Solar Terrestrial Activity Report [Image] Last update April 7, 2001 at 05:50 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 January 18, 2001)] Recent development The geomagnetic field was quiet to unsettled on April 6. Solar wind speed ranged between 449 and 552 km/sec. Solar flare activity was high. Solar flux was 191.7, the planetary A index was 12 (3-hour K indices: 1133 3333, Boulder K indices: 2132 3333). Regions 9406 and 9407 were quiet and stable. Region 9408 was quiet and rotated off the visible disk early today. Region 9412 was quiet and stable. Region 9413 was quiet and stable. Region 9415 developed slowly and has a strong magnetic delta configuration. Further major flares are likely. Region 9417 developed slowly and could produce a minor M class flare. Region 9418 was mostly unchanged and could produce minor M class flares. Region 9420 was quiet and stable. Flares and CMEs A total of 3 C and 1 X class events were recorded on April 6. Region 9417 generated a C7 flare at 18:15 UT. Region 9415 produced a C7.7 flare at 01:54, a C5 flare at 17:32 and an impressive major X5.6 flare at 19:21 UT. A large and fast full halo coronal mass ejection was observed in LASCO C2 and C3 images after the eruption. The CME is geoeffective and could trigger a major geomagnetic storm on April 8. April 5: Region 9415 was the origin of a major long duration M5.1/2N event peaking at 17:25 UT. A weak type IV sweep was recorded. A large and wide full halo coronal mass ejection was observed in LASCO C3 images starting at 17:42 UT. The CME will impact Earth, most likely on April 7. The background x-ray flux is at the class C1 level. Coronal holes A trans equatorial coronal hole was in a geoeffective position on April 5 (due to CMEs the coronal stream is not likely to be noticed when it reaches Earth on April 8). Forecast The geomagnetic field is expected to be quiet to major storm on April 7 and active to severe storm on April 8. 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 9403 2001.03.26 S15W87 plage 9404 2001.03.27 S03W72 plage 9406 2001.03.28 4 N28W50 0160 CSO 9407 2001.03.28 3 N11W54 0050 CSO 9408 2001.03.28 2 S09W88 0160 HAX 9410 2001.03.30 S36W47 plage 9411 2001.03.30 N08W44 plage 9412 2001.03.30 2 S16W13 0010 BXO 9413 2001.04.01 1 N10W86 0100 HAX 9414 2001.04.02 S23E07 plage 9415 2001.04.03 11 S21E33 0860 DKI beta-gamma-delta 9416 2001.04.03 N17W59 plage 9417 2001.04.03 13 S08E14 0180 DAO 9418 2001.04.04 8 N27E45 0200 DAO 9419 2001.04.04 N10W46 plage 9420 2001.04.05 2 S06E62 0070 HSX Total number of sunspots: 46 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) 2001.04 218.8 (1) 43.2 (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]