Solar Terrestrial Activity Report [Image] Last update August 21, 2002 at 03:25 UTC. Minor update posted at 06:27 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 7, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update August 7, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update August 7, 2002)] [Historical solar and geomagnetic data charts 1954-2002 (last update August 16, 2002)] Recent development The geomagnetic field was quiet to minor storm on August 20. Solar wind speed ranged between 451 and 518 km/sec. A solar wind shock was observed at 15:58 UTC at ACE. Towards the end oft he day the interplanetary magnetic field swung gradually stronger southwards and was fully southwards at midnight. The source of this disturbance may have been a halo CME observed on August 18 after a flare in region 10069. Solar flare activity was high. Solar flux was 227.5, the planetary A index was 23 (3-hour planetary K indices: 4423 2455, Boulder K indices: 4422 2243). Region 10066 decayed and was spotless at the end of the day. Region 10067 decayed slowly and quietly. Region 10069 lost some of its penumbral coverage in the northern section of the main penumbra. A positive polarity spot, just southwest of the huge main negative polarity umbra, developed and approached the main spot. This created an interesting magnetic delta structure. Very strong magnetic shear will occur if the two spots continue to close in on each other. There is still a chance of a major X class proton flare. Region 10076 decayed and was spotless early on August 21. Region 10079 decayed further losing quite a few trailing and intermediate spots. Region 10080 developed some new spots northwest of the main penumbra. The main penumbra itself lost some of its area. Region 10083 was mostly quiet and stable, as was region 10084. Region 10085 was mostly unchanged and may be capable of producing another minor M class flare. Comment added at 06:27 UTC on August 21: Region 10069 produced a major X1.0 flare at 05:34 UTC. The flare was impulsive and early LASCO images do not reveal any significant CME. Flares and CMEs A total of 18 C and 5 M class events was recorded on August 20. Region 10069 produced a major M5.0/1N flare at 01:40, an M1.4 flare at 01:49, a C5.5 flare at 02:14, an M1.4 flare at 02:57, a C2.6 flare at 03:43, a C4.0 flare at 05:15, an M3.4/1B flare at 08:26, a C5.2 flare at 17:06, a C9.9 flare at 17:55, a C6.2 flare at 22:28 and a C5.4 flare at 22:45 UTC. Region 10079 generated a C2.7 flare at 06:20, a C2.6 flare at 09:47, a C2.0 flare at 10:06 and a C3.3 flare at 10:31 UTC. Region 10083 was the source of a C5.4 flare at 14:37 UTC, while region 10081 managed a C3.0 flare at 15:52 UTC. Region 10085 produced a C3.3 flare at 16:40 and an M1.2/1F flare at 21:14 UTC. August 19-20: Region 10069 produced several M class flares, some of them associated with weak halo CMEs. Minor solar wind shocks can be expected on August 21 and 22. The background x-ray flux is at the class C1-C2 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be unsettled to minor storm on August 21-22, possibly with isolated major storm intervals. Long distance medium wave (AM) band 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 Location region numbered no. at Area Classification Comment sunspots midnight 10066 2002.08.09 3 N15W73 0040 HSX now spotless 10067 2002.08.10 11 N10W62 0080 DAO 10068 2002.08.10 S10W66 plage 10069 2002.08.11 47 S08W44 1850 EKC beta-gamma-delta 10075 2002.08.12 S11W76 plage 10076 2002.08.12 1 N13W29 0010 HSX now spotless 10077 2002.08.13 S18W30 plage 10079 2002.08.14 31 S22W22 0230 EAI 10080 2002.08.14 13 N16W10 0120 CAO 10081 2002.08.16 N18E08 plage 10082 2002.08.17 N20W33 plage 10083 2002.08.17 5 S17E25 0030 DSO beta-gamma 10084 2002.08.18 5 S17E39 0100 CSO 10085 2002.08.19 3 S11E56 0480 CKO Total number of sunspots: 137 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 2001.07 131.3 81.8 111.7 (+1.9) 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 (114.0 predicted, -0.5) 2002.03 179.5 98.4 (110.3 predicted, -3.7) 2002.04 189.8 120.4 (104.5 predicted, -5.8) 2002.05 178.4 120.8 (100.0 predicted, -4.5) 2002.06 148.7 88.5 (95.5 predicted, -4.5) 2002.07 173.5 99.9 (90.6 predicted, -4.9) 2002.08 182.5 (1) 134.9 (2) (86.6 predicted, -4.0) 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]