Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update August 23, 1999 at 04:10 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update August 2, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update August 2, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update August 2, 1999)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet to unsettled on August 22. Solar wind speed ranged between 371 and 510 km/sec. The interplanetary magnetic field was weakly southwards early in the day becoming moderately strongly southwards by the end of the day. Unsettled to active conditions would have been expected. Surprisingly, early on August 23, major storming was observed. Solar flare activity was low. Solar flux was 172.7, the planetary A index was 11 (3-hour K indices: 1132 3333, Boulder K indices: 0122 3333). Region 8668 was mostly quiet and stable but could produce isolated C flares and perhaps even a minor M class flare. Region 8673 was quiet and stable. The region has M class flaring potential. Region 8674 developed slowly and only managed to produce C flares. M flares and occasional X flares are likely from this region for at least the next 2-3 days. Flares and CMEs On August 22 a total of 10 C flares were recorded. Region 8674 was the origin of 5 C flares. The most interesting ones were a C9.8 impulsive flare at 15:51 UTC and a C5.3 flare at 14:12 UTC. The latter event was accompanied by a strong type II sweep and a weak type IV sweep. A minor coronal mass ejection was observed as well over the east limb. The background x-ray flux is at the class B9 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to major storm on August 23. Low frequency (below 2 MHz) radio wave 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 8665 990811 S26W79 plage 8667 990812 N24W59 plage 8668 990813 17 N23W36 0240 DHO 8669 990814 S21W65 plage 8672 990818 N16W62 plage 8673 990819 13 S20E43 0490 DKO 8674 990820 18 S25E48 0440 FAI Total number of sunspots: 48 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 9807 114.0 66.6 65.5 (+3.0) 9808 136.0 92.2 67.8 (+2.3) 9809 138.3 92.9 69.5 (+1.7) 9810 117.2 55.5 70.5 (+1.0) 9811 140.1 74.0 73.0 (+2.5) 9812 150.1 81.9 77.9 (+4.9) 9901 140.6 62.4 82.6 (+4.7) 9902 141.9 66.1 (85.6 predicted, +3.0) 9903 126.3 69.1 (87.6 predicted, +2.0) 9904 117.2 63.9 (91.2 predicted, +3.6) 9905 148.4 106.3 9906 169.8 137.4 9907 165.6 113.5 9908 154.7 (1) 84.9 (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]