Solar Terrestrial Activity Report [Image] Last update March 21, 2000 at 04:15 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 to unsettled on March 20. Solar wind speed ranged between 341 and 379 km/sec. Solar flare activity was moderate. Solar flux was 210.3, the planetary A index was 8 (3-hour K indices: 1013 3222, Boulder K indices: 1112 2211). Region 8906 was quiet and rotated off the visible disk early today. Region 8909 decayed and was quiet, the region is spotless early on March 21. Region 8910 developed further and has a strong magnetic delta inside the very large main penumbra. Major flares, including an X flare, are possible. Region 8913 developed at a moderate pace and could produce minor M class flares. Region 8915 was quiet and stable. Region 8916 developed further and could generate minor M class flares. Region 8917 developed further and could host an M class flare. Region 8918 is still developing fairly quickly and has minor M class flaring potential. Region 8919 decayed into spotless plage. New region 8920 emerged in the northeast quadrant. New region 8921 rotated partly into view at the southeast limb. Flares and CMEs A total of 9 C flares and 2 M flares were recorded on March 20. Region 8910 produced a C2.6 flare at 07:02, a C8.4 flare at 10:59, a C2.1 flare at 18:16 and an impulsive M2.4/2B flare at 16:44 UTC. Region 8918 generated a C2.7 flare at 14:58 UTC. The most interesting event of the day was an M2.2/2B flare at 08:34 UTC. It was accompanied by moderately strong type II and IV sweeps and an impressive coronal mass ejection off the southeast limb. Region 8921 or another nearby region was the source of the event. A filament eruption began in the southwest quadrant at 09:48 UTC and moved eastwards to the central meridian. Another filament eruption in the same area was triggered by a sub flare in region 8909 at 12:34 UTC. The background x-ray flux is at the class C1-C2 level. Coronal holes The large coronal hole that has been around for several months has split into three smaller coronal holes. One is in the northern hemisphere and was in a geoeffective position on March 19, another (fairly small and closing because of development in region 8913) is in the southern hemisphere and was in a geoeffective position on March 20. The third, and largest remaining part, is trans equatorial and should rotate into a geoeffective position on March 21-22. Forecast The geomagnetic field is expected to be quiet to unsettled on March 21. A coronal hole related disturbance is likely to start on March 22 and could cause unsettled to active intervals until March 25, occasional minor storm intervals are possible. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair. 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 8906 20000308 4 S16W88 0230 EAO 8908 20000309 S23W70 plage 8909 20000311 1 S28W41 0000 AXX 8910 20000312 55 N13W35 0680 EKC beta-gamma-delta 8912 20000314 N15W80 plage 8913 20000314 33 S16W11 0210 EAI 8914 20000316 N16W47 plage 8915 20000316 2 N23E24 0200 HSX 8916 20000317 16 N13E40 0250 EHO beta-gamma 8917 20000318 14 N19W08 0160 DAO 8918 20000319 12 N32W27 0060 DSO beta-gamma 8919 20000319 S22E45 plage 8920 20000320 1 N24E55 0010 AXX 8921 20000320 2 S15E71 0030 CSO Total number of sunspots: 140 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 2000.03 204.1 (1) 120.8 (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]