Solar Terrestrial Activity Report [Image] Last update May 22, 2002 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 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 21. Solar wind speed ranged between 320 and 430 km/sec. A weak solar wind shock was observed at ACE at 21:02 UTC with a sudden jump in solar wind speed from 360 to 400 km/sec. The source of this shock is undetermined. Solar flare activity was moderate. Solar flux was 185.9, the planetary A index was 14 (3-hour K indices: 3242 3334, Boulder K indices: 3131 2214). Region 9948 was mostly unchanged but the positive polarity area at the southwestern edge of the large penumbra continued to emerge slowly. This development likely contributed to the long duration event observed in the region at the end of the day. A minor M class flare is possible. Region 9954 continued to lose penumbral area, however, a couple of new spots emerged south of the main spots. Region 9955 decayed slowly and quietly. Region 9957 decayed significantly losing much penumbral area, particularly near the center of the region. The potential for a major flare is decreasing quickly. Region 9958 was quiet and stable. Region 9960 did not change much and is a compact region with magnetic delta structure. Another minor M class flare is possible. Region 9961 decayed significantly, particularly in the trailing and central spots section. Some development was observed in the leading spots section which has a magnetic delta structure. A major flare is still a possibility. Region 9962 was quiet and stable. Region 9963 lost a couple of spots in the main penumbra and gained a spot in the southern part of the trailing negative polarity area. A minor M class flare may be possible. SEC/NOAA failed to number two new regions, one located in the southeast quadrant (near S15E19 at midnight), the other one at the southeast limb. Both regions were visible by noon. Flares and CMEs A total of 5 C and 1 M class events were recorded on May 21. Region 9961 produced a C2.2 flare at 01:44 UTC. Region 9960 generated a C4.8 flare at 05:03, a C1.9 flare at 10:21 and a long duration M1.5 event peaking at 21:39 UTC. The LDE was associated with a weak type II radio sweep and a large CME mainly off the northeast limb. The CME (first observed in LASCO C2 images at 21:50 UTC) became a partial halo CME but did not appear to be wide enough to be geoeffective. Region 9963 was the source of a C3.2 flare at 17:23 UTC. Region 9948 produced a long duration C9.7 event which began at 23:14 and peaked on May 22 at 00:30 UTC. This event was accompanied by a large CME mainly off the southwest limb. The CME first became visible at 23:50 UTC and does not appear to be geoeffective. The background x-ray flux is at the class B7 level. Coronal holes A recurrent trans equatorial coronal hole was in a geoeffective position on May 21 and could cause a mild geomagnetic disturbance on May 24-25. Forecast The geomagnetic field is expected to be quiet to active on May 22, quiet to unsettled on May 23 and quiet to active on May 24-25. 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 S20W70 0340 HKX 9951 2002.05.12 N12W51 plage 9954 2002.05.15 8 S22W10 0090 DSO 9955 2002.05.15 1 S13W11 0010 HRX 9956 2002.05.16 S08W69 plage 9957 2002.05.16 59 N09E08 0760 EKC beta-gamma 9958 2002.05.17 1 N04W04 0080 HSX 9959 2002.05.17 N10W43 plage 9960 2002.05.18 5 N14E35 0140 DAC beta-delta 9961 2002.05.19 16 S23E48 0330 EAI beta-gamma-delta 9962 2002.05.20 1 N15E47 0020 HSX 9963 2002.05.20 2 N17E60 0210 HAX Total number of sunspots: 95 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) 2002.05 176.0 (1) 133.7 (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]