Solar Terrestrial Activity Report [Image] Last update April 22, 2002 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, 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 1954-2002 (last update April 13, 2002)] Recent development The geomagnetic field was quiet to unsettled on April 21. Solar wind speed ranged between 425 and 542 km/sec. Solar flare activity was high. Solar flux was 173.4, the planetary A index was 7 (3-hour K indices: 3221 2223, Boulder K indices: 2221 2323). Region 9906 rotated out of view at the southwest limb. The region may be capable of producing another major proton event before rotating too far behind the limb. Region 9907 decayed further and was spotless by the end of the day. Region 9909 decayed slowly and quietly. Region 9910 decayed further and lost most of its trailing spots. Region 9912 developed slowly and could produce minor M class flares. Region 9913 decayed and was spotless around noon, then reemerged with a few spots. Region 9914 developed slowly and quietly. New region 9915 emerged near the northeast limb. This region is fairly active and could produce C class flares. New region 9916 rotated into view at the southeast limb. The above 10 MeV proton event which started soon after the major flare in region 9906 has so far peaked near 2500 pfu just before midnight on April 21. Flares and CMEs A total of 4 C and 1 X class events were recorded on April 21. Region 9906 produced a major long duration X1.6 proton event which began at 00:43 and peaked at 01:51 UTC. Strong type II and IV radio sweeps were recorded in association with this event. This event included a large filament eruption in the southwest quadrant as well. A very large, very wide and extremely fast CME was observed in LASCO C3 images. The CME became nearly a full halo CME with only a part of the southeast limb not covered. The outer edges of this monster solar storm could hit the Earth on April 22, probably during the latter half of the day, and cause a major geomagnetic storm. The background x-ray flux is at the class B8 level. Coronal holes A recurrent trans equatorial coronal hole will rotate into a geoeffective position on April 24-25. This coronal hole appears to have shrunk in size over the last rotation. Forecast The geomagnetic field is expected to be unsettled to severe storm on April 22-23. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is useless. 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 region numbered sunspots at Area Classification Comment midnight 9906 2002.04.11 14 S14W90 0330 EAI beta-gamma 9907 2002.04.11 2 S03W63 0020 CRO now spotless 9909 2002.04.14 2 N07W24 0050 HSX 9910 2002.04.15 13 S20W33 0100 CAO 9911 2002.04.18 S13W17 plage 9912 2002.04.18 21 N10W12 0270 DAI beta-gamma 9913 2002.04.19 8 S17W02 0010 BXO 9914 2002.04.19 5 N04E44 0070 CAO 9915 2002.04.21 1 N11E54 0030 HRX 9916 2002.04.21 4 S17E71 0150 DAO Total number of sunspots: 70 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 (113.3 predicted, -0.8) 2001.11 210.6 106.5 (112.7 predicted, -0.6) 2001.12 235.1 132.2 (109.3 predicted, -3.4) 2002.01 226.6 113.9 (106.0 predicted, -3.3) 2002.02 205.0 108.0 (104.6 predicted, -1.4) 2002.03 179.5 98.1 (100.4 predicted, -4.2) 2002.04 201.5 (1) 145.2 (2) (94.5 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]