Solar Terrestrial Activity Report [Image] Last update July 26, 2000 at 07:05 UTC. /Because of my vacation the text on this page will be updated occasionally until July 31. No charts will be produced until normal daily updates start on August 4/ [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update July 1, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update July 1, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update July 1, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update April 12, 2000)] Recent development Solar flare activity was high on July 25. Solar wind speed was in the range 336-395 km/sec. A minor solar wind shock was observed at ACE at 13:26 UTC with an abrupt increase in solar wind speed of 40 km/sec. The interplanetary magnetic field remained mostly northwards all day. Another minor solar wind shock was observed at 02:58 UTC on July 26, this time there was an abrupt speed increase from 345 to 380 km/sec. The IMF remained northwards until just before 05h UTC when a moderate southward swing occurred. The geomagnetic field was quiet to unsettled. The planetary A index was 7 (Kp: 2212 2323). Solar flux was 201.8. Region 9087 decayed slowly. Further minor M flares are possible when the region rotates over the west limb today. Region 9090 developed slowly and could produce minor M flares and possibly even a major flare. Regions 9091, 9094 and 9096 were quiet and stable. Region 9095 was quiet and rotated off the visible disk early on July 26. Region 9097 was mostly unchanged and could produce further major flares. Regions 9099 and 9101 were quiet and stable. Region 9100 developed slowly and could produce a minor M class flare. New region 9102 rotated into view at the southeast limb. Flares and CMEs A total of 7 C and 3 M class events were observed on July 25. Region 9097 produced a major M8.0/2B impulsive flare at 02:49 UTC. A weak type II sweep was associated with this event. As the event occurred at the center of the visible solar disk the associated fairly small, full halo CME will impact Earth, most likely sometimes between late on July 27 and noon on July 28. Region 9097 was also the source of a C2.5 flare at 10:21, a C2.4 flare at 14:51, a C4.5 flare at 16:26 and an M1.2/1B flare at 18:46 UTC. Region 9087 generated an M3.7/2N flare at 04:56 UTC. Region 9090 produced a C6.2 flare at 12:41 and a C4.4 flare at 21:49 UTC. July 23: A large filament eruption was observed in the morning to the west of region 9097. A partial halo CME was observed later in LASCO images and there is a fair chance of a terrestrial impact on July 26. The background x-ray flux is at the class C1 level. Coronal holes A large coronal hole in the northern hemisphere may have been in a partly geoeffective position on July 24-26. A well defined, isolated coronal hole in the southern hemisphere was in a geoeffective position on July 25 and could cause a geomagnetic disturbance on July 28. Forecast The geomagnetic field is expected to be to quiet to active on July 26 while unsettled to minor storm is possible on July 27-28 due to coronal streams. Geomagnetic activity could increase to major storm levels on July 28 when the halo CME observed on July 25 arrives. 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 no. Location at region numbered sunspots midnight Area Classification Comment 9087 20000714 12 S12W80 0380 FAC beta-gamma 9089 20000715 N13W88 plage 9090 20000716 44 N15W48 0450 FAI beta-gamma 9091 20000716 1 S06W51 0000 AXX 9094 20000717 5 S22W41 0040 CSO 9095 20000717 2 N25W89 0050 CSO 9096 20000718 7 S12W20 0040 CSO 9097 20000718 26 N08W15 0510 EKC beta-gamma 9099 20000719 1 N14W02 0060 HSX 9100 20000722 11 S33E26 0130 ESO 9101 20000722 12 S15E24 0040 CSO 9102 20000725 1 S21E60 0010 HRX Total number of sunspots: 122 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.06 169.8 137.7 93.1 (+2.6) 1999.07 165.6 113.5 94.3 (+1.2) 1999.08 170.7 93.7 97.5 (+3.2) 1999.09 135.7 71.5 102.3 (+4.8) 1999.10 164.8 116.7 107.8 (+5.5) 1999.11 191.5 133.2 110.9 (+3.1) 1999.12 169.8 84.6 111.0 (+0.1) 2000.01 158.1 90.1 (114.0 predicted, +3.0) 2000.02 174.1 112.9 (116.8 predicted, +2.8) 2000.03 208.2 138.5 (119.5 predicted, +2.7) 2000.04 184.2 125.3 (121.6 predicted, +2.1) 2000.05 184.9 120.8 (122.4 predicted, +0.8) 2000.06 179.8 124.9 2000.07 213.1 (1) 204.3 (2) 1) Running average based on the daily 20:00 UTC solar flux value at 2800 MHz. 2) Unofficial, accumulated value. The official value 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 in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]