Solar Terrestrial Activity Report [Image] Last update April 5, 2002 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, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April, 2002)] [Historical solar and geomagnetic data charts 1954-2001 (last update January 12, 2002)] Recent development The geomagnetic field was quiet to unsettled on April 4. Solar wind speed ranged between 426 and 558 km/sec, generally decreasing throughout the day. Solar flare activity was high. Solar flux was 216.2, the planetary A index was 8 (3-hour K indices: 2123 3322, Boulder K indices: 2123 3200). Region 9884 decayed further and could become spotless before rotating over the southwest limb on April 6. Region 9885 decayed further and was quiet. A minor M class flare is possible. Region 9886 developed slowly and now has a magnetic delta structure in the leading spots section. An M class flare is possible. Region 9887 decayed slowly in the intermediate spots section but remains capable of producing a major flare. No mixing of magnetic polarities is evident at this time. Region 9888 was mostly unchanged and may be capable of generating a minor M class flare. Region 9889 reemerged briefly with a couple of spots in the morning, no spots were visible by early afternoon. Region 9891 decayed into spotless plage. Region 9892 decayed and could soon become spotless. Region 9893 developed at a moderate pace and could produce an M class flare. Early on April 5 a new region is emerging in the northern hemisphere right over the central meridian. A large region is rotating into view at the southeast limb, this is likely old region 9866. Flares and CMEs A total of 59 C and 2 M class events were recorded on April 4. Region 9893 produced a C2.8 flare at 03:36 and a C2.0 flare at 21:58 UTC. Region 9888 generated a C3.0 flare at 06:54 UTC. Region 9885 was the source of a C3.0 flare at 14:36 UTC. A C9.8 flare was recorded at 04:30 UTC from an unspotted area in the southeast quadrant near the southeast limb. The associated CME is not likely to be geoeffective. An M1.4 flare at 10:48 appears to have had its origin behind the southwest limb. An impulsive M6.1 flare was recorded at 15:32 with its source from just behind the southeast limb, likely in old region 9866. A fast CME was observed in association with this flare. The background x-ray flux is at the class C1 level. Coronal holes A small coronal hole in the southern hemisphere may have been in a geoeffective position on April 2 and could cause a minor increase in geomagnetic activity on April 5. Another small coronal hole in the southern hemisphere could rotate into a geoeffective position on April 6. Forecast The geomagnetic field is expected to be mostly quiet to unsettled on April 5-7. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor and slowly improving. 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 9883 2002.03.23 N07W88 plage 9884 2002.03.27 1 S17W67 0030 HSX 9885 2002.03.27 27 N13W39 0510 EHI 9886 2002.03.29 16 N13W24 0100 DSO beta-gamma-delta 9887 2002.03.29 26 N02W16 0720 EKI 9888 2002.03.29 11 S12W06 0180 DAO 9889 2002.03.31 2 S20W06 0000 BXO now spotless 9890 2002.04.02 S15W75 plage 9891 2002.04.02 S08W35 plage 9892 2002.04.02 5 N09E34 0030 CSO 9893 2002.04.03 8 N18E64 0250 EHO beta-gamma Total number of sunspots: 96 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.8 2001.02 146.6 80.6 104.0 (-4.7) 2001.03 177.7 113.5 104.8 (+0.8) 2001.04 177.7 107.7 107.5 (+2.7) 2001.05 147.1 96.6 108.6 (+1.1) 2001.06 173.0 134.0 109.8 (+1.2) 2001.07 131.3 82.2 111.7 (+1.9) 2001.08 162.9 106.8 113.6 (+1.8) 2001.09 233.2 150.7 114.1 (+0.5) 2001.10 207.6 125.5 (112.7 predicted, -1.4) 2001.11 210.6 106.5 (111.5 predicted, -1.2) 2001.12 235.1 132.2 (108.1 predicted, -3.4) 2002.01 226.6 113.9 (104.8 predicted, -3.3) 2002.02 205.0 108.0 (103.4 predicted, -1.4) 2002.03 179.5 98.1 (99.1 predicted, -4.3) 2002.04 209.7 (1) 26.3 (2) (93.2 predicted, -5.9) 1) Running average based on the daily 20:00 UT solar flux value at 2800 MHz. 2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number is typically 25-45% 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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News]