Solar Terrestrial Activity Report [Image] Last update April 6, 2000 at 03:50 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 5. Solar wind speed ranged between 347 and 434 km/sec. Solar flare activity was low. Solar flux was 194.4, the planetary A index was 11 (3-hour K indices: 4422 3332, Boulder K indices: 3421 1312). Regions 8931 and 8932 were quiet and stable, region 8931 is rotating over the west limb. Region 8933 was quiet and is rotating over the west limb. Region 8935 was quiet and stable. 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 quiet and stable, as were regions 8942, 8943, 8944 and 8945. Region 8948 was quiet and stable but has minor M class flaring potential. New region 8949 rotated into view at the southeast limb. New region 8950 emerged near the northwest limb, the region is spotless early on April 6. An interesting region is approaching the northeast limb. Flares and CMEs Only 1 C flare was recorded on April 5, it was optically uncorrelated. Region 8948 was the source of an M1.8 flare at 02:29 on April 6. A moderately strong type II sweep accompanied the event. 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 B9-C1 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be quiet to unsettled on April 6 with a chance of isolated active intervals. 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. 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 8931 20000326 5 S14W86 0070 DSO 8932 20000326 10 S12W61 0050 DAI 8933 20000327 8 N18W84 0290 FAO 8934 20000327 N21W67 plage 8935 20000329 1 S06W63 0010 HSX 8936 20000329 22 S15W21 0210 DAI beta-gamma 8938 20000330 S04W22 plage 8939 20000330 8 N23W12 0060 CSO 8940 20000330 4 N12W12 0010 BXO 8942 20000331 1 S10W53 0010 HRX 8943 20000331 4 N22W47 0090 CSO 8944 20000401 2 N08E18 0040 HAX 8945 20000401 6 S19E20 0040 DSO 8946 20000403 S24W36 plage 8947 20000403 N23W24 plage 8948 20000404 7 S15E56 0110 DAO beta-gamma 8949 20000405 2 S18E76 0050 HSX 8950 20000405 1 N18W64 0000 AXX Total number of sunspots: 81 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 2000.04 211.7 (1) 41.5 (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]