Solar Terrestrial Activity Report [Image] Last update July 24, 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 23. Solar wind speed was in the range 381-440 km/sec. A disturbance (probably related to flare activity in regions 9087 and 9090 on July 20) arrived during the latter half of the day. No distinct solar wind shock was observed. The geomagnetic field was quiet to minor storm. The planetary A index was 20 (Kp: 2345 3433). Solar flux was 217.3. Region 9081 was quiet and stable and is rotating off the visible disk. Region 9085 decayed further and will rotate over the west limb early on July 25. Region 9087 decayed slowly. The magnetic delta configuration disappeared and major flares are becoming less likely. Region 9088 was quiet and stable and has rotated off the visible disk. 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 developed slowly and could produce a minor M class flare before rotating over the west limb late on July 25. Region 9097 did not change significantly and remains capable of isolated major flaring. Regions 9099, 9100 and 9101 were quiet and stable. Flares and CMEs A total of 5 C and 2 M class events were observed on July 23. Region 9087 produced a C2.8 flare at 01:25, a C2.8 flare at 05:37, a C4.5 flare at 09:26, an M1.5/1N flare at 10:00, an M1.1/1N flare at 14:13 and a C6.0/2N flare at 18:01 UTC. Region 9085 generated a C1.9 flare at 23:15 UTC. July 22: A couple of well placed filaments erupted early in the day and may have been associated with geoeffective CMEs. July 21: Region 9090 generated an impulsive major M5.5/2B flare at 14:37. A weak type II sweep was detected and a weak CME may have been produced. If so the CME could cause unsettled to minor storm conditions at Earth on July 24. 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 24-25, possibly with minor storm intervals. Quiet to unsettled 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 9081 20000711 1 N06W86 0030 HSX 9085 20000712 5 N16W75 0070 CAO 9087 20000714 42 S12W53 0650 FKC beta-gamma 9088 20000714 2 N23W92 0020 BXO 9089 20000715 N13W62 plage 9090 20000716 43 N13W21 0310 FAI beta-gamma 9091 20000716 2 S06W24 0030 HSX 9092 20000717 S25W88 plage 9093 20000717 S12W75 plage 9094 20000717 3 S23W14 0020 CSO 9095 20000717 9 N25W65 0070 ESO 9096 20000718 9 S13E08 0040 DSO 9097 20000718 26 N09E13 0630 EKC beta-gamma 9098 20000719 S02W74 plage 9099 20000719 1 N13E25 0070 HSX 9100 20000722 1 S31E47 0070 HSX 9101 20000722 2 S16E53 0020 CRO Total number of sunspots: 146 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 2000.07 213.0 (1) 189.8 (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]