Solar Terrestrial Activity Report [Image] Last update August 22, 2001 at 04:20 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 active on August 21. Solar wind speed ranged between 387 and 558 km/sec, gradually increasing under the influence of a fairly benign coronal stream originating from a northern hemisphere coronal hole. Solar flare activity was moderate. Solar flux was 160.2, the planetary A index was 14 (3-hour K indices: 2123 3442, Boulder K indices: 2213 3432). Regions 9575 and 9580 were quiet and stable. Region 9582 did not change much and was quiet, some decay was evident by the end of the day. Region 9584 was quiet and stable and could become spotless today. Region 9585 was mostly unchanged. Minor M class flares are possible. Region 9587 was quiet and stable, the region could become spotless today. Region 9588 decayed and was spotless by noon. Region 9589 was spotless early in the day, then reemerged and developed quickly. C class flares are possible. Region 9590 was quiet and stable. New region 9591 rotated partially into view at the southeast limb. There is likely another region (old region 9557) just behind region 9591, and that region is very hot and capable of at least M class flaring. Flares and CMEs A total of 6 C and 1 M class events were observed on August 21. Region 9585 produced a C1.3 flare at 02:00. The region just behind the southeast limb generated an M1.5 impulsive flare at 21:57 UTC. This event was associated with a moderate type II radio sweep. A long duration C2.7 event peaked at 13:03 UTC. Its source was a filament eruption in the southwest quadrant a couple of days rotation from the limb. A partial halo CME was observed in LASCO C3 images in connection with the LDE. There is a possibility that Earth could receive a minor impact from this CME on August 24 or 25. The background x-ray flux is at the class C1 level. Coronal holes A well defined coronal hole in the southern hemisphere will rotate into a geoeffective position on August 23-24. Forecast The geomagnetic field is expected to be quiet to unsettled on August 22-23 and most of August 24. 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 9575 2001.08.11 1 N09W59 0120 HSX 9580 2001.08.14 1 N25W17 0090 HSX 9582 2001.08.15 25 N28W07 0130 DAO 9583 2001.08.16 S23W52 plage 9584 2001.08.16 2 S12W08 0010 AXX 9585 2001.08.16 27 N15E11 0270 DAO 9587 2001.08.17 2 S10E02 0010 BXO 9588 2001.08.19 2 S32W80 0030 BXO now spotless 9589 2001.08.20 7 N14W35 0020 CAO 9590 2001.08.20 1 S28E64 0210 HKX 9591 2001.08.21 1 S18E71 0060 HAX Total number of sunspots: 69 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) 2001.08 151.9 (1) 107.1 (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]