Solar Terrestrial Activity Report [Image] Last update April 13, 2002 at 04:40 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 active on April 12. Solar wind speed ranged between 383 and 490 km/sec. Solar flare activity was moderate. Solar flux was 211.9, the planetary A index was 13 (3-hour K indices: 4222 3333, Boulder K indices: 5222 3333). Region 9893 developed slowly with the major part of the development occurring in the trailing spots section. That part of the region is magnetically complex and major flares are possible. Region 9896 was quiet and stable. Region 9899 was quiet and stable, a minor M class flare may be possible. Region 9900 decayed and simplified. Flares above the C class level are unlikely. Region 9901 was unchanged and is capable of M class flare production. Region 9902 developed slowly and quietly. Region 9903 decayed and was spotless by the end of the day. Region 9904 decayed slowly and had only a single small spot left by the end of the day, the region could become spotless today. Region 9905 developed slowly and was quiet. Region 9906 developed explosively and is early on April 13 the largest region on the visible disk. The region has a strong magnetic delta structure and could be capable of generating X class flares. Region 9907 developed slowly and has a magnetic delta structure within the leading part of the region. A major flare is possible. New region 9908 emerged late on April 11 in the northwest quadrant and is an unimpressive region. Flares and CMEs A total of 7 C and 2 M class events were recorded on April 12. Region 9906 produced a C1.8 flare at 01:46 and a C3.0 flare at 08:42 UTC. Region 9907 generated a C5.0 flare at 03:09 and a C7.7 flare at 16:03 UTC. Region 9899 was the source of a C3.4 flare at 05:12 UTC. This flare was associated with weak type II and IV radio sweeps. Region 9893 produced an M1.4 flare at 13:10 UTC, while region 9901 generated an M4.0/1F flare at 18:02 with an associated weak type IV radio sweep. April 10: Region 9893 produced an impulsive major M8.2 flare at 12:31 UTC. The center of the M flare was located where the trailing magnetic delta structure was (at the time nearly over the central meridian). A fairly small and slow halo CME was observed in LASCO images from 13:27 UTC. This CME was best defined over the northeast quadrant and was faint elsewhere. The CME appeared to be a full halo CME in both the differencing movies and in LASCO C3 images. 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 active on April 13-14, possibly with minor storm intervals after the expected arrival of the CME observed following the major flare in region 9893 on April 10. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 9892 2002.04.02 N05W71 plage 9893 2002.04.03 31 N20W39 0390 EAI beta-gamma-delta 9895 2002.04.05 N06W33 plage 9896 2002.04.05 5 S11W19 0080 DSO 9897 2002.04.06 S02W87 plage 9898 2002.04.06 S18W15 plage 9899 2002.04.06 9 N17W04 0180 DSO 9900 2002.04.07 14 S28W57 0140 DAO area too large 9901 2002.04.07 17 N21W26 0190 DAI beta-gamma-delta 9902 2002.04.07 8 N14E19 0120 CSO 9903 2002.04.08 4 N18E19 0030 CRO now spotless 9904 2002.04.09 5 S15W49 0030 CRO 9905 2002.04.10 12 S15W25 0050 DAO beta-gamma-delta 9906 2002.04.11 20 S16E26 0190 DAI area too small, too few spots 9907 2002.04.11 14 S05E61 0380 EAI beta-gamma-delta 9908 2002.04.12 4 N05W25 0020 CAO Total number of sunspots: 143 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) 2002.04 207.1 (1) 87.5 (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]