Solar Terrestrial Activity Report [Image] Last update May 21, 2001 at 04:15 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 unsettled on May 20. Solar wind speed ranged between 347 and 441 km/sec. Solar flare activity was high. Solar flux was 141.5, the planetary A index was 10 (3-hour K indices: 2332 3322, Boulder K indices: 1321 3222). Region 9454 was spotless all day in all available images. Region 9461 decayed slightly and was quiet. Region 9462 was quiet and stable. Region 9463 developed slowly and could produce minor M class flares. Region 9464 was quiet and stable. New region 9465 rotated into view at the southeast limb. Flares and CMEs A total of 9 C and 2 M class events were recorded on May 20. None of the flares were optically correlated, however, LASCO images indicate that several flares had their origin in region 9455 behind the southwest limb. A major M6.4 flare was recorded at 06:03 UTC and had an associated weak type II sweep. An unimpressive, fairly small CME was observed off the southwest limb. The flare was a proton flare as well with the above 10 MeV proton flux nearly reaching event level. An M1.5 flare occurred at 09:20 and, with the same origin, a C6.1 flare at 11:40 and a C2.9 flare at 14:41 UTC. An interesting C9.0 flare was noted at 03:20 UTC on May 21. Its source appears to have been in or near region 9461. If a CME was generated by this event it will likely be geoeffective. The background x-ray flux is at the class B4 level. Coronal holes An extension of a large southern hemisphere coronal hole was in a geoeffective position on May 20-21. Forecast The geomagnetic field is expected to be quiet to unsettled on May 21-22. A coronal stream will likely arrive on May 23 and cause unsettled to active conditions with a chance of isolated minor storm intervals. 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 no. Location region numbered sunspots at AreaClassification Comment midnight 9454 2001.05.10 4 N15W60 0030 AXX actually spotless! 9457 2001.05.13 S21W85 plage 9459 2001.05.14 N27W86 plage 9460 2001.05.14 S24W17 plage 9461 2001.05.15 12 N22E10 0130 DSO 9462 2001.05.17 1 N20E36 0060 HAX 9463 2001.05.18 14 N09E46 0400 EKO beta-gamma? 9464 2001.05.19 4 S07E53 0070 DAO 9465 2001.05.20 4 S08E63 0110 DAO Total number of sunspots: 39 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) 2001.05 147.2 (1) 81.5 (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]