Solar Terrestrial Activity Report [Image] Last update September 18, 2002 at 03:45 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 active on September 17. Solar wind speed ranged between 391 and 518 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 194.0, the planetary A index was 13 (3-hour planetary K indices: 2333 4333, Boulder K indices: 2333 4323). Region 10105 changed its appearance a lot. The main penumbra lost nearly half of its area, while new penumbrae formed south and northwest of that penumbra. A magnetic delta could be forming inside one of the new southern penumbrae. Occasional M class flares are possible. Region 10107 decayed further losing about half of its penumbral area. Region 10110 decayed and only has a single small spot left, the region will rotate to the northwest limb today. Region 10114 decayed quickly and by the end of the day had only a few small spots left outside of the leading main penumbra. Region 10115 developed moderately quickly and could soon eclipse region 10105 as the largest region on the disk. New negative polarity flux emerged near the trailing positive polarity area. M class flares are possible. Region 10116 was nearly spotless, then began to develop quickly. The positive and negative polarity areas are currently mixed and the region may be capable of producing a minor M class flare. Region 10117 was quiet and stable. Region 10118 decayed and was spotless at the end of the day. Region 10119 developed further and early on Sept. 18 it appears as if a magnetic delta structure is forming. Region 10120 decayed slowly and was quiet. Region 10121 was quiet and stable. Region 10122 was quiet and stable. New region 10123 emerged in the southeast quadrant and is developing slowly. A new region emerged just north of the equator in the northwest quadrant but was not noticed by SEC/NOAA. Flares and CMEs A total of 12 C class events was recorded on September 17. Region 10110 produced a C5.2 flare at 02:05 UTC, a strong type II radio sweep was associated with this flare. Region 10119 generated a C1.2 flare at 04:15, a C8.8 flare at 09:21, a C4.3 flare at 10:50, a C2.8 flare at 17:41 and a C2.5 flare at 19:29 UTC. Region 10114 was the source of a C2.0 flare at 05:54 and a long duration C8.6/1F event peaking at 08:20 UTC. The latter event should perhaps have been classified as two long duration events as there was a first peak at the C7 level near 07:30 UTC. Anyway the LDE was associated with a full halo CME. Although most of the ejected material headed southwestwards, material was seen all around the disk, only weakly over the north pole. The CME will likely cause a geomagnetic disturbance on September 20 with unsettled to minor storm likely. The background x-ray flux is at the class C1 level. Coronal holes No obvious coronal holes are currently rotating into geoeffective positions. Forecast The geomagnetic field is expected to be quiet to active on September 18-19 and quiet to minor storm on September 20. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to 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 10104 2002.09.07 N09W75 plage beta-gamma 10105 2002.09.07 26 S08W56 0560 DKI area near 0450 at midnight 10106 2002.09.08 N27W68 plage 10107 2002.09.08 4 N11W52 0090 DAO area too large, was near 0050 at midnight 10108 2002.09.10 S24W45 plage 10109 2002.09.10 S08W75 plage 10110 2002.09.10 1 N17W75 0030 HRX area too large, actually near 0010 10111 2002.09.12 N11W64 plage 10112 2002.09.12 N00W61 plage 10114 2002.09.14 14 S11W43 0130 DAO too many spots, area near 0090 at midnight beta-gamma 10115 2002.09.14 20 S03E02 0210 EAI area near 0350 at midnight beta-gamma 10116 2002.09.15 8 N15W20 0030 DSO area near 0070 at midnight 10117 2002.09.15 2 S10E46 0150 HKX 10118 2002.09.16 4 N13W01 0010 BXO now spotless 10119 2002.09.16 10 S14E32 0040 CAO beta-gamma-delta? 10120 2002.09.16 4 S19E43 0040 CSO 10121 2002.09.16 1 S14E53 0060 HSX 10122 2002.09.16 1 S18E62 0060 HSX 10123 2002.09.17 3 S16E30 0020 HRX too few spots, classification CSO Total number of sunspots: 98 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) 2002.09 191.5 (1) 123.3 (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]