Solar Terrestrial Activity Report [Image] Last update March 18, 2002 at 04:40 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update March 4, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update March 4, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update March 4, 2002)] [Historical solar and geomagnetic data charts 1954-2001 (last update January 12, 2002)] Recent development The geomagnetic field was quiet on March 17. Solar wind speed ranged between 285 and 316 km/sec. Solar flare activity was moderate. Solar flux was 184.4, the planetary A index was 4 (3-hour K indices: 1001 2221, Boulder K indices: 0000 1111). Region 9864 decayed slowly and quietly and has only one spot left (SEC/NOAA claims 3 spots and an undiminished area). Region 9866 decayed further and the trailing spots section lost about half of its penumbral coverage. The region has simplified but could still produce occasional minor M class flares. Region 9870 was quiet and stable. Region 9871 developed slowly and has several small areas of positive magnetic polarity surrounding the leading negative polarity penumbra. Further M class flares are possible. Region 9872 decayed slowly and quietly. Region 9873 was finally numbered. The region has developed slowly after the initial 24 hours following its emergence early on March 16. Flares and CMEs A total of 9 C and 2 M class events were recorded on March 17. Region 9871 produced a C3.1 flare at 04:58, a C4.5 flare at 17:05 and an impulsive M4.0 flare at 19:31 UTC. Region 9866 generated a C1.3 flare at 14:39 and a C1.8 flare at 15:39 UTC. An M1.3 flare at 10:19 UTC was optically uncorrelated. A long duration M1.0 event peaked at 02:31 UTC on March 18. A halo CME was shortly afterwards observed off the west limb and has become a full halo CME as I write this. The source of this CME is probably region 9866 but I haven't been able to verify that yet. The CME will likely reach the Earth sometime on March 20. March 15: Region 9866 was the source of a long duration M2.2 event which peaked at 23:10 UTC. This event occurred while the region was near the center of the solar disk and was accompanied by a fairly fast full halo CME. The brightest part of the CME was observed off the west limb, however, this CME will impact the Earth and could cause the most significant geomagnetic disturbance in several months. Minor to major storming is likely and there is a possibility of severe storming during the first 12-24 hours after the impact. The initial estimate of the time of arrival of this solar storm was somewhat optimistic. It now appears likely that the storm will reach the Earth before noon on March 18. The background x-ray flux is at the class B6 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 March 18 and unsettled to minor storm on March 19-20. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair but will likely become very poor later on today. 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 area too large, 9864 2002.03.07 3 N19W62 0050 CSO region has one HSX spot 9865 2002.03.08 N13W50 plage 9866 2002.03.08 24 S09W33 0470 EAI beta-gamma 9867 2002.03.11 S31W61 plage 9868 2002.03.11 N20W45 plage 9869 2002.03.11 N23W39 plage 9870 2002.03.11 1 S20W20 0120 HSX 9871 2002.03.13 15 S18E20 0330 ESO beta-gamma 9872 2002.03.15 4 S32W18 0030 DSO 9873 2002.03.17 17 S17W09 0120 DAO Total number of sunspots: 64 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 2001.01 166.6 95.6 108.7 (-3.3) 2001.02 146.6 80.6 104.1 (-4.6) 2001.03 177.7 113.5 104.8 (+0.7) 2001.04 177.7 107.7 107.6 (+2.8) 2001.05 147.1 96.6 108.7 (+1.1) 2001.06 173.0 134.0 109.8 (+1.1) 2001.07 131.3 82.2 111.7 (+1.9) 2001.08 162.9 106.8 113.6 (+1.8) 2001.09 233.2 150.7 (113.7 predicted, +0.1) 2001.10 207.6 125.6 (111.7 predicted, -2.0) 2001.11 210.6 106.5 (110.2 predicted, -1.5) 2001.12 235.1 131.8 (106.9 predicted, -3.3) 2002.01 226.6 113.9 (103.3 predicted, -3.6) 2002.02 205.0 108.0 (101.9 predicted, -1.4) 2002.03 181.0 (1) 81.5 (2) (97.6 predicted, -4.3) 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]