Solar Terrestrial Activity Report [Image] Last update March 29, 2000 at 04:40 UTC. Minor update posted at 11:16 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 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update March 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update March 2, 2000)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet on March 28. Solar wind speed ranged between 279 and 455 km/sec. Solar flare activity was moderate. Solar flux was 200.9, the planetary A index was 5 (3-hour K indices: 2122 1221, Boulder K indices: 2212 1210). Region 8915 was quiet and is rotating over the west limb. Region 8916 was quiet and stable and will rotate off the visible disk on March 30. Region 8921 developed slowly and could produce a minor M flare. Region 8923 decayed into spotless plage. Region 8924 developed a weak magnetic delta configuration and could produce an M flare. Region 8925 developed a weak magnetic delta as well and has M class flare potential. Region 8926 was mostly quiet following the M flare early in the day. Another M flare is possible as the region rotates off the visible disk today. Region 8927 was mostly unchanged and will rotate over the west limb on March 30. Region 8928 was quiet and stable, as were regions 8931 and 8932. Regions 8933 and 8934 developed slowly and were quiet. Very active regions are at the southeast limb and the northeast limb and will rotate into view within 1-2 days, both regions appear to be capable of M class flaring. Comment added at 11:16 UTC on March 29: What may have been a solar wind shock was observed at ACE at 06:36 UTC. Solar wind speed increased rapidly from 300 to 400 km/sec, however, there was no change in the total field strength of the interplanetary magnetic field. Solar wind speed has since increased to above 600 km/sec. At 11:15 UTC wind speed increased abruptly from 550 to 690 km/sec, this time with noticable changes in other solar wind parameters as well. The source of the current disturbance is probably region 8921, the flare and coronal mass ejection which occurred late on March 25. The interplanetary magnetic field has so far been mostly northerly with a few weak southerly excursions. A significant southward swing could cause the geomagnetic field to become unsettled to active, perhaps even with isolated minor storm intervals. Flares and CMEs A total of 12 C flares and 1 M flare were recorded on March 28. Region 8926 produced an M3.1 flare at 01:37 UTC and a C4.5/1F flare at 02:16 UTC. Nearly all of the remaining C flares were produced by the regions at the east limb, including a C8.7 flare at 19:14 UTC. 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 quiet to unsettled on March 29-30. There is only a minor chance of a CME impact today, should such an impact occur unsettled to active conditions will be likely. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to good. 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 8915 20000316 1 N22W78 0150 HSX 8916 20000317 4 N13W68 0130 DSO 8919 20000319 S21W61 plage 8920 20000320 N24W49 plage 8921 20000320 25 S17W30 0140 DAI 8922 20000321 N12W35 plage 8923 20000322 S26W37 plage 8924 20000323 28 N10W01 0290 DAI beta-gamma-delta 8925 20000323 20 S17E08 0270 DKI beta-gamma-delta 8926 20000323 5 S10W84 0080 DSO 8927 20000323 12 N17W66 0050 DSO 8928 20000324 1 N18E02 0040 HSX 8929 20000325 S25E14 plage 8930 20000325 S36E15 plage 8931 20000326 4 S14E21 0020 DSO 8932 20000326 1 S14E46 0040 HSX 8933 20000327 7 N16E20 0020 ESO 8934 20000327 4 N21E39 0020 CRO Total number of sunspots: 112 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.02 141.9 66.1 84.6 (+2.0) 1999.03 126.3 69.1 83.8 (-0.8) 1999.04 117.2 63.9 85.4 (+1.6) 1999.05 148.4 106.3 90.4 (+5.0) 1999.06 169.8 137.7 93.0 (+2.6) 1999.07 165.6 113.5 94.4 (+1.4) 1999.08 170.7 93.7 97.5 (+3.1) 1999.09 135.7 71.5 (102.6 predicted, +5.1) 1999.10 164.8 116.4 (107.7 predicted, +5.1) 1999.11 191.5 132.7 (110.2 predicted, +2.5) 1999.12 169.8 86.4 2000.01 158.1 90.2 2000.02 174.1 112.3 2000.03 207.6 (1) 179.7 (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]