Solar Terrestrial Activity Report [Image] Last update May 20, 2002 at 04:00 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 to minor storm on May 19. Solar wind speed ranged between 372 and 518 km/sec. A solar wind shock was observed at SOHO at 02:56 UTC on May 20. Solar wind speed increased suddenly from 420 to 560 km/sec. The interplanetary magnetic field has been mostly northwards since the shock. 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 low. Solar flux was 170.9, the planetary A index was 18 (3-hour K indices: 3452 3322, Boulder K indices: 4452 2112). Region 9945 rotated out of view at the southwest limb early in the day, but was included by SEC/NOAA in their spots summary. Region 9948 decayed slowly and quietly. There is a positive polarity area at the southwestern edge of the large penumbra. A minor M class flare is possible. Region 9950 decayed further and had only a single small spot left by the end of the day. The region is likely to become spotless later today. Region 9954 decayed slowly and quietly. Region 9955 was quiet and stable. Region 9957 continued to fragment slowly. Some slow development was observed in the northernmost spot section. The region still has a magnetic delta structure and may be capable of producing a major flare. Region 9958 was quiet and stable. Region 9960 was mostly unchanged and could produce minor M class flares. New region 9961 rotated into view at the southeast limb. This region has minor M class flare potential and appears to have a magnetic delta structure in the trailing penumbra. SEC/NOAA failed to number a small region which rotated into view at the northeast limb. Flares and CMEs A total of 13 C class events were recorded on May 19. Region 9957 produced a C1.1 flare at 06:49 and a C2.3 flare at 16:22 UTC. Region 9961 generated a C2.2 flare at 17:11 UTC. The remainder of the flares were optically uncorrelated. The background x-ray flux is at the class C1 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 and development in regions 9957 and 9958 could cause a further reduction in size before the coronal hole is in a geoeffective position. Forecast The geomagnetic field is expected to be quiet to minor storm on May 20 and quiet to unsettled on May 21-22. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 9945 2002.05.07 3 S01W95 0050 CAO 9946 2002.05.08 S06W82 plage 9948 2002.05.10 1 S21W44 0330 HKX 9950 2002.05.11 1 S04W64 0050 HSX area too large, should be 0010 9951 2002.05.12 N12W25 plage 9954 2002.05.15 6 S22E14 0100 DAO 9955 2002.05.15 2 S14E15 0030 HSX 9956 2002.05.16 S08W43 plage 9957 2002.05.16 38 N08E34 0830 EKC beta-gamma-delta 9958 2002.05.17 2 N04E24 0090 CSO 9959 2002.05.17 N10W17 plage 9960 2002.05.18 7 N14E58 0140 DAO beta-gamma-delta 9961 2002.05.19 5 S22E76 0110 DAO beta-gamma-delta Total number of sunspots: 65 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) 2002.05 175.7 (1) 122.2 (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]