Solar Terrestrial Activity Report [Image] Last update April 10, 2001 at 02:00 UT. [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, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April 2, 2001)] [Historical solar and geomagnetic data charts 1954-2000 (last update April 8, 2001)] Recent development The geomagnetic field was quiet to minor storm on April 9. Solar wind speed ranged between 501 and 726 km/sec. Solar flare activity was high. Solar flux was 164.8, the planetary A index was 19 (3-hour K indices: 2444 3532, Boulder K indices: 2443 3432). Regions 9406 and 9407 were quiet and stable, both regions have rotated. Region 9415 was mostly unchanged and could produce further major flares. Region 9417 decayed slowly and was quiet. Region 9418 decayed slightly and was quiet. Region 9420 was quiet and stable, as were regions 9421 and 9422. Region 9423 was quiet and stable, no spots are visible early on April 10. Region 9424 was quiet and stable. New region 9425 emerged south of region 9417. Flares and CMEs A total of 5 C and 1 M class events were observed on April 9. Region 9415 produced a long duration C6.4 event peaking at 02:56 UT, the event was associated with a strong type IV sweep and a diffuse halo coronal mass ejection (which was difficult to observe due to a CME with an origin to the southeast of region 9415, that CME was caused by a filament eruption beginning at 23:36 UT on April 8). Region 9415 generated a C3.0 flare at 06:57, a C6.1 flare at 09:28, a C2.1 flare at 18:29 and a major M7.9/2B flare peaking at 15:34 UT. A strong type II sweep and a weak type IV sweep was associated with this event, as was a CME. The CME is aimed nearly directly at Earth and will impact the magnetosphere sometime between 21h UT on April 10 and noon on April 11. This will likely result in minor to severe storming, very severe storming is possibly at high latitudes. The flare was a weak particle event, the above 10 MeV proton flux has not yet reached event level (10 pfu). The background x-ray flux is at the class B4 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 10 and active to very severe storm on April 11. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very 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 9406 2001.03.28 1 N27W86 0080 HSX 9407 2001.03.28 1 N11W94 0060 HSX 9410 2001.03.30 S36W86 plage 9411 2001.03.30 N08W83 plage 9412 2001.03.30 S16W52 plage 9414 2001.04.02 S23W32 plage 9415 2001.04.03 32 S22W07 0760 EKI beta-gamma-delta 9417 2001.04.03 10 S08W27 0120 DAO 9418 2001.04.04 17 N27E07 0210 EAO 9419 2001.04.04 N08W77 plage 9420 2001.04.05 1 S07E22 0040 HSX 9421 2001.04.06 1 S16W72 0030 HSX 9422 2001.04.06 2 S12E51 0070 HSX 9423 2001.04.07 4 N20W10 0010 BXO 9424 2001.04.08 2 S16E22 0020 CSO 9425 2001.04.09 4 S24W26 0020 BXO Total number of sunspots: 75 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.01 158.1 90.1 112.9 (+1.8) 2000.02 174.1 112.9 116.8 (+3.9) 2000.03 208.2 138.5 119.9 (+3.1) 2000.04 184.2 125.5 120.8 (+0.9) cycle 23 sunspot max. 2000.05 184.9 121.6 119.0 (-1.8) 2000.06 179.8 124.9 118.7 (-0.3) 2000.07 202.3 170.1 119.8 (+1.1) 2000.08 163.0 130.5 118.6 (-1.2) 2000.09 182.1 109.7 116.2 (-2.4) 2000.10 167.4 100.1 (114.6 predicted, -1.6) 2000.11 178.8 106.5 (112.6 predicted, -2.0) 2000.12 173.6 104.5 (110.1 predicted, -2.5) 2001.01 166.6 95.7 (106.3 predicted, -3.8) 2001.02 146.6 80.1 (101.9 predicted, -4.4) 2001.03 177.7 114.2 (98.4 predicted, -3.5) 2001.04 202.9 (1) 62.1 (2) (97.1 predicted, -1.3) 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. ------------------------------------------------------------------------ Do you know about the survey which will be held this Summer among the listeners of WWV and WWVH? There is information about this survey at 16 minutes past the hour on WWV and at 47 minutes past the hour on WWVH. If you want to participate send an email with your name and address. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]