Solar Terrestrial Activity Report [Image] Last update August 26, 2001 at 05:05 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update August 1, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update August 1, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update August 1, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update July 27, 2001)] Recent development The geomagnetic field was quiet to active on August 25. Solar wind speed ranged between 344 and 437 km/sec. A minor disturbance arrived at ACE at 14:10 UTC and intensified slowly until late evening when solar wind speed was decreasing slowly and the interplanetary magnetic field swung northwards. Solar flare activity was high. Solar flux was 187.6 (the measurement at 23h UTC was used as the 20h UTC observation was enhanced by the X flare earlier in the day), the planetary A index was 10 (3-hour K indices: 1112 3443, Boulder K indices: 1112 3433). Region 9580 was quiet and stable. Region 9585 decayed quickly and will likely continue decaying today. Region 9587 reemerged and developed quickly. The region could already produce minor M class flares. Region 9590 was quiet and stable. Region 9591 still has a very strong magnetic delta within the main penumbra as well as a weak delta in the leading spots section. Further M and X class flaring is likely and there is a possibility of a large proton event as well. Region 9594 decayed slowly and was spotless by the end of the day. New region 9596 rotated into view at the northeast limb.. Flares and CMEs A total of 107 C, 2 M and 1 X class events were observed on August 25. Region 9591 produced a C1.8 flare at 07:10, a C3.6 flare at 07:32, a C2.6 flare at 08:23, a C2.5 flare at 08:44, an M1.2 flare at 09:28, a C3.7 flare at 09:57, a C1.9 flare at 10:49, a C2.0 flare at 13:01, a C3.2 flare at 13:27, a C2.2 flare at 15:33, a major X5.3/3B long duration event peaking at 16:45 (with associated moderately strong type II and IV radio sweeps and a fast and large full halo CME. The CME will likely impact Earth on August 27 and cause active to severe storm conditions), an M1.1 flare at 19:56 and aC4.0 flare at 21:26 UTC. Region 9587 generated a C9.6 flare at 22:23 and a C7.0 flare at 23:45 UTC. The background x-ray flux is at the class C2 level. Coronal holes A well defined coronal hole in the southern hemisphere was in a geoeffective position on August 23-24. Forecast The geomagnetic field is expected to be quiet to minor storm on August 26 and unsettled to severe storm on August 27. The possible presence of a coronal stream at the time of the arrival of the CME (associated with the X flare on August 25) could prevent the geomagnetic storm from reaching severe storm levels. 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 9580 2001.08.14 1 N24W68 0090 HSX 9582 2001.08.15 N27W61 plage 9584 2001.08.16 S12W63 plage 9585 2001.08.16 17 N13W44 0110 EAI 9587 2001.08.17 7 S10W55 0060 DSO beta-gamma 9589 2001.08.20 N15W86 plage 9590 2001.08.20 3 S29E12 0180 HAX 9591 2001.08.21 32 S19E32 0740 FKI beta-gamma-delta 9593 2001.08.23 N00W25 plage 9594 2001.08.24 1 N37W10 0000 AXX 9595 2001.08.24 N16E14 plage 9596 2001.08.25 1 N23E79 0120 HAX Total number of sunspots: 62 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.03 208.2 138.5 119.9 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.7 2000.08 163.0 130.5 118.6 (-1.1) 2000.09 182.1 109.7 116.3 (-2.3) 2000.10 167.4 99.4 114.5 (-1.8) 2000.11 178.8 106.8 112.8 (-1.7) 2000.12 173.6 104.4 112.1 (-0.7) 2001.01 166.6 95.6 108.8 (-3.3) 2001.02 146.6 80.6 (104.1 predicted, -4.7) 2001.03 177.7 113.5 (101.4 predicted, -2.7) 2001.04 177.7 108.2 (100.2 predicted, -1.2) 2001.05 147.1 97.3 (99.5 predicted, -0.7) 2001.06 173.0 134.0 (96.8 predicted, -2.7) 2001.07 131.3 82.2 (94.9 predicted, -1.9) 2001.08 155.3 (1) 129.5 (2) (95.5 predicted, +0.6) 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]