Solar Terrestrial Activity Report [Image] Last update May 21, 2000 at 04:10 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update May 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update May 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update May 2, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update April 12, 2000)] Recent development The geomagnetic field was quiet on May 20. Solar wind speed ranged between 411 and 570 km/sec. Solar flare activity was low. Solar flux was 245.6, the planetary A index was 6 (3-hour K indices: 2212 2222, Boulder K indices: 2222 2222). Region 8996 was mostly unchanged and will likely continue to produce C flares. The potential for a major flare still exists. Region 8998 decayed slowly, the region will likely continue to produce C flares and has a change of producing isolated M flares. Region 8999 developed slowly and could produce further C flares. Region 9002 did not change significantly and remains capable of producing a major flare. Region 9004 developed quickly. The two penumbras containing the positive and negative polarity spots merged into a large penumbra setting up a magnetic delta configuration. The region could be capable of major flaring but has been mostly quiet so far. Region 9009 was quiet and stable. Region 9010 seems to be developing slowly and could produce further C flares. Region 9011 was quiet and stable, as was region 9012. New region 9013 emerged near the southwest limb. New region 9014 emerged at a high latitude in the southeast quadrant. A very strong noise storm has been in progress early on May 21. Flares and CMEs A total of 9 C flares were observed on May 20. Region 8998 produced a C5.0 flare at 00:48, a C3.6/1F flare at 03:24 and an interesting C7.6/1N flare at 05:35 UTC. The latter event was accompanied by strong type II sweeps and a moderately strong type IV sweep. A partial halo coronal mass ejection was observed covering the southeast limb, the south pole, the southwest limb as well as part of the northwest limb. There is a fairly good chance of a terrestrial impact from this CME. Region 9004 generated a C2.7 flare at 04:38 UTC. Region 9002 produced a C4.2 flare at 17:05 UTC. Region 8996 was the source of a C2.1 flare at 20:22 and a C2.8 flare at 21:15 UTC. Region 8999 generated a C2.5 flare at 21:56 UTC while region 9010 managed a C2.6 flare at 22:34 UTC. The background x-ray flux is at the class C1-C2 level. Coronal holes A coronal hole in the northern hemisphere may have been too far to the north to be geoeffective when it rotated over the central meridian on May 18. Forecast The geomagnetic field is expected to be quiet to unsettled on May 21-22. A coronal stream could arrive today and cause unsettled and active intervals. A CME could impact Earth on May 23 causing 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 8991 20000508 N16W79 plage 8992 20000509 N10W70 plage 8996 20000511 44 S21W35 0870 EKC beta-gamma 8997 20000511 S17W45 plage 8998 20000512 32 S12W22 0420 EAC beta-gamma 8999 20000513 9 N19W22 0020 BXO 9000 20000513 N10W80 plage 9002 20000514 49 N19E04 0720 FKI beta-gamma 9004 20000515 14 N12W06 0520 DKC beta-delta 9005 20000516 S18W85 plage 9007 20000517 S42W27 plage 9008 20000517 S30E12 plage 9009 20000518 2 S14E42 0030 HSX 9010 20000518 11 N21E42 0090 CAO 9011 20000519 2 N17E53 0240 HAX 9012 20000519 4 S29W36 0010 BXO 9013 20000520 4 S06W61 0000 BXO 9014 20000520 1 S43E21 0010 AXX Total number of sunspots: 172 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.04 117.2 63.9 85.5 (+1.7) 1999.05 148.4 106.3 90.5 (+5.0) 1999.06 169.8 137.7 93.1 (+2.6) 1999.07 165.6 113.5 94.5 (+1.4) 1999.08 170.7 93.7 97.4 (+2.9) 1999.09 135.7 71.5 102.3 (+4.8) 1999.10 164.8 116.7 107.7 (+5.4) 1999.11 191.5 133.2 (110.4 predicted, +2.7) 1999.12 169.8 84.6 (110.2 predicted, -0.2) 2000.01 158.1 90.2 (111.5 predicted, +1.3) 2000.02 174.1 112.3 (114.9 predicted, +3.4) 2000.03 208.2 138.2 (118.7 predicted, +3.8) 2000.04 184.2 125.3 2000.05 189.1 (1) 128.1 (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]