Solar Terrestrial Activity Report [Image] Last update December 22, 2001 at 03:30 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 active on December 21. Solar wind speed ranged between 340 and 469 km/sec. An unexpected disturbance arrived at noon and was in progress until the end of the day. The disturbance has been weakening slowly since about 18h UTC on Dec.21. Solar flare activity was low. Solar flux was 234.3, the planetary A index was 11 (3-hour K indices: 1222 3443, Boulder K indices: 0222 2442). Region 9737 reemerged with a single spot before rotating over the southwest limb. Region 9738 decayed and was spotless by midnight. Region 9742 developed further with most of the development taking place due north of the leading penumbra. A magnetic delta could be developing in the south of the region. A major flare is possible. Region 9743 was quiet and stable. Region 9745 decayed slowly and was quiet. Region 9746 reemerged briefly with a few spots, the region appears to be spotless early on Dec.22. Region 9747 was quiet and stable. Region 9748 is developing slowly (with spots emerging mostly in a straight line) and has mixed polarities. Region 9749 was mostly quiet and stable. New region 9750 emerged near the southwest limb. New region 9751 rotated into view at the northeast limb. Flares and CMEs A total of 6 C class events were recorded on December 21. Region 9742 produced a C3.5 flare at 00:29, a C3.1 flare at 03:28, a C4.0 flare at 05:21, a C3.1 flare at 10:08 and a C3.1 flare at 13:41 UTC. The background x-ray flux is at the class C1-C2 level. Coronal holes An isolated coronal hole in the southern hemisphere may have been in a geoeffective position on December 20. Forecast The geomagnetic field is expected to be quiet to unsettled on December 22. There is a chance of a minor coronal stream based disturbance on December 23, unsettled to active conditions are possible. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to 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 region numbered sunspots at Area Classification Comment midnight 9734 2001.12.09 S16W75 plage 9737 2001.12.10 1 S29W83 0010 HSX 9738 2001.12.12 2 S17W51 0010 BXO now spotless 9740 2001.12.13 S06W49 plage 9741 2001.12.13 N05W34 plage 9742 2001.12.15 60 N10W03 0720 FKC beta-gamma 9743 2001.12.16 5 S10E04 0130 CAO 9744 2001.12.16 S05W42 plage 9745 2001.12.18 6 N17E19 0020 CRO 9746 2001.12.19 3 S17W20 0010 BXO now spotless 9747 2001.12.19 11 N12E44 0060 CAO 9748 2001.12.20 8 S12E21 0050 DAO beta-gamma 9749 2001.12.20 5 S08E56 0060 CSO 9750 2001.12.21 3 S16W64 0030 DSO 9751 2001.12.21 1 N04E68 0220 HAX Total number of sunspots: 105 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) 2001.12 223.6 (1) 141.9 (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]