Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update February 12, 2000 at 03:10 UTC. Minor update posted at 05:37 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update February 3, 2000)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update February 3, 2000)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 3, 2000)] [Historical solar and geomagnetic data charts 1954-1999] [Experimental solar data chart January 1998-September 1999] Recent development The geomagnetic field was quiet to active on February 11. Solar wind speed ranged between 396 and 620 km/sec. A solar wind shock was observed at 02:14 UTC at ACE. Solar wind speed increased abruptly from 420 to 550 km/sec. This was likely the arrival of the CME observed on February 8. The interplanetary magnetic field was mostly northwards following the shock. A more significant solar wind shock was observed at 23:16 UTC at ACE. An abrupt increase in solar wind speed from 430 to 620 km/sec was observed. The IMF has at times been strongly southwards since the shock and this has caused the geomagnetic field to reach minor storm levels. The second shock was likely caused by the CME observed on February 9. Solar flare activity was low. Solar flux was 170.2, the planetary A index was 13 (3-hour Kp indices: 3423 3333, Boulder K indices: 3423 3233). Region 8854 decayed into spotless plage. Region 8855 was quiet and stable. Region 8856 produced a single C flare and a CME. Region 8858 decayed further and is unlikely to produce other than occasional C class flares. Region 8861 rotated off the visible disk. Region 8862 was quiet and stable, as were regions 8863 and 8864. Region 8867 developed slowly and was quiet. Region 8868 was mostly unchanged and could produce C flares. Regions 8869 and 8870 were quiet and stable. New region 8871 emerged in the southwest quadrant near the central meridian. New region 8872 rotated partly into view at the southeast limb. Comment added at 05:37 UTC on February 12: Region 8858 produced a long duration M1.7 event peaking at 04:10 UTC. A possibly geoeffective CME may have been associated with the event. An M flare from a region with the small sunspot areal coverage of region 8858 is unusual. Recent ACE solar wind data hints at the possibility of severe storming later on today. The geomagnetic field is currently at minor to major storm levels. Flares and CMEs 2 C flares were recorded on February 11. Region 8858 produced a C1.8 flare at 14:59 UTC. Region 8856 was the source of a C2.3 flare at 12:34 UTC and an associated partial halo coronal mass ejection. This CME could impact Earth on February 14 or 15 and cause a few unsettled to active intervals. A much more impressive CME was observed at the northwest limb starting at 23:06 UTC in LASCO C2 images. February 10: Region 8858 was the source of an interesting C7.3/1N long duration event peaking at 02:08 UTC. A moderately strong type II sweep with an estimated shock speed of 1000 km/sec associated with a full halo coronal mass ejection was observed as well. This event occurred very near the central meridian and the CME will impact Earth, probably on February 12. February 9: A large filament eruption in spotless region 8853 was the most impressive event of the day, a C7.4/2F long duration event peaking at 20:06 UTC. This resulted in a wide and full halo coronal mass ejection which is likely to impact Earth on February 12 or 13 (unless it is overtaken by the faster CME mentioned above, the result could be a complex solar wind pattern). The background x-ray flux is at the class B7 level. Coronal holes An emerging trans equatorial coronal hole was in a geoeffective position on February 10. The resulting coronal stream is not likely to be observed at Earth due to the effects from the above mentioned CMEs. A coronal hole in the northern hemisphere will rotate into a possibly geoeffective position on February 13 and could cause unsettled to active intervals on Feb.16-17. Forecast The geomagnetic field is expected to be active to major storm on February 12 and unsettled to major storm on Feb.13. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally 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 8853 20000201 S13W66 plage 8854 20000201 S34W44 plage 8855 20000202 2 N18W74 0010 AXX 8856 20000202 4 S14W34 0060 EAO 8858 20000203 10 N24W25 0040 CAO 8860 20000204 N30W85 plage 8861 20000205 2 N08W95 0240 EAO 8862 20000206 2 S06E08 0150 HSX 8863 20000208 2 S16E30 0000 AXX 8864 20000208 1 N43W54 0000 AXX 8865 20000208 S12W17 plage 8866 20000208 N15E25 plage 8867 20000209 7 S16E08 0020 BXO 8868 20000209 13 S24E07 0060 DSO 8869 20000210 5 S26E61 0070 CAO 8870 20000210 1 N18E64 0060 HAX 8871 20000211 3 S14W09 0010 AXX 8872 20000211 2 S28E79 0070 HSX Total number of sunspots: 54 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 1999.01 140.6 62.0 82.6 (+4.7) 1999.02 141.9 66.3 84.6 (+2.0) 1999.03 126.3 68.8 83.8 (-0.8) 1999.04 117.2 63.7 85.4 (+1.6) 1999.05 148.4 106.4 90.4 (+5.0) 1999.06 169.8 137.7 93.0 (+2.6) 1999.07 165.6 113.5 94.4 (+1.4) 1999.08 170.7 93.7 (97.4 predicted, +3.0) 1999.09 135.7 70.9 (102.4 predicted, +5.0) 1999.10 164.8 116.4 (107.5 predicted, +5.1) 1999.11 191.5 132.7 1999.12 169.8 86.4 2000.01 158.1 90.2 2000.02 168.2 (1) 60.6 (2) 1) Running average based on the daily 20:00 UTC solar flux measurement at 2800 MHz by DRAO. 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]