Solar Terrestrial Activity Report [Image] Last update December 24, 2001 at 03:20 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 unsettled on December 23. Solar wind speed ranged between 329 and 408 km/sec. A weak solar wind shock was observed at ACE at 22:21 UTC. Solar flare activity was moderate. Solar flux was 254.6, the planetary A index was 7 (3-hour K indices: 2123 2223, Boulder K indices: 2123 2323). Region 9742 developed quickly, particularly in the intermediate spot section where penumbral area increase was dramatic. Negative and positive magnetic areas are not well separated any more and magnetic gradients are tightening along a generally north-south inversion line. The potential for a major flare is increasing, even X class flares are possible. Region 9743 was quiet and stable. Region 9745 was quiet and stable. Region 9747 decayed slowly and quietly. Region 9748 was the most active region and could produce further M class flares. Region 9750 rotated quietly off the visible disk. Region 9751 developed slowly and could produce minor M class flares. Region 9752 was spotless early in the day, then reemerged with a few spots. Region 9753 was quiet and stable. New region 9754 emerged quickly near the southeast limb and is already capable of producing M class flares. Flares and CMEs A total of 7 C and 1 M class events were recorded on 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), a C3.1 flare at 08:16 and a long duration M1.2 event peaking at 23:36 UTC. Region 9754 produced an impulsive M1.7 flare at 00:32 UTC on December 24. 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 unsettled on December 24-26. 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 9738 2001.12.12 S17W67 plage 9740 2001.12.13 S06W75 plage 9741 2001.12.13 N04W70 plage 9742 2001.12.15 55 N10W29 0900 FKC beta-gamma 9743 2001.12.16 2 S11W20 0120 CSO 9744 2001.12.16 S05W68 plage 9745 2001.12.18 10 N17W07 0070 DAO 9746 2001.12.19 S17W45 plage 9747 2001.12.19 5 N11E17 0050 DSO 9748 2001.12.20 19 S10W07 0200 DAO beta-gamma 9749 2001.12.20 S08E30 plage 9750 2001.12.21 2 S16W86 0050 DRO 9751 2001.12.21 14 N04E44 0320 EKO 9752 2001.12.22 4 S14W31 0020 DSO 9753 2001.12.22 3 S20E53 0060 CAO 9754 2001.12.23 6 S09E61 0090 EAO Total number of sunspots: 120 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 (108.5 predicted, -0.2) 2001.07 131.3 82.2 (108.1 predicted, -0.4) 2001.08 162.9 106.8 (108.7 predicted, +0.6) 2001.09 233.2 150.7 (108.1 predicted, -0.6) 2001.10 207.6 125.6 (105.3 predicted, -2.8) 2001.11 210.6 106.5 (103.7 predicted, -1.6) 2001.12 225.8 (1) 156.5 (2) (100.3 predicted, -3.4) 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]