Solar Terrestrial Activity Report [Image] Last update May 23, 2002 at 03:55 UTC. Last minor update posted at 13:28 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 22. Solar wind speed ranged between 370 and 432 km/sec. Early on May 23 it appears as if a coronal stream could be arriving at any time. Solar flare activity was low. Solar flux was 181.1, the planetary A index was 14 (3-hour K indices: 2234 3333, Boulder K indices: 2123 3321). Region 9948 was mostly unchanged and quiet, the region is rotating over the southwest limb. Region 9954 decayed further and was quiet. Region 9955 decayed and was spotless by the end of the day. Region 9957 decayed fairly quickly and lost penumbral area and spots both south and north of the central spots. There may be a weak delta structure in the central spots area, but otherwise the opposite polarities are well defined with very little intermixing. The region could produce minor M class flares. Region 9958 was quiet and stable. Region 9960 was mostly unchanged and remains a compact region with a magnetic delta structure. A minor M class flare is possible. Region 9961 developed slowly and added penumbral area both in the leading and intermediate spots section. The region does not currently have a magnetic delta structure, however, further growth could quickly reestablish the region as a significant flare producer. Region 9962 was quiet and stable. Region 9963 developed slowly and could produce minor M class flares. New regions 9964 (in the southeast quadrant near the central meridian) and 9965 (near the southeast limb) were finally numbered by SEC/NOAA. The above 10 MeV proton flux became enhanced after 06h UTC. A proton event began later in the day and has so far peaked above 100 pfu early on May 23. The source of this event is likely the filament/prominence eruption discussed below. Comment added at 10:23 UTC on May 23: A very strong solar wind shock was observed at SOHO at 10:17 UTC. Solar wind speed has jumped to near 600 km/sec and the interplanetary magnetic field has swung strongly southwards. The source of this shock is likely the early arrival of the full halo CME observed just over 30 hours ago. A major disturbance is likely to begin when the CME impacts the Earth in about 30 minutes time. Further updates will be posted today, the next one probably within a couple of hours. Comment added at 12:03 UTC: The interplanetary magnetic field has at times been very strongly to extremely strongly southwards since the shock and is currently causing a severe geomagnetic storm. Solar wind speed is near 800 km/sec. The above 10 MeV proton event has peaked near 800 pfu. Comment added at 13:28 UTC: Solar wind speed appears to have peaked just above 1000 km/sec. Since 12:15 UTC the interplanetary magnetic field has been mostly northwards and this will cause a decrease in the geomagnetic disturbance levels. The planetary A index for the 12-13h interval was 111 (Kp7) which is severe storm level. Flares and CMEs A total of 4 C class events were recorded on May 22. Region 9961 produced a C2.5 flare at 15:47 and a C2.4 flare at 20:54 UTC. A huge and amazing filament eruption was associated with a long duration C5.0 event peaking at 03:54 UTC. The location of the filament was in the southwest quadrant and the eruption caused a large, wide and fast full halo CME. The effects of the eruption were easily observed even in the southeast quadrant of the solar disk where several other filaments suddenly displayed quick motions. This CME will impact the Earth and could cause a major disturbance (active to severe storm). The impact time is uncertain but will likely occur between 12h today and 03h on May 24. The initial shock could be complex due to the coronal stream ahead of the CME. The background x-ray flux is at the class B5 level. Coronal holes A recurrent trans equatorial coronal hole was in a geoeffective position on May 20-21 and could cause a mild geomagnetic disturbance on May 23-24. Forecast The geomagnetic field is expected to be quiet to minor storm until the arrival of the CME associated with a large filament/prominence eruption early on May 22. The CME will likely arrive either sometime between noon on May 23 and very early on May 24 and could cause a major geomagnetic storm with the disturbance ranging from active to severe or very severe storm levels. 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 Location region numbered no. at Area Classification Comment sunspots midnight 9948 2002.05.10 1 S21W84 0300 HHX 9951 2002.05.12 N12W64 plage 9954 2002.05.15 8 S22W26 0060 DSO too many spots 9955 2002.05.15 2 S13W24 0010 CRO now spotless 9956 2002.05.16 S08W82 plage 9957 2002.05.16 47 N10W04 0520 EAI beta-gamma-delta 9958 2002.05.17 1 N04W04 0070 HSX 9959 2002.05.17 N10W56 plage 9960 2002.05.18 6 N14E19 0120 DAC beta-delta 9961 2002.05.19 21 S22E34 0330 EAI beta-gamma 9962 2002.05.20 1 N15E34 0030 HSX 9963 2002.05.20 12 N16E48 0340 DHO 9964 2002.05.22 4 S15E08 0010 BXO 9965 2002.05.22 4 S10E62 0080 CAO Total number of sunspots: 107 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) 2002.05 176.2 (1) 140.7 (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]