Solar Terrestrial Activity Report [Image] Last update April 2, 2000 at 04:55 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update April 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April 2, 2000)] [Historical solar and geomagnetic data charts 1954-1999] Recent development The geomagnetic field was quiet to active on April 1. Solar wind speed ranged between 363 and 451 km/sec. Solar flare activity was low. Solar flux was 222.9, the planetary A index was 14 (3-hour K indices: 3312 3443, Boulder K indices: 2322 2343). Region 8924 still has a weak magnetic delta configuration and could produce a minor M class flare. Region 8925 decayed further and could generate occasional C flares. Region 8928 was quiet and stable. Region 8929 reemerged with a single spot. Regions 8931, 8932 and 8933 are all developing slowly and are capable of C class flaring. Region 8935 was mostly unchanged and quiet. The region could produce a minor M class flare. Region 8936 developed slowly and has M class flare potential. Region 8938 was quiet and stable. Region 8939 developed slowly and could produce minor M flares. Region 8940 was quiet and stable, as was region 8942. Region 8943 developed slowly and could produce C flares. New region 8944 rotated partly into view at the northeast limb. New region 8945 rotated partly into view at the southeast limb. Flares and CMEs A total of 8 C flares were recorded on April 1. Region 8936 produced a C9.5 flare at 05:17, a long duration M1.2 event at peaking at 06:52 UTC (this event was accompanied by a partial halo coronal mass ejection extending from the south pole to the northeast limb), an M1.0 flare at 07:55, a C8.5 flare at 09:32, a C6.5 flare at 11:46, a C1.8 flare at 22:47 and a C1.9 flare at 23:42 UTC. Region 8939 generated a C2.7 flare at 10:04, an impulsive M4.1 flare at 10:19 UTC (accompanied by a weak type IV sweep), an M1.8 flare at 13:18 and an M1.2 flare at 16:55 UTC. Region 8925 was the source of an M2.0/1N flare at 19:01 UTC. March 31: An interesting filament eruption occurred near region 8934 over the central meridian starting just after 10h UTC. This event may have produced a geoeffective CME. The background x-ray flux is at the class C1 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to active on April 2-3. On April 3 a CME could impact Earth and cause unsettled to minor storm conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 8921 20000320 S17W82 plage 8922 20000321 N16W83 plage 8924 20000323 14 N10W55 0350 DSI beta-gamma-delta 8925 20000323 11 S18W44 0080 EAO beta-gamma 8928 20000324 1 N20W52 0010 HSX 8929 20000325 1 S22W38 0000 AXX 8930 20000325 S36W37 plage 8931 20000326 17 S14W33 0090 EAO 8932 20000326 7 S13W06 0060 CSO 8933 20000327 9 N16W30 0060 DSO 8934 20000327 N21W15 plage 8935 20000329 13 S07W07 0170 DAO 8936 20000329 30 S15E33 0300 DKC beta-gamma 8937 20000329 N26E25 plage 8938 20000330 1 S06E30 0010 AXX 8939 20000330 8 N23E43 0130 DAO 8940 20000330 1 N14E38 0020 HRX 8941 20000330 N25E28 plage 8942 20000331 2 S12E06 0020 HRX 8943 20000331 8 N23E07 0030 BXO 8944 20000401 1 N08E70 0050 HSX 8945 20000401 3 S17E72 0050 BXO Total number of sunspots: 127 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 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 71.5 102.3 (+4.8) 1999.10 164.8 116.4 (108.6 predicted, +6.3) 1999.11 191.5 132.7 (112.3 predicted, +3.7) 1999.12 169.8 86.4 (111.9 predicted, -0.4) 2000.01 158.1 90.2 (112.7 predicted, +0.8) 2000.02 174.1 112.3 (116.2 predicted, +3.5) 2000.03 208.2 138.2 2000.04 222.9 (1) 9.6 (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]