Solar Terrestrial Activity Report [Image] Last update July 27, 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 moderate on July 26. Solar wind speed was in the range 337-418 km/sec. A minor solar wind shock was observed at 02:58 UTC, solar wind speed increased abruptly from 345 to 380 km/sec. The IMF remained northwards until just before 05h UTC when a moderate southward swing occurred. Another minor solar wind shock was observed at 17:57 UTC when a sudden speed increase from 360 to 400 km/sec was noted. The interplanetary magnetic field was moderately southwards for most of the remainder of the day. The geomagnetic field was unsettled to active. The planetary A index was 20 (Kp: 3344 4344). Solar flux was 174.6. Region 9087 decayed slowly and rotated off the visible disk. Region 9090 decayed slowly. Minor M class flares are possible. Regions 9091, 9094 and 9096 were quiet and stable, region 9091 is spotless early on July 27. Region 9097 decayed slowly and could produce minor M class flares. There is a slight possibility for a major flare. Regions 9099, 9100, 9101 and 9102 were quiet and stable. New region 9103 emerged in the northeast quadrant. New region 9104 rotated into view at the southeast limb.. Flares and CMEs A total of 12 C and 1 M class events were observed on July 26. Region 9087 produced a C5.0 flare at 03:17 and a C2.6 flare at 08:14 UTC. Region 9090 was the source of a C8.9 flare at 04:07, a C4.6 flare at 05:12 and a C4.4 flare at 16:17 UTC. Region 9097 generated a C5.4 flare at 17:59 UTC. An M1.3 flare at 07:43 was not optically correlated to any of the visible regions. Region 9090 produced an M2.4 flare at 04:12 on July 27. 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 sometime between late on July 27 and noon on July 28. 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 quiet to minor storm on July 27-28 due to coronal streams. Geomagnetic activity could increase to major storm levels late on July 27 or 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 10 S11W94 0240 FAC beta-gamma 9090 20000716 27 N14W61 0380 FAI beta-gamma 9091 20000716 1 S04W64 0000 AXX 9094 20000717 1 S23W54 0020 HSX 9096 20000718 4 S11W33 0020 CSO 9097 20000718 28 N07W27 0390 DAC beta-gamma 9099 20000719 1 N14W14 0070 HSX 9100 20000722 9 S32E13 0130 ESO 9101 20000722 8 S14E10 0030 CSO 9102 20000725 3 S21E46 0010 BXO 9103 20000726 1 N08E28 0010 HRX 9104 20000726 1 S19E75 0090 HSX Total number of sunspots: 94 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 2000.07 211.6 (1) 211.2 (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]