Solar Terrestrial Activity Report [Image] Last update October 5, 2000 at 04:55 UTC. Minor update posted at 12:44 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update October 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update October 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update October 2, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update August 10, 2000)] Recent development The geomagnetic field was quiet to major storm on October 4. Solar wind speed ranged between 342 and 447 km/sec. A minor solar wind shock was observed at 13:30 UTC and contributed to keep the level of the current disturbance at the minor to major storm level. A strong solar wind shock was observed at ACE at 02:35 UTC on October 5 with solar wind speed increasing abruptly from 360 to 470 km/sec. The total field of the interplanetary magnetic field increased significantly as well, and should the IMF swing fully southwards major to severe storming will be possible. Solar flare activity was low. Solar flux was 184.1, the planetary A index was 45 (3-hour K indices: 1455 6555, Boulder K indices: 2355 5544). Region 9172 was quiet and stable. Region 9173 did not change significantly and could produce minor M class flares. Region 9176 decayed slowly and may be capable of producing a minor M class flare. Region 9177 decayed slowly and could produce C flares, the region is rotating off the visible disk. Region 9178 was mostly unchanged and could produce minor M class flares. Region 9179 was quiet and stable. Region 9180 decayed into spotless plage. Region 9181 was mostly quiet, C class flares are possible. Region 9182 developed slowly and could generate C flares and perhaps a minor M class flare. Regions 9183 and 9184 were quiet and stable. New region 9185 emerged in the southwest quadrant. New region 9186 emerged quickly in the northwest quadrant. Comment added at 12:44 UTC on October 5: The geomagnetic field was at minor to severe storm levels for the first half of the day. The planetary A index for the 03-06h interval was 103, then increased to 155 during the 06-09h period and was 146 from 09 to 12h UTC. The most intense storming was observed 11-12h UTC with some sites reporting very severe to extremely severe storming. The interplanetary magnetic field was very strongly southwards at ACE 05:15 to 05:45 and 10:00 to 11:30 UTC. This major geomagnetic storm should decrease in intensity towards the end of the day. Flares and CMEs A total of 4 C class events were recorded on October 4. Region 9178 produced a C2.1 flare 00:31 and a C1.2 flare at 17:37 UTC. Region 9181 generated a C2.6 flare at 05:26 and a C3.4 flare at 15:14 UTC. The background x-ray flux is at the class B7 level. Coronal holes A small coronal hole in the northern hemisphere could rotate into a geoeffective position on October 7. Forecast The geomagnetic field is expected to be active to major storm on October 5 and quiet to active on October 6. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 9172 20000924 1 N13W62 0030 HSX 9173 20000924 20 S12W53 0300 EAI beta-gamma 9175 20000926 N22W33 plage 9176 20000927 15 S09W22 0190 CSO 9177 20000927 2 N28W80 0100 CAO 9178 20000928 21 S22W16 0250 EAI beta-gamma 9179 20000930 2 N36W42 0010 BXO 9180 20001001 S32W63 plage 9181 20001002 11 S27E41 0130 DAI 9182 20001002 8 N01E51 0160 EAO 9183 20001003 2 S32W43 0010 HSX 9184 20001003 3 S13E53 0020 CSO 9185 20001004 1 S18W49 0000 AXX 9186 20001004 9 N14W41 0040 DAO Total number of sunspots: 95 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.09 135.7 71.5 102.3 (+4.8) 1999.10 164.8 116.7 107.8 (+5.5) 1999.11 191.5 133.2 110.9 (+3.1) 1999.12 169.8 84.6 111.0 (+0.1) 2000.01 158.1 90.1 112.8 (+1.8) 2000.02 174.1 112.9 116.6 (+3.8) 2000.03 208.2 138.5 119.8 (+3.2) 2000.04 184.2 125.3 (121.7 predicted, +1.9) 2000.05 184.9 120.8 (122.5 predicted, +0.8) 2000.06 179.8 124.9 (124.1 predicted, +1.6) 2000.07 202.3 169.1 (126.2 predicted, +2.1) 2000.08 163.0 130.6 (124.8 predicted, -1.4) 2000.09 182.1 109.9 2000.10 195.1 (1) 24.5 (2) 1) Running average based on the daily 20:00 UTC solar flux value at 2800 MHz. 2) Unofficial, accumulated value. The official value 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 in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]