Solar Terrestrial Activity Report [Image] Last update May 21, 2002 at 03:40 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 3, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update May 3, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update May 3, 2002)] [Historical solar and geomagnetic data charts 1954-2002 (last update April 13, 2002)] Recent development The geomagnetic field was quiet to active on May 20. Solar wind speed ranged between 397 and 566 km/sec. A solar wind shock was observed at SOHO at 02:56 UTC. Solar wind speed increased suddenly from 420 to 560 km/sec. The source of this shock was likely a CME related to a large filament eruption in the southeast quadrant early on May 17. Solar flare activity was high. Solar flux was 171.3, the planetary A index was 14 (3-hour K indices: 1323 3433, Boulder K indices: 2323 2432). Region 9948 decayed slowly and quietly. There is an emerging positive polarity area at the southwestern edge of the large penumbra. If this development continues the region could soon acquire a magnetic delta structure. A minor M class flare is possible. Region 9950 decayed and was spotless by the end of the day. Regions 9954 and 9955 decayed slowly and quietly. Region 9957 decayed further and continued to fragment into more penumbrae. Early on May 21 it appears as if the magnetic delta structures have disappeared. The region is still large and could produce a major flare. Region 9958 was quiet and stable. Region 9960 developed slowly and has a magnetic delta structure. A minor m class flare is possible. Region 9961 developed very quickly during the first half of the day and at one time had three magnetic delta structures, one each in the leading, central and trailing spots sections. The magnetic delta in the leading spots cannot be seen anymore early on May 21, but the region is still sufficiently complex to produce another major flare. New region 9962 one day's rotation east of region 9960 was finally numbered by SEC/NOAA. New region 9963 rotated into view at the northeast limb. This region appears to have a magnetic delta structure. The negative polarity area in this region is quite strong and extends southwards from the location of the spots. An M class flare may be possible. Flares and CMEs A total of 6 C, 2 M and 1 X class events were recorded on May 20. Region 9961 was the only flare producer of the day. A C3.9 flare was recorded at 08:05, an impulsive M4.7 flare at 10:29, a major impulsive M5.0 flare at 10:53, a major impulsive X2.1/2N flare at 15:27 (with an associated narrow CME off the southeast limb), a C4.1/1F flare at 18:20, a C1.8 flare at 19:51 and a C3.0 flare at 20:24 UTC. A filament eruption near the southwest limb during the early evening of May 19 was associated with a partial halo CME appearing first in LASCO C2 images at 20:26 UTC. The CME was likely not wide enough to be geoeffective. 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 May 21. The size of this coronal hole has shrunk considerably over the last rotation but could still cause unsettled to active geomagnetic conditions on May 24-25. Forecast The geomagnetic field is expected to be quiet to unsettled on May 21 with a possibility of one or two active intervals. Quiet to unsettled is likely on May 22-23. 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 9948 2002.05.10 2 S21W57 0320 HKX 9950 2002.05.11 1 S04W77 0010 AXX now spotless 9951 2002.05.12 N12W38 plage 9954 2002.05.15 6 S20E01 0110 DAO 9955 2002.05.15 1 S15E02 0020 HSX 9956 2002.05.16 S08W56 plage 9957 2002.05.16 37 N09E22 0830 EKC beta-gamma 9958 2002.05.17 2 N04E09 0090 HSX 9959 2002.05.17 N10W30 plage 9960 2002.05.18 6 N14E46 0140 DAO beta-gamma-delta 9961 2002.05.19 14 S22E62 0480 EAI beta-gamma-delta 9962 2002.05.20 1 N15E59 0020 HRX beta-delta? 9963 2002.05.20 1 N17E75 0120 HAX too few spots, classification wrong Total number of sunspots: 71 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 2001.04 177.7 107.7 107.5 (+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) 2001.10 207.6 125.5 114.0 (-0.1) 2001.11 210.6 106.5 (114.7 predicted, +0.7) 2001.12 235.1 132.2 (112.5 predicted, -2.2) 2002.01 226.6 113.9 (109.8 predicted, -2.7) 2002.02 205.0 108.0 (108.4 predicted, -1.4) 2002.03 179.5 98.1 (104.2 predicted, -4.2) 2002.04 189.8 120.4 (98.3 predicted, -3.9) 2002.05 175.5 (1) 127.7 (2) (93.8 predicted, -4.5) 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]