Solar Terrestrial Activity Report [Image] Last update May 28, 2001 at 04:40 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 active on May 27. Solar wind speed ranged between 412 and 667 km/sec. A solar wind shock was observed at SOHO at 14:17 UTC with solar wind speed suddenly increasing from 420 to 550 km/sec. The source of the disturbance is likely what was observed as a partial halo CME following an M1 flare in region 9468 on May 24. Solar flare activity was very low. Solar flux was 146.9, the planetary A index was 9 (3-hour K indices: 1002 3433, Boulder K indices: 1011 2322). Region 9461 was quiet and stable and rotated off the visible disk early on May 28. Region 9462 was quiet and stable. Region 9463 decayed slowly and quietly. There is still a possibility of an M class flare. Region 9465 was quiet and stable, as was region 9467. Region 9468 decayed further and was quiet. Regions 9472 and 9473 both decayed and were spotless by early evening. Region 9474 developed slowly and was quiet. Region 9475 was quiet and stable. New region 9476 emerged near the southwest limb. New region 9477 emerged in the southeast quadrant. New region 9478 emerged in the northeast quadrant. Flares and CMEs No significant flare activity was observed on May 27. The background x-ray flux is at the class B3 level. May 25: A filament eruption in the northwest quadrant began at approximately 02:48 UTC as observed in LASCO EIT images. A slow halo CME was observed in LASCO C3 images during the morning and it is likely that the CME is geoeffective. Coronal holes A large southern hemisphere coronal hole will rotate into a geoeffective position on May 28-30. Forecast The geomagnetic field is expected to be quiet to active on May 28 with a chance of an isolated minor storm interval. A coronal stream will likely arrive on May 31 and cause unsettled to minor storm conditions until June 2. 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 at region numbered sunspots midnight Area Classification Comment 9461 2001.05.15 1 N22W84 0030 HAX 9462 2001.05.17 1 N21W54 0060 HSX 9463 2001.05.18 13 N08W51 0490 EKI beta-gamma 9464 2001.05.19 S09W41 plage 9465 2001.05.20 7 S11W33 0010 BXO 9466 2001.05.21 S04W38 plage 9467 2001.05.21 1 S06W26 0050 HSX 9468 2001.05.21 14 N06W16 0100 DAO 9470 2001.05.22 S16W84 plage 9471 2001.05.23 S13W55 plage 9472 2001.05.23 2 N12E08 0010 AXX 9473 2001.05.26 2 N12E00 0010 AXX 9474 2001.05.26 5 N19E42 0050 DAO 9475 2001.05.26 3 N17E59 0030 CAO 9476 2001.05.27 1 S22W68 0020 HRX 9477 2001.05.27 6 S16E20 0040 DSO 9478 2001.05.27 3 N14E15 0010 BXO Total number of sunspots: 59 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 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) 2001.05 148.6 (1) 118.4 (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]