Solar Terrestrial Activity Report [Image] Last update September 7, 2002 at 04:40 UTC. Last minor update posted at 16:48 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update September 3, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 3, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 3, 2002)] [Historical solar and geomagnetic data charts 1954-2002 (last update August 16, 2002)] Recent development The geomagnetic field was quiet to unsettled on September 6. Solar wind speed ranged between 365 and 433 km/sec Solar flare activity was low. Solar flux was 178.1, the planetary A index was 10 (3-hour planetary K indices: 2333 3232, Boulder K indices: 2333 2111). Region 10094 decayed slowly and quietly. Region 10095 decayed, particularly in the trailing spot section. The region was quiet. Region 10096 decayed a lot losing almost half of its penumbral area. The trailing spots are disappearing. Region 10097 decayed quickly and could become spotless by the end of tomorrow if the current rate of decay continues. Region 10099 decayed further and was quiet. Region 10100 was quiet and stable, however, the leading penumbra appears to be splitting. Region 10101 decayed and was spotless by late afternoon. Region 10103 was the only region on the visible disk to develop during the day. The region is currently magnetically simple. A new region emerged late in the day near the northeast limb. Old region 10069 should rotate into view at the southeast limb within a couple of days. Comment added at 08:58 UTC on September 7: Spots are rotating into view at the southeast limb, possibly the return of old region 10069. ACE solar wind parameters indicate that a solar wind shock could occur within the next few hours. Perhaps the CME observed on September 5 will arrive earlier than expected? Comment added at 16:48 UTC: A strong solar wind shock was observed at SOHO at 15:57 UTC. Solar wind speed jumped abruptly from 360 to 600 km/sec. Major geomagnetic storming is likely for the remainder of today and the first half of tomorrow. Flares and CMEs A total of 3 C class events was recorded on September 6. None of the flares were optically correlated and probably had their origin just behind the east limb. A C9.2 flare was recorded at 16:28 and followed by a C5.3 flare at 16:44 UTC. September 5: A filament eruption just east of region 10102 at 16:24 UTC triggered a long duration C5.2 event from region 10102 peaking at 17:10 UTC. A full halo CME was associated with this event. The CME expanded quickly eastwards and slowly over the west limbs. Although Earth will not receive a direct hit, parts of the CME are likely to reach Earth on September 8. The background x-ray flux is at the class B8 level. Coronal holes A possible coronal hole in the southern hemisphere will rotate into a geoeffective position on September 7-8. Forecast The geomagnetic field is expected to be quiet to unsettled on September 7 and quiet to minor storm on September 8 due to a likely CME impact. 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 Location region numbered no. at Area Classification Comment sunspots midnight 10094 2002.08.29 5 S19W41 0110 CAO area too large, 10095 2002.08.29 33 N08W31 0360 FKI was near 0250 at midnight. 10096 2002.08.30 22 S16W15 0160 EAI too many spots 10097 2002.08.31 7 N12W47 0050 DSO 10098 2002.08.31 S10W02 plage 10099 2002.09.01 5 S05W43 0030 CSO 10100 2002.09.01 9 S19E06 0130 DAO 10101 2002.09.01 8 N02E05 0010 BXO only 1 spot observed, region is now spotless 10102 2002.09.02 N08E13 plage 10103 2002.09.03 20 N15E31 0140 DAO Total number of sunspots: 109 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.8 2001.08 162.9 106.4 113.6 (+1.8) 2001.09 233.2 150.7 114.1 (+0.5) 2001.10 207.6 125.5 114.0 (-0.1) 2001.11 210.6 106.5 115.5 (+1.5) 2001.12 235.1 132.2 114.6 (-0.9) 2002.01 226.6 114.1 113.5 (-1.1) 2002.02 205.0 107.4 114.7 (+1.2) 2002.03 179.5 98.4 (113.2 predicted, -1.5) 2002.04 189.8 120.4 (108.7 predicted, -4.5) 2002.05 178.4 120.8 (104.2 predicted, -4.5) 2002.06 148.7 88.5 (99.7 predicted, -4.5) 2002.07 173.5 99.9 (94.9 predicted, -4.8) 2002.08 183.6 116.4 (90.8 predicted, -4.1) 2002.09 175.1 (1) 43.6 (2) (87.1 predicted, -3.7) 1) Running average based on the daily 20:00 UT solar flux value at 2800 MHz. 2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number is typically 25-45% 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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News]