Solar Terrestrial Activity Report [Image] Last update April 7, 2000 at 01:05 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 unsettled to very severe storm on April 6. Solar wind speed ranged between 364 and 631 km/sec. A severe solar wind shock was observed at ACE at 16:00 UTC and impacted Earth at 16:32 UTC. Solar wind speed increased abruptly from 380 to 620 km/sec and the interplanetary magnetic field swing very strongly southwards. After midnight and early on April 7 the IMF has been mostly weakly northwards. The source of the disturbance was a full halo CME observed on April 4. Solar flare activity was moderate. Solar flux was 177.7, the planetary A index was 56 (3-hour K indices: 3333 3678, Boulder K indices: 3333 2656). Region 8932 was quiet and stable and will rotate off the visible disk on April 8. Region 8935 was quiet and stable, the region is spotless early on April 7. Region 8936 decayed slowly and was quiet, the region still has M class flare potential. Region 8939 did not change significantly and was quiet. Region 8940 was mostly quiet and stable and has become spotless early on April 7. Region 8942 decayed into spotless plage. Regions 8943, 8944 and 8945 were quiet and stable. Region 8948 has minor M class flaring potential. Region 8949 was quiet and stable. Region 8950 was quiet and stable, the region is spotless early on April 7. Old region 8910 is at the East limb, is bright and appears to have M class flare potential. Flares and CMEs A total of 2 C flares and 1 M flare were recorded on April 6. Region 8948 produced an M1.8 flare at 02:29 UTC. It was accompanied by a moderately strong type II sweep. The background x-ray flux is at the class B9-C1 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be unsettled to severe storm on April 7. Quiet to unsettled is expected for April 8-9. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is useless. 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 8932 20000326 4 S12W74 0060 DSO 8934 20000327 N21W80 plage 8935 20000329 1 S06W76 0000 AXX 8936 20000329 14 S15W34 0160 DAI beta-gamma 8938 20000330 S04W35 plage 8939 20000330 6 N22W26 0080 CAO 8940 20000330 1 N15W30 0000 AXX 8942 20000331 S10W66 plage 8943 20000331 1 N19W63 0080 HSX 8944 20000401 1 N08E04 0040 HSX 8945 20000401 6 S20E07 0020 CRO 8946 20000403 S24W49 plage 8947 20000403 N23W37 plage 8948 20000404 8 S15E42 0070 DSO beta-gamma 8949 20000405 1 S19E68 0110 HSX 8950 20000405 2 N18W86 0000 BXO Total number of sunspots: 45 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 2000.04 206.1 (1) 46.7 (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]