Solar Terrestrial Activity Report [Planetary A Index, Solar Flux and SEC sunspot number] Last update December 13, 1999 at 04:20 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 unsettled on December 12. Solar wind speed ranged between 356 and 806 km/sec. A solar wind shock was observed at ACE at 15:10 UTC. Solar wind speed abruptly increased from 380 to 590 km/sec and increased to above 800 km/sec within two hours. Wind speed then decreased fairly quickly and is currently near 500 km/sec. The interplanetary magnetic field was not as impressive as solar wind speed. Isolated episodes of a strong southward orientation were observed early on but settled down weakly to moderately strong southward. The origin of the disturbance is uncertain (as LASCO images have not been updated since Dec.7) but is likely to have occurred within 2 days before the impact given the unusually high solar wind speed. Solar flare activity was very low. Solar flux was 159.2, the planetary A index was 9 (3-hour Kp indices: 1313 2332, Boulder K indices: 1313 2432). Region 8785 was quiet and stable, the region will rotate off the visible disk on Dec.14. Region 8787 decayed into spotless plage. Region 8788 decayed slowly and was quiet. Region 8790 is decaying quickly and could become spotless today or tomorrow. Region 8792 was quiet and stable, as was region 8793. Regions 8794 and 8795 were quiet and stable. An active region is rotating into view at the southeast limb. A couple of active regions could be emerging in the southeast quadrant. Flares and CMEs No C flares were recorded on December 12. The background x-ray flux is at the class B5 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 13-14. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is generally 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 at region numbered sunspots midnight Area Classification Comment 8785 991201 2 N14W73 0080 CAO 8787 991202 N17W85 plage 8788 991202 7 N10W51 0380 FHO 8790 991206 7 N12W35 0010 BXO 8791 991207 S15W04 plage 8792 991208 4 N17E16 0030 CAO 8793 991209 1 S17W33 0000 AXX 8794 991209 2 S14E19 0030 CSO 8795 991210 4 S13W21 0040 DAO Total number of sunspots: 27 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 154.8 (1) 40.8 (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]