Solar Terrestrial Activity Report [Image] Last update July 25, 2000 at 07:00 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 low on July 24. Solar wind speed was in the range 331-402 km/sec. The geomagnetic field was quiet to unsettled. The planetary A index was 8 (Kp: 2322 2322). Solar flux was 225. Region 9087 decayed slowly. Minor M flares are still likely and there is a small chance of a major flare before the region rotates behind the west limb on July 26. Region 9090 was mostly unchanged and remains capable of generating an isolated major flare. Regions 9091, 9094 and 9096 were quiet and stable. Region 9095 did not change significantly and could produce a minor M class flare before rotating over the west limb late today. Region 9097 could produce further major flares and is currently located in a position near and above the central meridian. Regions 9099 and 9101 were quiet and stable. Region 9100 developed slowly and could produce a minor M class flare. Flares and CMEs A total of 7 C class events were observed on July 24. Region 9097 produced a C3.6/1F flare at 01:51 UTC. Region 9090 generated a C2.2 flare at 08:19 and a C3.8 flare at 20:02 UTC. Region 9100 was the source of a C2.8 flare at 16:00 UTC while region 9087 managed a C5.2 flare at 22:34 UTC. Region 9097 produced a major M8.0/2B impulsive flare at 02:49 UTC (a weak type II sweep was associated with this event and LASCO images have so far not revealed any large CME) and an M3.7/2N flare at 04:56 UTC. These events occurred with region 9097 positioned right over the central meridian. If there was any CME associated with the flares the CME will impact Earth, most probably on July 27. 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. July 22: A nearly full halo CME was observed in LASCO images following the M3.7 long duration proton producing event in region 9085 near noon. A terrestrial impact is likely on July 25. The background x-ray flux is at the class C1-C2 level. Coronal holes A large coronal hole in the northern hemisphere could rotate into a partly geoeffective position on July 24-26. A well defined, isolated coronal hole in the southern hemisphere will rotate into a geoeffective position on July 25 and cause a geomagnetic disturbance on July 28. Forecast The geomagnetic field is expected to be to quiet to active on July 25, possibly with minor storm intervals. Quiet to active is likely on July 26 while unsettled to minor storm is possible on July 27-28 due to coronal streams. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor to 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 no. Location at region numbered sunspots midnight Area Classification Comment 9087 20000714 26 S11W67 0560 FAC beta-gamma 9089 20000715 N13W75 plage 9090 20000716 30 N13W36 0360 FAI beta-gamma 9091 20000716 2 S06W37 0020 HSX 9093 20000717 S12W88 plage 9094 20000717 1 S23W28 0010 HSX 9095 20000717 6 N24W77 0100 ESO 9096 20000718 8 S12W06 0040 DSO 9097 20000718 28 N06W01 0540 EKC beta-gamma 9098 20000719 S02W87 plage 9099 20000719 1 N13E12 0070 HSX 9100 20000722 11 S32E40 0100 EAO 9101 20000722 2 S17E42 0020 HSX Total number of sunspots: 115 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 2000.07 213.5 (1) 196.8 (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]