Solar Terrestrial Activity Report [Image] Last update February 13, 2001 at 01:30 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) - Cycle 23 peaked 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 on February 12. Solar wind speed ranged between 387 and 469 km/sec. A weak solar wind shock was observed at ACE at 20:43 UT. Solar wind speed increased from 420 to 460 km/sec and the interplanetary magnetic field strengthened. The source of the disturbance may have been the halo CME observed early on February 10. Solar flare activity was low. Solar flux was 144.6, the planetary A index was 4 (3-hour K indices: 1000 1222, Boulder K indices: 2101 2323). Region 9334 decayed and was mostly quiet, the region was spotless at the end of the day. Region 9335 was quiet and is currently spotless. Region 9338 decayed further, occasional C class flares are possible. Region 9339 decayed slowly and was quiet. Region 9345 decayed into spotless plage. Region 9347 was quiet and stable, as were regions 9349 and 9350. Region 9348 decayed and was spotless by the end of the day. Flares and CMEs A total of 2 C class events were recorded on February 11. Region 9338 generated a C5.9 flare at 01:18 UT. Region 9334 produced a C4.2 flare at 20:37 UT, it was accompanied by a moderate type II sweep and likely a fast CME. February 11: A C6.5 long duration event peaked at 01:23 UT. Its source was near the northwest limb but not inside any of the numbered regions. A full halo CME was observed soon after the flare and could influence the geomagnetic field on February 13 and 14. The flare caused a minor enhancement in the above 10 MeV proton flux most of the day. The background x-ray flux is at the class B3 level. Coronal holes A poorly defined coronal hole in the northern hemisphere could rotate into a geoeffective position on February 12-13. Forecast The geomagnetic field is expected to be quiet to active on February 12-13 with a chance of minor storm intervals. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair. 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 9334 2001.02.01 2 N13W65 0030 CRO 9335 2001.02.03 1 N11W55 0010 HRX 9337 2001.02.03 S28W40 plage 9338 2001.02.04 11 S20W41 0170 CSO 9339 2001.02.04 4 S09W33 0100 CSO 9340 2001.02.05 S11W88 plage 9341 2001.02.06 S09W56 plage 9342 2001.02.06 S26W23 plage 9343 2001.02.07 N03W57 plage 9344 2001.02.08 N30W40 plage 9345 2001.02.08 S20W33 plage 9347 2001.02.09 3 N04E25 0050 DSO 9348 2001.02.10 3 N13W20 0020 CAO 9349 2001.02.10 1 N28E34 0030 HSX 9350 2001.02.11 1 N18E56 0060 HAX Total number of sunspots: 26 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 (119.7 predicted, -0.1) 2000.09 182.1 109.7 (118.4 predicted, -1.3) 2000.10 167.4 100.1 (116.7 predicted, -1.7) 2000.11 178.8 106.5 (114.8 predicted, -1.9) 2000.12 173.6 104.5 (112.2 predicted, -2.6) 2001.01 166.6 95.7 (108.7 predicted, -3.5) 2001.02 159.5 (1) 65.6 (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 noted in solar links. Comments and suggestions are always welcome. ------------------------------------------------------------------------ [DX-Listeners' Club] [DX News] [StudyWeb]