Last major update issued on December 8, 2007 at 04:30 UTC.
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The geomagnetic field was very quiet on December 7. Solar wind speed ranged between 277 and 344 km/s (average speed was 317 km/s, decreasing 27 km/s from the previous day).
Solar flux measured at 20h UTC on 2.8 GHz was 82. The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 0.9). Three hour interval K indices: 01000000 (planetary), 01000001 (Boulder).
The background x-ray flux is at the class A3 level.
At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10978 developed further with a significant increase in penumbral area and spots. A C class flare is likely.
Spotted regions not numbered by NOAA/SWPC:
[S713] This region emerged in the northwest quadrant on December 6 and decayed slowly on December 7. Location at midnight: N08W52
[S714] This region emerged on December 7 to the northwest of region 10978. Location at midnight: S05E42
December 5-7: No obvious fully or partly Earth directed CMEs were observed in LASCO imagery.
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 recurrent trans equatorial coronal hole (CH303) will rotate into an Earth facing position on December 8-11.
Processed SOHO/EIT 195 image at 00:00 UTC on December 8. 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 good to very good. Propagation on long distance northeast-southwest paths is poor.
Monitoring remarks from a location near N58E06: November 12: During the evening fairly strong signals from east coast USA stations. 1470 WJDY, 1500 WFIF and 1520 WIZZ were all good on their daytime power. The best Trans Atlantic propagation sector was 270-310 degrees.
The geomagnetic field is expected to be quiet on December 8-10. Quiet to active conditions are likely on December 11-14 due to effects from CH303, there's a chance of isolated minor storm intervals on December 11 and 12.
|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/SEC. 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 SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
|Active region||Date numbered||SEC
|Location at midnight||Area||Classification||Comment|
|10978||2007.12.06||14||27||S09E54||0090||DAO||classification was DAI at midnight, area 0200|
|Total spot count:||14||30|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2007.06||73.7||12.0||(7.5 predicted, -1.2)|
|2007.07||71.6||10.0||(6.7 predicted, -0.8)|
|2007.08||69.1||6.2||(6.1 predicted, -0.6)|
|2007.09||67.1||2.4||(6.2 predicted, +0.1)|
|2007.10||67.4||0.9||(6.7 predicted, +0.5)|
|2007.11||69.6||1.7||(7.3 predicted, +0.6)|
|2007.12||75.2 (1)||4.2 (2)||(7.6 predicted, +0.3)|
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/SEC) 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.