Solar Terrestrial Activity Report [Image] Last update October 4, 2002 at 03:50 UTC. Minor update posted at 08:27 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, 2002)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update October, 2002)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update October 2, 2002)] [Historical solar and geomagnetic data charts 1954-2002 (last update August 16, 2002)] Recent activity The geomagnetic field was unsettled to major storm on October 3. Solar wind speed ranged between 406 and 522 km/sec. gradually decreasing all day. The interplanetary magnetic field has been almost fully southwards since approximately 11h UTC on Oct.3 and this has caused active to major geomagnetic storm conditions. The current disturbance should subside after noon today. Solar flare activity was moderate. Solar flux was 145.9, the planetary A index was 33 (S.T.A.R. calculated average value based on three hour Ap indices: 33.6). Three hour interval K indices: 63434555 (planetary), 63333444 (Boulder). The background x-ray flux is at the class B9 level. Region 10129 reemerged early in the day with several spots as the plage in the area brightened considerably. The region rotated over the northwest limb late in the day. Region 10134 decayed quietly and is rapidly losing its trailing spots. Occasional low level C class flares are possible. Flare: C2.5 at 12:44 UTC. Region 10137 decayed losing quite a bit of its penumbral area. There is still a negative polarity area within the trailing positive polarity. This area had nearly disappeared by noon but strengthened later on and could cause further minor M class flares. Flare: M2.1/1N at 02:21 UTC. Region 10138 decayed slowly and could become spotless tomorrow. Region 10139 developed quickly during the second half of the day and has a magnetic delta structure within the leading penumbra. M class flares are possible. The small regions which emerged in the southeast quadrant on October 2 decayed and became spotless. Region 10137 produced an M1.0 flare at 00:44 UTC on October 4. Comment added at 08:27 UTC on October 4: Region 10137 was the source of an M4.0/1N flare at 05:37 UTC. I have been waiting for LASCO images (covering the hours after the eruption) to become available to determine if there was a CME associated with the flare. As there are no images yet, another update will be posted later on if there was a geoeffective CME. The geomagnetic field has so far today been at minor to severe storm levels. ACE data indicates that the IMF is not anymore fully southwards. This should cause a decrease in the disturbance levels, first to active near noon, then to quiet to unsettled towards the evening. Coronal mass ejections (CMEs) October 3: A full halo CME was observed in LASCO C2 images beginning at 03:54 at high latitudes off the southeast limb. This CME was not associated with the earlier M2 flare in region 10137 and seems to have had an origin 5-6 days behind the southeast limb. Another CME was observed over the northwest limb beginning at 05:54 UTC and was associated with activity in region 10129. Coronal holes A coronal hole in the southern hemisphere will rotate into a geoeffective position on October 4-6. Forecast The geomagnetic field is expected to be quiet to severe storm on October 4 and quiet to unsettled on October 5-6. A coronal stream is expected to arrive on October 7 and could cause unsettled to active conditions that day and the next couple of days. 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 Location region numbered no. at Area Classification Comment sunspots midnight several spots were 10129 2002.09.22 N28W92 observed before the region rotated out of view 10134 2002.09.24 14 N14W42 0230 DAI area below 0200 at midnight 10135 2002.09.27 S23W75 plage 10136 2002.09.29 S31W87 plage beta-gamma 10137 2002.09.29 19 S19W05 0310 EKI area near 0200 at midnight, classification DAI then with 10 spots observed 10138 2002.10.01 3 N10W37 0020 HSX beta-gamma-delta 10139 2002.10.02 5 N14E59 0160 CSO area near 0200 at midnight 11 spots observed then, classification DAI Total number of sunspots: 41 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 2000.04 184.2 125.5 120.8 cycle 23 sunspot max. 2000.07 202.3 170.1 119.8 2001.09 233.2 150.7 114.1 (+0.5) 2001.10 207.6 125.5 114.0 (-0.1) 2001.11 210.6 106.5 115.5 (+1.5) 2001.12 235.1 132.2 114.6 (-0.9) 2002.01 226.6 114.1 113.5 (-1.1) 2002.02 205.0 107.4 114.7 (+1.2) 2002.03 179.5 98.4 113.4 (-1.3) 2002.04 189.8 120.4 (109.7 predicted, -3.7) 2002.05 178.4 120.8 (105.9 predicted, -3.8) 2002.06 148.7 88.5 (101.4 predicted, -4.5) 2002.07 173.5 99.9 (96.5 predicted, -4.9) 2002.08 183.6 116.4 (92.5 predicted, -4.0) 2002.09 175.8 109.3 (88.7 predicted, -3.8) 2002.10 140.5 (1) 9.2 (2) (84.6 predicted, -4.1) 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 25-45% 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. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News]