Solar Terrestrial Activity Report [Image] Last update July 28, 2000 at 07:20 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 moderate on July 27. Solar wind speed was in the range 335-399 km/sec. A fairly strong solar wind shock was observed at 05:40 on July 28 as the CME observed on July 25 reached ACE. Solar wind speed increased abruptly from 340 to 450 km/sec and the interplanetary magnetic field was initially very strongly southwards. This could cause minor to severe geomagnetic storming. The geomagnetic field was quiet to active. The planetary A index was 9 (Kp: 4212 1223). Solar flux was 162.4. Region 9090 decayed slowly. Further minor M class flares are possible as the region rotates over the west limb today and tomorrow. Region 9091 decayed into spotless plage. Regions 9094 and 9096 were quiet and stable. Region 9097 decayed slowly and simplified. Occasional minor M class flares are still possible. Regions 9099, 9100, 9101, 9102, 9103 and 9104 were all quiet and stable. New region 9105 rotated partly into view at the northeast limb. New region 9106 emerged in the southwest quadrant. Flares and CMEs A total of 10 C and 3 M class events were observed on July 27. Region 9090 produced an M2.4 impulsive flare at 04:10, a C3.9 flare at 05:56, a C4.1 flare at 09:17, a C2.7 flare at 12:44, a C3.7 flare at 14:40 and an impulsive M1.2 flare at 23:42 UTC. Region 9097 generated a C2.3 flare at 07:13 UTC. Region 9087 behind the southwest limb was the source of a long duration M1.5 event peaking at 17:11. This event was also the likely source of an enhancement in the above 10 MeV proton flux early on July 28. The background x-ray flux is at the class B7 level. Coronal holes 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 unsettled to major storm on July 28 and quiet to active on July 29. 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 no. Location at region numbered sunspots midnight Area Classification Comment 9090 20000716 9 N14W76 0320 FAI beta-gamma 9091 20000716 S04W77 plage 9094 20000717 1 S22W67 0020 HRX 9096 20000718 1 S10W46 0010 HSX 9097 20000718 23 N09W41 0250 DAI beta-gamma 9099 20000719 1 N15W28 0060 HSX 9100 20000722 8 S31W02 0130 CSO 9101 20000722 1 S13W05 0020 HSX 9102 20000725 1 S19E30 0000 AXX 9103 20000726 3 N09E16 0020 CRO 9104 20000726 1 S23E65 0080 HSX 9105 20000727 1 N13E81 0050 HSX 9106 20000727 4 S10W15 0010 CSO Total number of sunspots: 54 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 2000.07 209.8 (1) 216.8 (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]