Solar Terrestrial Activity Report [Image] Last update December 21, 2001 at 03:25 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 slightly unsettled on December 20. Solar wind speed ranged between 343 and 417 km/sec. Solar flare activity was low. Solar flux was 221.1, the planetary A index was 5 (3-hour K indices: 1012 2321, Boulder K indices: 0022 2331). Region 9733 decayed slowly and rotated off the visible disk. Region 9738 decayed quietly. Region 9741 decayed and is spotless early on Dec.21. Region 9742 developed quickly, particularly in the northeastern part where new positive magnetic flux is emerging in or near predominantly negative magnetic areas. The potential for a major flare has increased significantly. Region 9743 was quiet and stable. Region 9745 was quiet and stable, as was region 9747. New region 9748 emerged in the southeast quadrant. New region 9749 rotated into view at the southeast limb. A new region is rotating into view at the northeast limb. Flares and CMEs A total of 6 C class events were recorded on December 20. Region 9742 produced a C8.7 flare at 04:38, a C4.4 flare at 15:26, a C2.7 flare at 17:15 and a C5.0 flare at 18:12 UTC. Region 9741 generated a C3.1 flare at 08:47 UTC. The background x-ray flux is at the class C1 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 21-22. 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. 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 9733 2001.12.08 3 N12W85 0070 CAO 9734 2001.12.09 S16W62 plage 9737 2001.12.10 S27W78 plage 9738 2001.12.12 3 S18W34 0020 CRO 9740 2001.12.13 S06W36 plage 9741 2001.12.13 5 N05W21 0010 BXO now spotless 9742 2001.12.15 45 N10E13 0530 EKI beta-gamma 9743 2001.12.16 5 S11E19 0120 CAO 9744 2001.12.16 S05W29 plage 9745 2001.12.18 8 N17E33 0030 BXO 9746 2001.12.19 S18W05 plage 9747 2001.12.19 5 N12E58 0070 CAO 9748 2001.12.20 4 S11E36 0030 CSO 9749 2001.12.20 3 S08E72 0080 CSO Total number of sunspots: 81 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) 2001.12 223.1 (1) 134.9 (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]