Solar Terrestrial Activity Report [Image] Last update April 11, 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 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 10. Solar wind speed ranged between 407 and 563 km/sec under the influence of a coronal stream. Solar flare activity was low. Solar flux was 177.8, the planetary A index was 20 (3-hour K indices: 4444 3234, Boulder K indices: 4444 3223). Region 8936 is rotating over the west limb, as is region 8939. Regions 8944 and 8945 decayed into spotless plage. Region 8948 appears to be slowly decaying, however, it still has a magnetic delta configuration and could produce minor M flares. Region 8949 was quiet and stable, as was region 8951. Region 8952 decayed into spotless plage. Region 8953 was quiet and stable. New region 8954 rotated into view at the northeast limb. New region 8955 rotated into view at the southeast limb. New region 8956 emerged near the northeast limb. New region 8957 emerged near region 8948. Flares and CMEs A total of 7 C flares were recorded on April 10. Region 8948 produced a C8.1/1N flare at 00:27, a C1.6 flare at 07:55, a C2.1 flare at 20:20 and a C8.2/1N flare at 21:10 UTC. April 9: Region 8948 produced an M3.1/2B flare at 23:42 UTC. The event was accompanied by a moderately strong type II sweep and occurred right over the central meridian. A slow moving full halo CME was observed in LASCO images. The CME has a fairly high probability of impacting Earth on April 13 but will probably not cause a significant disturbance, unsettled to minor storming is expected. The background x-ray flux is at the class B8 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 11-12. A CME will likely impact Earth on April 13 causing unsettled to active conditions, perhaps with minor storm intervals. 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 8936 20000329 1 S16W88 0030 HRX 8938 20000330 S10W87 plage 8939 20000330 1 N23W82 0040 HSX 8940 20000330 N15W82 plage 8944 20000401 N08W48 plage 8945 20000401 S23W42 plage 8947 20000403 N23W89 plage 8948 20000404 48 S15W12 0170 EAI beta-gamma-delta 8949 20000405 6 S19E13 0130 CSO 8951 20000407 1 N11E39 0100 HSX 8952 20000407 S23E09 plage 8953 20000409 9 S17E56 0060 DSO 8954 20000410 2 N31E66 0000 AXX 8955 20000410 1 S22E77 0040 HSX 8956 20000410 1 N11E52 0000 AXX 8957 20000410 5 S12W14 0020 DAO Total number of sunspots: 75 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 2000.04 194.7 (1) 69.1 (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]