Solar Terrestrial Activity Report [Image] Last update May 13, 2001 at 04:45 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 1, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update May 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update May 2, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update April 8, 2001)] Recent development The geomagnetic field was quiet to major storm on May 12. Solar wind speed ranged between 579 and 687 km/sec. A strong coronal stream based disturbance started after 10h UTC. The source of the coronal stream is a huge coronal hole in the northern hemisphere. Solar flare activity was moderate. Solar flux was 138.1, the planetary A index was 34 (3-hour K indices: 4246 6434, Boulder K indices: 3235 5434). Regions 9448 and 9451 were quiet and stable. Region 9449 and 9452 both decayed and were spotless by early evening. Region 9454 was mostly quiet and stable but could produce minor M class flares. Region 9455 developed further and could produce further minor M class flares as well as occasional major flares. Magnetograms indicate that the region is magnetically complex and has a delta configuration. New region 9456 emerged on May 11 and was finally numbered as it crossed the central meridian located at a low latitude in the northern hemisphere. Flares and CMEs A total of 5 C and 1 M class events were recorded on May 12. Region 9455 produced a C2.8/1F flare at 10:01, a C4.0 flare at 14:25, a C4.2 flare at 14:48, a C3.5 flare at 17:25 and an M3.0/1B flare at 23:35 UTC. The latter flare was accompanied by a weak type IV sweep and a minor CME where most of the ejected material was observed over the south pole. The CME could be geoeffective but is not likely to cause a strong geomagnetic storm. Region 9454 was the source of a C5.7 flare at 12:10 UTC. Region 9455 generated an M3.6 impulsive flare at 03:04 UTC on May 13. It was associated with a weak type II sweep and possibly a geoeffective CME. The background x-ray flux is at the class B6 level. Coronal holes A large, poorly defined coronal hole in the northern hemisphere was in a geoeffective position on May 9-12. Forecast The geomagnetic field is expected to be unsettled to minor storm on May 13-15 due to a coronal stream. 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 9448 2001.05.01 1 N22W71 0100 HAX 9449 2001.05.02 2 S16W61 0010 AXX now spotless 9451 2001.05.04 4 S21W26 0130 CSO 9452 2001.05.07 2 S10E02 0000 BXO now spotless 9453 2001.05.09 S08W67 plage 9454 2001.05.10 16 N13E46 0410 EAO beta-gamma 9455 2001.05.11 22 S16E03 0190 DAO beta-gamma-delta 9456 2001.05.12 10 N06W04 0060 DAO Total number of sunspots: 57 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.02 174.1 112.9 116.8 (+3.9) 2000.03 208.2 138.5 119.9 (+3.1) 2000.04 184.2 125.5 120.8 (+0.9) cycle 23 sunspot max. 2000.05 184.9 121.6 119.0 (-1.8) 2000.06 179.8 124.9 118.7 (-0.3) 2000.07 202.3 170.1 119.7 (+1.0) 2000.08 163.0 130.5 118.6 (-1.1) 2000.09 182.1 109.7 116.2 (-2.4) 2000.10 167.4 99.4 114.5 (-1.7) 2000.11 178.8 106.8 (112.5 predicted, -2.0) 2000.12 173.6 104.5 (109.9 predicted, -2.6) 2001.01 166.6 95.6 (106.2 predicted, -3.7) 2001.02 146.6 80.1 (101.8 predicted, -4.4) 2001.03 177.7 114.2 (98.2 predicted, -3.6) 2001.04 177.7 108.2 (97.0 predicted, -1.2) 2001.05 151.6 (1) 50.0 (2) (96.3 predicted, -0.7) 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 25-40% 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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ Do you know about the survey which will be held this Summer among the listeners of WWV and WWVH? There is information about this survey at 16 minutes past the hour on WWV and at 47 minutes past the hour on WWVH. If you want to participate send an email with your name and address. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]