Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 14, 1999 at 02:20 UTC. [Solar and geomagnetic data - last 4 weeks (updated daily)] [Solar wind and electron fluence charts (updated daily)] [Solar cycles 21-23 (last update December 2, 1999)] [Solar cycles 1-20] [Graphical comparison of cycles 21, 22 and 23 (last update December 2, 1999)] [Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update December 2, 1999)] [Historical solar and geomagnetic data charts 1954-1999] [Experimental solar data chart January 1998-September 1999] Recent development The geomagnetic field was quiet to minor storm on December 13. A few observatories registered isolated major storm intervals 06-15h UTC. Solar wind speed ranged between 395 and 607 km/sec. The interplanetary magnetic field was moderately to strongly southwards until 14:15 UTC when the field swung suddenly (and very strongly) northwards. The IMF was mostly northwards for the remainder of the day although at times in a fairly complicated pattern. Solar flare activity was low. Solar flux was 166.1, the planetary A index was 26 (3-hour Kp indices: 3455 5421, Boulder K indices: 3446 4421). Region 8785 was quiet and stable, the region will rotate off the visible disk early today. Region 8788 decayed slowly and was quiet, the region will rotate off the visible disk late on Dec.15. Region 8790 decayed further and was quiet. Region 8792 decayed slowly and was quiet. Region 8793 was quiet and could become spotless within a couple of days. Regions 8794 and 8795 were quiet and stable. New regions 8796 and 8797 emerged in the southeast quadrant near the central meridian while new regions 8798 and 8799 rotated partly into view at the southeast limb. Flares and CMEs 2 C flares were recorded on December 13, none of them were optically correlated to any of the active regions currently visible. Near realtime LASCO images are again available online. A full halo CME was observed beginning at 08:54 UTC on December 12. The source of this event is unknown and could have a backside origin. If the CME had its source on the visible disk the CME would likely impact Earth on Dec.15. A partial halo CME was observed covering most of the southern hemisphere at 18:30 on December 13. This may have been related to a filament eruption in the southeast quadrant. The background x-ray flux is at the class B7 level. Coronal holes A trans equatorial coronal hole was in a geoeffective position on December 10-11. Forecast The geomagnetic field is expected to be quiet to active on December 14. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally poor to 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 8785 991201 1 N16W87 0030 HAX 8788 991202 7 N15W65 0330 FHO 8790 991206 3 N12W49 0000 BXO 8791 991207 S15W17 plage 8792 991208 3 N17E01 0010 CSO 8793 991209 1 S17W46 0000 AXX 8794 991209 5 S13E05 0020 CSO 8795 991210 4 S13W34 0010 BXO 8796 991213 2 S27W03 0010 CRO 8797 991213 4 S35E10 0000 BXO 8798 991213 4 S14E74 0020 BXO 8799 991213 3 S08E74 0010 BXO Total number of sunspots: 37 Monthly solar data Month Average solar International sunspot Smoothed sunspot flux number number 9810 117.2 55.5 70.5 (+1.0) 9811 140.1 74.0 73.0 (+2.5) 9812 150.1 81.9 77.9 (+4.9) 9901 140.6 62.0 82.6 (+4.7) 9902 141.9 66.3 84.6 (+2.0) 9903 126.3 68.8 83.8 (-0.8) 9904 117.2 63.7 85.4 (+1.6) 9905 148.4 106.4 90.4 (+5.0) 9906 169.8 137.7 (92.5 predicted, +2.1) 9907 165.6 113.5 (94.0 predicted, +1.5) 9908 170.7 93.7 (98.9 predicted, +4.9) 9909 135.7 70.6 9910 164.8 116.4 9911 191.5 132.7 9912 155.7 (1) 45.6 (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]