Solar Terrestrial Activity Report [Image] Last update December 20, 2001 at 04:30 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 unsettled on December 19. Solar wind speed ranged between 352 and 451 km/sec. Solar flare activity was moderate. Solar flux was 208.2, the planetary A index was 9 (3-hour K indices: 3133 2222, Boulder K indices: 3223 2222). Region 9733 decayed slowly and was mostly quiet. Minor M class flares are possible while the region is rotating over the northwest limb today. Region 9738 decayed further and was mostly quiet. Region 9739 was mostly unchanged and could produce another minor M class flare while rotating over the southwest limb today. Region 9741 developed slowly and was quiet. Region 9742 decayed slowly and simplified. The region could produce occasional minor M class flares. Region 9743 was quiet and stable. Region 9745 appears to be decaying and could soon become spotless. New region 9746 emerged briefly in the southeast quadrant and is currently spotless. New region 9747 rotated into view at the northeast limb and appears to be decaying. Flares and CMEs A total of 10 C and 1 M class events were recorded on December 19. Region 9733 produced a C3.9/1F flare at 01:15 UTC. Region 9742 generated a C4.6 long duration event peaking at 05:17 UTC. Region 9739 was the source of a C1.6 flare at 13:57 and an M1.3 impulsive flare at 17:06 UTC. Region 9738 managed a C2.2 flare at 19:50 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 20-22. There is a chance of a minor coronal stream based disturbance on December 23. 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 15 N13W75 0310 EAI beta-gamma 9734 2001.12.09 S16W49 plage 9737 2001.12.10 S27W65 plage 9738 2001.12.12 8 S19W21 0040 DAO 9739 2001.12.13 7 S14W82 0270 EAO 9740 2001.12.13 S06W23 plage 9741 2001.12.13 4 N07W09 0020 CAO 9742 2001.12.15 24 N12E27 0320 EAI beta-gamma 9743 2001.12.16 2 S10E34 0120 HAX 9744 2001.12.16 S05W16 plage 9745 2001.12.18 4 N18E48 0030 BXO 9746 2001.12.19 2 S18E08 0020 BXO now spotless 9747 2001.12.19 2 N12E71 0030 BXO Total number of sunspots: 68 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) 2001.12 223.2 (1) 129.4 (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]