Solar Terrestrial Activity Report [Image] Last update July 31, 2001 at 04:10 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update July 2, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update July 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update July 2, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update July 27, 2001)] Recent development The geomagnetic field was quiet to active on July 30. Solar wind speed ranged between 301 and 332 km/sec. A coronal stream began to influence the field at approximately 21h UTC and solar wind speed has been increasing slowly since then. Solar wind density peaked early on July 31 at an unusually high level. Solar flare activity was low. Solar flux was 114.5 (again the lowest solar flux at 20h UTC since September 9, 1999, when 106.5 was measured), the planetary A index was 9 (3-hour K indices: 2122 2334, Boulder K indices: 2121 1234). Region 9557 developed slowly early on, then began to decay slowly. Region 9559 decayed fairly quickly and could become spotless today. New region 9561 rotated into view at the southeast limb. New region 9562 rotated into view at the northeast limb and appears to be capable of producing at least C class flares. Flares and CMEs A total of 2 C class events were recorded on July 30. Region 9562 produced a C4.5 flare at 08:34 UTC. A C6.0 flare occurred at 20:43 UTC and was associated with a weak type II radio sweep. The flare was optically uncorrelated. July 28: A filament located in the northwest quadrant of the solar disk and fairly near the center of the disk disappeared during the day. Because of problems with the SOHO spacecraft it is difficult to tell whether or not a geoeffective CME was produced. If there was a CME it could reach Earth on August 1. The background x-ray flux is at the class B2-B3 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be unsettled to active on July 31 due to a coronal stream, isolated minor storm intervals are possible. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to 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 Area Classification Comment midnight 9552 2001.07.23 N13W76 plage 9553 2001.07.23 N14W59 plage 9555 2001.07.24 S09W25 plage 9557 2001.07.26 14 S19E22 0110 EAO 9558 2001.07.26 N18W82 plage 9559 2001.07.27 3 S24W23 0010 CRO 9560 2001.07.29 N18E33 plage 9561 2001.07.30 5 S13E63 0070 DAO 9562 2001.07.30 2 N05E70 0140 DAO beta-gamma? Total number of sunspots: 24 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) 2000.11 178.8 106.8 112.8 (-1.7) 2000.12 173.6 104.4 112.1 (-0.7) 2001.01 166.6 95.6 (109.6 predicted, -2.5) 2001.02 146.6 80.6 (104.8 predicted, -4.8) 2001.03 177.7 113.5 (101.2 predicted, -3.6) 2001.04 177.7 108.2 (100.0 predicted, -1.2) 2001.05 147.1 97.3 (99.3 predicted, -0.7) 2001.06 173.0 134.0 (96.6 predicted, -2.7) 2001.07 131.8 (1) 121.8 (2) (94.7 predicted, -1.9) 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]