Solar Terrestrial Activity Report [Image] Last update April 16, 2002 at 03:10 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update April 2, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April, 2002)] [Historical solar and geomagnetic data charts 1954-2002 (last update April 13, 2002)] Recent development The geomagnetic field was quiet to unsettled on April 15. Solar wind speed ranged between 317 and 388 km/sec. Solar flare activity was moderate. Solar flux was 203.3, the planetary A index was 7 (3-hour K indices: 2112 2333, Boulder K indices: 2111 2223). Region 9893 decayed slowly and rotated partly over the northwest limb. Region 9896 was quiet and stable, as was region 9899. Region 9901 decayed slowly. There is no obvious separation from region 9893. Regions 9902 and 9903 were quiet and stable. Region 9905 decayed slowly and was mostly quiet. Region 9906 decayed after the M class event early in the day. Further M class flares are possible but the region is significantly less complex than just a day ago. Region 9907 decayed slowly but could still produce minor M class flares. Region 9908 decayed and was spotless by noon. Region 9909 was quiet and stable. New region 9910 emerged in the southeast quadrant. A region just behind the southeast limb was quite active during the day and could rotate into view over the next couple of days. Flares and CMEs A total of 5 C and 2 M class events were recorded on April 15. Region 9893 produced a C9.8 flare at 02:51 and a long duration M1.2 event peaking at 23:24 UTC. Region 9906 was the source of a long duration M1.2 which peaked at 03:55 UTC. This event was associated with a nice full halo CME. LASCO C2 images show the first glimpse of this CME at 03:50 UTC. The CME will impact the Earth, probably sometime between noon on April 17 and 06h UTC on April 18, and could cause active to major geomagnetic storm conditions. Region 9901 generated a C3.0 flare at 11:42 UTC, while region 9905 managed a C3.1 flare at 17:36 UTC. 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 April 16 and most of April 17. The halo CME mentioned above will likely cause active to major storm conditions when it reaches the Earth sometime during the latter half of April 17 or early on April 18. 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 Location region numbered no. at Area Classification Comment sunspots midnight 9893 2002.04.03 10 N19W81 0350 EAI beta-gamma-delta 9895 2002.04.05 N06W72 plage 9896 2002.04.05 1 S09W60 0090 HSX 9898 2002.04.06 S18W54 plage 9899 2002.04.06 2 N19W44 0170 CSO area way too large, 9901 2002.04.07 11 N21W70 0350 DAO no obvious separation from region 9893 9902 2002.04.07 8 N12W28 0120 CSO 9903 2002.04.08 4 N16W13 0010 BXO 9904 2002.04.09 S14W82 plage 9905 2002.04.10 8 S14W69 0110 DSO area much too large 9906 2002.04.11 34 S15W14 0690 EKI beta-gamma 9907 2002.04.11 35 S04E21 0270 EAI 9908 2002.04.12 4 N05W70 0030 CRO now spotless 9909 2002.04.14 1 N11E56 0180 HSX 9910 2002.04.15 5 S21E50 0030 BXO Total number of sunspots: 123 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 2001.02 146.6 80.6 104.0 (-4.7) 2001.03 177.7 113.5 104.8 (+0.8) 2001.04 177.7 107.7 107.5 (+2.7) 2001.05 147.1 96.6 108.6 (+1.1) 2001.06 173.0 134.0 109.8 (+1.2) 2001.07 131.3 82.2 111.7 (+1.9) 2001.08 162.9 106.8 113.6 (+1.8) 2001.09 233.2 150.7 114.1 (+0.5) 2001.10 207.6 125.5 (113.3 predicted, -0.8) 2001.11 210.6 106.5 (112.7 predicted, -0.6) 2001.12 235.1 132.2 (109.3 predicted, -3.4) 2002.01 226.6 113.9 (106.0 predicted, -3.3) 2002.02 205.0 108.0 (104.6 predicted, -1.4) 2002.03 179.5 98.1 (100.4 predicted, -4.2) 2002.04 208.3 (1) 102.0 (2) (94.5 predicted, -5.9) 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 25-45% 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]