Solar Terrestrial Activity Report [Image] Last update April 9, 2001 at 03:20 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 major storm on April 8, high latitude stations reported severe storming between 11 and 15h UT. Solar wind speed ranged between 463 and 728 km/sec. A solar wind shock was observed at 10:23 UT at SOHO with solar wind speed increasing abruptly from 470 to 710 km/sec. This shock is associated with the halo CME observed after an X5 flare on April 6. Solar flare activity was very low. Solar flux was 169.2, the planetary A index was 41 (3-hour K indices: 3146 6455, Boulder K indices: 3245 5455). Regions 9406 and 9407 were quiet and stable, both regions are rotating off the visible disk. Region 9415 developed several new spots but was otherwise mostly unchanged and quiet. The region is still capable of producing occasional major flares. Region 9417 was unchanged and quiet, a minor M class flare is possible. Region 9418 developed slowly and was quiet. Minor M class flares are possible. Region 9420 was quiet and stable, as were regions 9421 and 9422. New region 9423 emerged in the northeast quadrant near the central meridian. New region 9424 emerged in the southeast quadrant. Flares and CMEs No flaring of significance was observed on April 8. 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 9 with a chance of isolated minor storm intervals, quiet to unsettled is expected on April 10-11. 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 9406 2001.03.28 2 N27W73 0120 HAX 9407 2001.03.28 1 N11W81 0070 HSX 9410 2001.03.30 S36W73 plage 9411 2001.03.30 N08W70 plage 9412 2001.03.30 S16W39 plage 9414 2001.04.02 S23W19 plage 9415 2001.04.03 34 S21E05 0790 EKO beta-gamma-delta 9416 2001.04.03 N17W85 plage 9417 2001.04.03 21 S09W12 0140 DAO 9418 2001.04.04 19 N27E19 0230 EAO 9419 2001.04.04 N08W64 plage 9420 2001.04.05 1 S06E36 0080 HSX 9421 2001.04.06 1 S16W57 0020 HSX 9422 2001.04.06 1 S12E64 0050 HSX 9423 2001.04.07 3 N21E03 0000 BXO 9424 2001.04.07 5 S16E34 0000 BXO Total number of sunspots: 88 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) 2001.04 207.7 (1) 56.0 (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]