: 3354 4432, Boulder K indices: 2354 4322). Region 9742 developed further and there is little separating the positive leader spots from the negative intermediate spots, actually a magnetic delta may already have formed. A major flare is possible today or tomorrow. Region 9743 was quiet and stable, as was region 9745. Region 9747 decayed slowly and quietly. Region 9748 developed further and a magnetic delta could develop in the trailing spots section. M class flares are likely. Region 9751 developed slowly and could produce minor M class flares. Region 9752 once again decayed into spotless plage. Region 9753 developed slowly and quietly. Region 9754 developed further and may have a weak magnetic delta at the southern edge of the leading spots section. A new region rotated into view at the northeast limb but did not make it into SEC/NOAAs spots summary. Flares and CMEs A total of 3 C and 3 M class events were recorded on December 24. Region 9754 produced an impulsive M1.7/1N flare at 00:32 and an M1.4/1F flare at 22:41 UTC. Region 9742 generated a C3.3 flare at 03:04 UTC, while region 9748 managed a C4.4 flare at 08:05 UTC. An M3.5 flare at 14:00 UTC was optically uncorrelated, LASCO C2 images indicate this event may have occurred near the east limb. December 23: Region 9748 produced a C4.9 flare at 03:57. A weak geoeffective CME may have been associated with this event, a coronal wave was observed in EIT images. The background x-ray flux is at the class 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 December 25-26. 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 9738 2001.12.12 S17W80 plage 9740 2001.12.13 S06W88 plage 9741 2001.12.13 N04W83 plage 9742 2001.12.15 40 N11W44 0960 FKC beta-gamma 9743 2001.12.16 2 S10W34 0090 CAO 9744 2001.12.16 S05W81 plage 9745 2001.12.18 9 N17W22 0030 DAO 9746 2001.12.19 S17W58 plage 9747 2001.12.19 5 N12E02 0020 DSO 9748 2001.12.20 13 S10W21 0180 EAO beta-gamma 9749 2001.12.20 S08E17 plage 9751 2001.12.21 13 N05E30 0380 EKO 9752 2001.12.22 S14W44 plage 9753 2001.12.22 8 S18E37 0080 CAO 9754 2001.12.23 6 S08E48 0080 EAO beta-gamma Total number of sunspots: 96 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.8 2000.10 167.4 99.4 114.5 (-1.8) 2000.11 178.8 106.8 112.7 (-1.8) 2000.12 173.6 104.4 112.0 (-0.7) 2001.01 166.6 95.6 108.7 (-3.3) 2001.02 146.6 80.6 104.1 (-4.6) 2001.03 177.7 113.5 104.8 (+0.7) 2001.04 177.7 107.7 107.6 (+2.8) 2001.05 147.1 96.6 108.7 (+1.1) 2001.06 173.0 134.0 (109.3 predicted, +0.6) 2001.07 131.3 82.2 (109.8 predicted, +0.5) 2001.08 162.9 106.8 (110.3 predicted, +0.5) 2001.09 233.2 150.7 (109.7 predicted, -0.6) 2001.10 207.6 125.6 (107.0 predicted, -2.7) 2001.11 210.6 106.5 (105.3 predicted, -1.7) 2001.12 227.8 (1) 162.2 (2) (102.0 predicted, -3.3) 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]