Last major update issued on December 14, 2009 at 04:25 UTC.
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[Solar cycles 21-23 (last update October 4, 2007)]
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[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
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[Archived reports (last update September 13, 2009)]
The geomagnetic field was very quiet on December 13. Solar wind speed ranged between 270 and 285 km/s. The interplanetary magnetic field has been mostly southwards for many hours.
Solar flux measured at 20h UTC on 2.8 GHz was 75.5. The planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 1.6). Three hour interval K indices: 00111000 (planetary), 00112010 (Boulder).
The background x-ray flux is below the class A1 level.
At midnight there were 2 spotted regions on the visible solar disk.
Region 11034 gained a few spots and could produce a C class flare.
Spotted regions not numbered by NOAA/SWPC:
[S747] This region emerged late on December 13 to the north of region 11034. Location at midnight: N30E20
December 11-13: No partially or fully Earth directed CMEs were observed in LASCO or STEREO imagery.
Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A small recurrent coronal hole (CH387) in the northern hemisphere will be in an Earth facing position on December 14.
Processed SOHO/EIT 195 image at 23:48 UTC on December 13. The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is fair to good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet to unsettled on December 14 and quiet on December 15-17. On December 18-19 there's a chance of a few unsettled intervals due to effects from CH387.
|Coronal holes (1)||Coronal mass ejections (2)||M and X class flares (3)|
1) Effects from a coronal hole could reach Earth
within the next 5 days. When the high speed stream has arrived the
color changes to green.
2) Effects from a CME are likely to be observed at 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.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.
|Active region||Date numbered||SWPC
|Location at midnight||Area||Classification||Comment|
|Total spot count:||4||9|
flux at Earth
|International sunspot number (SIDC)||Smoothed sunspot number|
cycle 23 sunspot max.
|2009.06||68.6||2.6||(2.5 predicted, +0.2)|
|2009.07||68.2||3.5||(2.8 predicted, +0.3)|
|2009.08||67.3||0.0||(3.0 predicted, +0.2)|
|2009.09||70.5||4.2||(3.7 predicted, +0.7)|
|2009.10||72.6||4.6||(4.6 predicted, +0.9)|
|2009.11||73.6||4.2||(5.6 predicted, +1.0)|
|2009.12||72.4 (1)||2.1 (2)||(6.8 predicted, +1.2)|
1) Running average based on the
daily 20:00 UTC observed solar flux
value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SWPC) sunspot number. The official international sunspot number is typically 30-50% lower.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.