Solar Terrestrial Activity Report [Image] Last update April 5, 2000 at 03:55 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 minor storm on April 4 with a few stations reporting major storm during the 00-03h UTC interval. Solar wind speed ranged between 361 and 433 km/sec. The source of the current disturbance is likely a filament eruption observed near region 8934 over the central meridian on March 31. Solar flare activity was moderate. Solar flux was 206.7, the planetary A index was 21 (3-hour K indices: 5421 4344, Boulder K indices: 6420 3433). Region 8925 decayed into spotless plage. Regions 8931 and 8932 were quiet and stable. Region 8933 developed quickly and has a magnetic delta configuration. A major flare is possible before the region departs the visible disk on April 6. Region 8935 was quiet and stable. Region 8936 was mostly unchanged and still has M class flare potential. Region 8939 did not change significantly and was quiet. Region 8940 was quiet and stable, as were regions 8942, 8943, 8944 and 8945. Regions 8946 and 8947 decayed into spotless plage. New region 8948 (old region 8906) rotated into view at the southeast limb. The region could produce further minor M class flares. Flares and CMEs A total of 4 C flares and 1 M flare were recorded on April 4. Region 8948 produced an M1.0 flare 01:32 UTC. Region 8933 was the source a C9.7/2F proton flare peaking at 15:41 UTC. The flare triggered a filament eruption in a large filament to the east of the region. The 10 MeV proton flux has reached 28 pfu but could still increase further, this will likely result in minor radio signal absorption over polar paths. A wide and fast full halo CME was observed following the flare. April 4: Region 8933 (and a nearby large filament) produced a C9.7/2F proton flare peaking at 15:41 UTC. This event was accompanied by a strong type IV sweep and a fast and wide full halo coronal mass ejection. There is a high chance (at least 80%) of a terrestrial impact on April 7 or early on the April 8 and could result in unsettled to major storm conditions. 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 5 with a chance of an isolated minor storm interval. Quiet to unsettled is likely on April 6. A CME will likely impact Earth sometime on April 7 or early on April 8 and cause unsettled to major storm conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor to very 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 8925 20000323 S19W83 plage 8929 20000325 S22W77 plage 8930 20000325 S36W76 plage 8931 20000326 5 S14W72 0060 DSO 8932 20000326 7 S13W46 0030 DSO 8933 20000327 10 N17W70 0420 EKO beta-delta 8934 20000327 N21W54 plage 8935 20000329 1 S07W48 0020 HSX 8936 20000329 20 S16W07 0320 DAI beta-gamma-delta 8938 20000330 S04W09 plage 8939 20000330 7 N23E01 0050 CSO 8940 20000330 2 N13E00 0010 HSX 8942 20000331 1 S10W38 0010 HRX 8943 20000331 4 N22W32 0060 DAO 8944 20000401 1 N11E31 0050 HSX 8945 20000401 2 S18E33 0040 DSO 8946 20000403 S24W23 plage 8947 20000403 N23W11 plage 8948 20000404 4 S15E70 0110 CSO beta-gamma Total number of sunspots: 64 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 2000.04 216.1 (1) 34.1 (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]