Solar Terrestrial Activity Report [Image] Last update April 4, 2000 at 04:20 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 unsettled on April 3. Solar wind speed ranged between 350 and 428 km/sec. A disturbance arrived late in the day and intensified early on April 4. The source of the disturbance is likely a filament eruption observed near region 8934 on March 31. Solar flare activity was low. Solar flux was 215.4, the planetary A index was 12 (3-hour K indices: 3333 3322, Boulder K indices: 3323 3322). Region 8924 was quiet and is rotating off the visible disk. Region 8925 decayed and could become spotless before rotating over the west limb on April 5. Region 8928 decayed into spotless plage. Regions 8931 and 8932 decayed slowly and were quiet. Region 8933 developed further and may be capable of minor M class flaring. Region 8935 decayed quickly and was quiet. Region 8936 was mostly unchanged and still has M class flare potential. Region 8938 decayed into spotless plage. Region 8939 did not change significantly and will likely produce occasional C flares. Region 8940 was quiet and stable. Region 8942 decayed quickly and could become spotless today. Region 8943 decayed slowly and was quiet. Regions 8944 and 8945 were quiet and stable. New region 8946 emerged in the southwest quadrant near the central meridian. New region 8947 emerged in the northeast quadrant near the central meridian. Old region 8906 is rotating into view at the southeast limb. The region appears to have minor M class flaring potential. Flares and CMEs A total of 4 C flares were recorded on April 3, none of the flares were optically assigned to any of the numbered regions. An M1.0 flare was observed at 01:32 UTC on April 4. 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 minor storm on April 4 and quiet to unsettled on April 5-6. 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 8924 20000323 4 N12W82 0080 DAO 8925 20000323 1 S19W70 0010 AXX 8928 20000324 N21W77 plage 8929 20000325 S22W64 plage 8930 20000325 S36W63 plage 8931 20000326 11 S13W60 0070 DAO 8932 20000326 10 S12W32 0040 DSO 8933 20000327 16 N18W58 0240 DSO 8934 20000327 N21W41 plage 8935 20000329 6 S07W34 0030 CAO 8936 20000329 24 S14E06 0390 DAC beta-delta 8938 20000330 S04E04 plage 8939 20000330 11 N24E14 0080 DAO 8940 20000330 5 N14E12 0010 BXO 8942 20000331 1 S10W25 0000 AXX 8943 20000331 4 N23W20 0050 CSO 8944 20000401 1 N09E44 0060 HSX 8945 20000401 5 S18E46 0040 DSO 8946 20000403 1 S24W10 0000 AXX 8947 20000403 2 N23E02 0000 AXX Total number of sunspots: 102 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 2000.04 219.2 (1) 28.0 (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]