Solar Terrestrial Activity Report [Image] Last update October 1, 2000 at 05:20 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update September 2, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update September 2, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update September 2, 2000)] [Historical solar and geomagnetic data charts 1954-2000 (last update August 10, 2000)] Recent development The geomagnetic field was unsettled to major storm on September 30. Solar wind speed ranged between 357 and 464 km/sec. A couple of solar wind shocks were observed during the day, first at ACE at 04:20 UTC, then at 16:08 UTC. After the first shock the interplanetary magnetic field swung moderately to strongly southwards. Only occasional northerly swings were observed for the remainder of the day and the geomagnetic field was at minor to major storm levels from 06h until early on October 1. The source of the shocks may have been the CMEs observed on September 27 and 28, at least in the case of the latter solar wind shock. Solar flare activity was high. Solar flux was 193.6, the planetary A index was 45 (3-hour K indices: 3466 5555, Boulder K indices: 3455 4335). Region 9169 rotated off the visible disk. This region had, for 14 days rotated across the visible solar disk looking like it would produce a major flare at any time. Then, when it was out of view, it produced a major class X flare. Regions 9171 and 9172 were quiet and stable. Region 9173 was stable most of the day, however, the region is decaying early on October 1. Region 9175 decayed into spotless plage. Region 9176 decayed slightly and has M class flaring potential. Region 9177 was quiet and stable. Region 9178 developed slowly and could produce further minor M class flares. New region 9179 emerged in the northeast quadrant near the central meridian and at a high latitude. Flares and CMEs A total of 8 C, 2 M and 1 X class events were recorded on September 30. Region 9173 produced a C2.3 flare at 03:18, a C4.7 flare at 04:34 and a C5.7 flare at 08:59 UTC. Region 9178 generated a C2.2 flare at 08:29, a C3.7 flare at 10:01, a C3.9 flare at 13:06, a long duration M1.0 event peaking at 18:27 (a CME may have been associated with this event, however, with the unavailability of LASCO images after 16:30 UTC this can't be verified), an impulsive M1.8 flare at 20:16 and a C9.9 flare at 20:44 UTC. Region 9169, behind the northwest limb, was the source of a major X1.2 flare at 23:21 UTC. The background x-ray flux is at the class C1 level. Coronal holes A small coronal hole near the equator will rotate into a geoeffective position on September 29 and could cause the geomagnetic field to become unsettled to active on October 2. Forecast The geomagnetic field is expected to be unsettled to minor storm on October 1 and unsettled to active on October 2. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor to useless. 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 9169 20000918 5 N11W92 0230 DKO 9171 20000922 2 S13W38 0020 HSX 9172 20000924 3 N13W07 0040 CSO 9173 20000924 23 S11W02 0260 EAI 9175 20000926 N22E19 plage 9176 20000927 24 S09E31 0310 EKI beta-gamma 9177 20000927 3 N32W33 0020 BXO 9178 20000928 11 S23E38 0120 DAO beta-gamma 9179 20000930 4 N35E07 0010 BXO Total number of sunspots: 75 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.07 165.6 113.5 94.3 (+1.2) 1999.08 170.7 93.7 97.5 (+3.2) 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 (118.7 predicted, +2.1) 2000.04 184.2 125.3 (119.6 predicted, +0.9) 2000.05 184.9 120.8 (120.4 predicted, +0.8) 2000.06 179.8 124.9 (122.0 predicted, +1.6) 2000.07 202.3 169.1 (124.1 predicted, +2.1) 2000.08 163.0 130.6 2000.09 182.1 (1) 158.2 (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]