Solar Terrestrial Activity Report [Image] Last update May 10, 2001 at 04:55 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 active to minor storm on May 9. Solar wind speed ranged between 406 and 573 km/sec. The source of the disturbance is uncertain, and there may even have been two separate disturbances with the second one beginning at approximately 11h UTC. Solar flare activity was low. Solar flux was 129.4, the planetary A index was 32 (3-hour K indices: 5544 4444, Boulder K indices: 5543 4334). Region 9445 decayed further and was spotless by the end of the day. Regions 9448, 9449, 9451 and 9452 were quiet and stable. Region 9450 was spotless all day in all available images. New region 9453 emerged in the southwest quadrant early in the day but was decaying late in the day. Flares and CMEs A total of 2 C class events were recorded on May 9. Region 9445 produced a C1.1 flare at 06:03 and a C1.5 flare at 08:53 UTC. A long duration event was observed early on May 10 with its origin near the northwest limb. The background x-ray flux is at the class B4 level. Coronal holes A large, poorly defined coronal hole in the northern hemisphere could rotate into a geoeffective position on May 9-12. Forecast The geomagnetic field is expected to be quiet to minor storm on May 10 and quiet to unsettled on May 11. 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 no. Location at region numbered sunspots midnight Area Classification Comment 9444 2001.04.28 S11W81 plage 9445 2001.04.28 7 N25W67 0080 EAO 9448 2001.05.01 3 N21W30 0110 CSO 9449 2001.05.02 5 S16W21 0060 CAO 9450 2001.05.04 1 S01W78 0010 AXX actually spotless 9451 2001.05.04 6 S21E13 0140 CAO 9452 2001.05.07 1 S09E41 0020 AXX 9453 2001.05.09 5 S08W28 0020 CSO Total number of sunspots: 28 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) 2001.05 157.1 (1) 39.8 (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]