Solar Terrestrial Activity Report [Image] Last update April 13, 2001 at 02:50 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 severe storm on April 12. Solar wind speed ranged between 554 and 852 km/sec. Solar flare activity was high. Solar flux was 149.0, the planetary A index was 38 (3-hour K indices: 7655 3311, Boulder K indices: 7553 3321). Region 9415 was mostly unchanged and has a magnetic delta inside the leading penumbra. Further major flaring is possible. Region 9417 decayed slowly and was quiet. Region 9418 decayed slowly and was quiet. Region 9420 decayed slowly while region 9422 was mostly unchanged and quiet. Region 9423 was quiet and is spotless early on April 13. Region 9424 developed slowly and was quiet. Regions 9426 and 9427 developed slowly and were quiet. Comment added at 16:07 UT on April 12: Region 9415 was the source of a long duration X2.2 event peaking at 10:28 UT. A moderate type II sweep was recorded and a halo CME was observed. The CME will likely reach Earth sometime between 15 UT on April 13 and 03 UT on April 14 and cause active to major storm conditions, possibly with isolated severe storming. Flares and CMEs A total of 1 M and 1 X class events were observed on April 12. Region 9415 produced an M1.3/1N flare at 03:04 UT and an X2.0 long duration event peaking at 10:28 UT. The X flare was accompanied by a moderate type II sweep, a weak type IV sweep, as well as an increase in proton fluxes. A full halo CME was observed in LASCO images. The CME will likely reach Earth sometime between 00 and 18h UT on April 14 and cause active to major storm conditions, possibly with isolated severe storming. April 11: Region 9415 generated an M2.3/1F flare at 13:26. This event was accompanied by a moderate type IV sweep and a weak type II sweep. A full halo CME was observed in LASCO C3 images starting at 14:42 UT. The CME will likely reach Earth sometime between noon on April 13 and the early hours of April 14 and cause active to major storm conditions. The background x-ray flux is at the class B3 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled until the arrival of the halo CME observed on April 11. A disturbance will then begin and cause active to major storm conditions. The geomagnetic field will likely be disturbed at this level for most of April 14 and 15. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor to useless. 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 9414 2001.04.02 S23W71 plage 9415 2001.04.03 22 S22W46 0520 DKI beta-gamma-delta 9417 2001.04.03 8 S06W66 0120 DAO 9418 2001.04.04 4 N27W33 0110 ESO 9420 2001.04.05 1 S07W18 0040 HSX 9422 2001.04.06 6 S12E09 0070 DAO 9423 2001.04.07 3 N20W52 0010 BXO now spotless 9424 2001.04.08 12 S17W20 0060 DSO 9425 2001.04.09 S24W64 plage 9426 2001.04.11 8 S09E25 0060 DSO 9427 2001.04.11 5 S08W26 0040 DSO Total number of sunspots: 69 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 (115.4 predicted, -0.8) 2000.11 178.8 106.5 (114.2 predicted, -1.2) 2000.12 173.6 104.5 (111.7 predicted, -2.5) 2001.01 166.6 95.7 (108.0 predicted, -3.7) 2001.02 146.6 80.1 (103.5 predicted, -4.5) 2001.03 177.7 114.2 (100.0 predicted, -3.5) 2001.04 192.0 (1) 79.1 (2) (98.8 predicted, -1.2) 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]