Solar Terrestrial Activity Report [Image] Last update February 25, 2001 at 01:20 UT. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update February 2, 2001) - Did cycle 23 peak in April 2000?] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2001)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 2001)] [Historical solar and geomagnetic data charts 1954-2000 (last update January 18, 2001)] Recent development The geomagnetic field was quiet to unsettled on February 24. Solar wind speed ranged between 315 and 377 km/sec. Solar flare activity was low. Solar flux was 137.3 (average solar flux for the current month will become the lowest since September 1999), the planetary A index was 6 (3-hour K indices: 1202 2310, Boulder K indices: 2202 2311). Region 9354 decayed slowly and was quiet, the region will rotate over the west limb on February 26. Region 9357 was quiet and stable, the region decayed during the latter half of the day and could become spotless today. Region 9358 was spotless all day in all available images, yet, SEC/NOAA managed to observe 1 spot. Region 9359 decayed, particularly during the latter half of the day, and was quiet. Region 9360 was quiet and stable. Region 9361 was spotless all day, still SEC/NOAA observed one spot. Flares and CMEs Only 1 C class event was observed on February 24, it was an optically uncorrelated C1.1 flare at 13:57 UT. February 23: A long duration C2.2 event peaked at 23:19 UT, its source was in the southeast quadrant, just east of region 9360. A coronal mass ejection was produced and could be observed in LASCO images before midnight. The CME appears to have been a faint full halo CME. The background x-ray flux is at the class B2-B3 level. Coronal holes A small, well placed coronal hole in the northern hemisphere was in a geoeffective position on February 23. A coronal hole in the southern hemisphere may have been located too far to the south to have been geoeffective when it rotated across the central meridian on Feb.23-24. Forecast The geomagnetic field is expected to be quiet on February 25. There is a chance of unsettled to active conditions on February 26 due to a coronal stream. Sometime between late on February 26 and late on February 27 a CME will likely impact the magnetosphere and cause unsettled to active conditions. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to 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 region numbered sunspots at AreaClassification Comment midnight 9352 2001.02.15 S21W48 9354 2001.02.16 15 S09W72 0280 DAO 9355 2001.02.18 N20W44 plage 9357 2001.02.18 5 S25W46 0020 CRO 9358 2001.02.18 1 S07W34 0010 HSX actually spotless! 9359 2001.02.20 16 N13E23 0240 EAO 9360 2001.02.21 1 S10E17 0020 HRX 9361 2001.02.22 1 S16W18 0010 AXX actually spotless! Total number of sunspots: 39 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.11 191.5 133.2 111.0 (+3.2) 1999.12 169.8 84.6 111.1 (+0.1) 2000.01 158.1 90.1 112.9 (+1.8) 2000.02 174.1 112.9 116.8 (+3.9) 2000.03 208.2 138.5 119.9 (+3.1) 120.8 (+0.9) 2000.04 184.2 125.5 cycle 23 peak candidate 2000.05 184.9 121.6 119.0 (-1.8) 2000.06 179.8 124.9 118.7 (-0.3) 2000.07 202.3 170.1 119.8 (+1.1) 2000.08 163.0 130.5 (119.5 predicted, -0.3) 2000.09 182.1 109.7 (117.9 predicted, -1.6) 2000.10 167.4 100.1 (116.3 predicted, -1.6) 2000.11 178.8 106.5 (114.4 predicted, -1.9) 2000.12 173.6 104.5 (111.8 predicted, -2.6) 2001.01 166.6 95.7 (108.2 predicted, -3.6) 2001.02 148.9 (1) 117.4 (2) 1) Running average based on the daily 20:00 UT 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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]