Solar Terrestrial Activity Report [Image] Last update February 21, 2000 at 04:35 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update February 3, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update February 3, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 3, 2000)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet to unsettled on February 20. Solar wind speed ranged between 325 and 452 km/sec. A solar wind shock was observed at ACE near 20:45 UTC. Although the interplanetary magnetic field was mostly moderately to strongly southwards for several hours following the CME impact at 21:40, the effects on the geomagnetic field was much smaller than was expected. Currently solar wind densities are very high and the main body of the disturbance may not yet have arrived. Solar flare activity was moderate. Solar flux was 153.3, the planetary A index was 5 (3-hour K indices: 1031 0023, Boulder K indices: 0122 1113). Region 8869 developed further and is capable of producing a major flare. Region 8870 was quiet and stable, as was region 8872 (which is spotless early on Feb. 21). Region 8875 is developing and could produce C flares today. Should further development take place minor M flares will become possible. Region 8876 was quiet and stable, the region is spotless early on Feb.21. Region 8878 rotated off the visible disk. Region 8879 was quiet and stable and has only a single, very large sunspot. New region 8880 emerged in the southwest quadrant near the limb. An active region at the northeast limb is rotating into view. Another active region at the southeast limb is rotating into view as well, this region could produce further M flares. Flares and CMEs 11 C flares and 1 M flare were recorded on February 20. Region 8869 produced many C flares including a C8.5/1N flare at 00:57 UTC, a C4.0 flare at 04:20 UTC and a C4.9 flare at 10:26 UTC. The region rotating onto the disk at the southeast limb produced an M2.4 flare at 22:07 UTC, it was accompanied by a moderately strong type II sweep. The background x-ray flux is at the class B7 level. Coronal holes A trans equatorial coronal hole will rotate into a geoeffective position on February 21-25 and start a geomagnetic disturbance on Feb.24. This coronal hole is smaller than it has been over the last several months and is probably decaying. Forecast The geomagnetic field is expected to be unsettled to major storm on February 21. Quiet to active is expected for February 22. A coronal stream will cause unsettled to minor storm conditions on February 24-26. 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 no. Location at region numbered sunspots midnight Area Classification Comment 8869 41 S20W61 0480 FAI beta-gamma 8870 1 N18W52 0050 HAX 8872 1 S31W34 0000 AXX 8874 S09W26 plage 8875 11 S22W13 0050 CAO 8876 3 S11W04 0010 BXO 8877 S22W16 plage 8879 20000217 1 N22E37 0240 HSX 8880 20000220 3 S08W69 0010 BXO Total number of sunspots: 61 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.01 140.6 62.4 82.6 (+4.8) 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 (97.4 predicted, + 3.0) 1999.09 135.7 70.9 (102.4 predicted, +5.0) 1999.10 164.8 116.4 (107.5 predicted, +5.1) 1999.11 191.5 132.7 1999.12 169.8 86.4 2000.01 158.1 90.2 2000.02 162.8 (1) 107.0 (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]