Solar Terrestrial Activity Report [Image] Last update August 21, 2001 at 02:30 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update August 1, 2001)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update August 1, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update August 1, 2001)] [Historical solar and geomagnetic data charts 1954-2001 (last update July 27, 2001)] Recent development The geomagnetic field was quiet to unsettled on August 20. Solar wind speed ranged between 356 and 445 km/sec. Solar flare activity was low. Solar flux was 156.1, the planetary A index was 11 (3-hour K indices: 2113 3332, Boulder K indices: 1113 3322). Region 9573 was quiet and rotated out of view late in the day. Regions 9575 and 9580 were quiet and stable. Region 9581 decayed and was spotless by early evening. Region 9582 developed slowly and will likely produce further C class flares. A minor M class flare is possible. Region 9584 was quiet and stable. Region 9585 was mostly unchanged. Minor M class flares are possible. Region 9587 was quiet and stable. Region 9588 decayed slowly and was quiet. New region 9589 emerged briefly in the northwest quadrant, no spots were observed by early evening. New region 9590 rotated partly into view at the southeast limb. A hot and interesting region is approaching the southeast limb at approximately latitude S17. This is possibly the return of old region 9557, the likely source of a large backside proton event a week ago. Flares and CMEs A total of 4 C class events were observed on August 20. Region 9585 produced a C1.2 flare at 03:02 UTC. Region 9582 generated a C2.0 flare at 05:25 and a C3.6/1F flare at 08:22 UTC. A long duration C2.3 event peaked at 19:37 UTC. LASCO EIT images suggest that its source was in the region approaching the southeast limb. A weak type II radio sweep was recorded as well and a weak full halo CME was first observed in LASCO C3 images at 21:42 UTC. Another weak full halo CME from a backside source, this time behind the west limb, was observed in C3 beginning at 09:42 UTC. The background x-ray flux is at the class C1 level. Coronal holes A coronal hole in the southern hemisphere could rotate into a geoeffective position on August 24. Forecast The geomagnetic field is expected to be quiet to unsettled on August 21. 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 9573 2001.08.08 1 S08W87 0030 HAX 9575 2001.08.11 1 N10W46 0110 HSX 9579 2001.08.14 S24W89 plage 9580 2001.08.14 1 N25W05 0100 HSX 9581 2001.08.15 3 S26W77 0010 BXO 9582 2001.08.15 22 N28E05 0130 DSO beta-gamma 9583 2001.08.16 S23W39 plage 9584 2001.08.16 2 S12E05 0010 HSX 9585 2001.08.16 22 N15E22 0250 DAO beta-gamma 9586 2001.08.17 S16W88 plage 9587 2001.08.17 1 S11E15 0010 HRX 9588 2001.08.19 4 S32W70 0090 DAO 9589 2001.08.20 4 N15W21 0010 BXO 9590 2001.08.20 1 S28E80 0150 HSX Total number of sunspots: 62 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.03 208.2 138.5 119.9 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.7 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 95.6 108.8 (-3.3) 2001.02 146.6 80.6 (103.3 predicted, -5.5) 2001.03 177.7 113.5 (99.7 predicted, -3.6) 2001.04 177.7 108.2 (98.5 predicted, -1.2) 2001.05 147.1 97.3 (97.9 predicted, -0.6) 2001.06 173.0 134.0 (95.1 predicted, -2.8) 2001.07 131.3 82.2 (93.2 predicted, -1.9) 2001.08 151.5 (1) 101.6 (2) (93.8 predicted, +0.6) 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]