Last major update issued on December 17, 2007 at 05:05 UTC.
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The geomagnetic field was quiet on December 16. Solar wind speed ranged between 344 and 393 km/s (average speed was 356 km/s, decreasing 75 km/s from the previous day). A high speed stream from CH304 arrived early on December 17 (at 02:02 UTC at SOHO).
Solar flux measured at 20h UTC on 2.8 GHz was 81.7. 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: 10000002 (planetary), 01001112 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day.
Region 10978 decayed slowly losing spots and penumbral area. The opposite polarity areas are poorly separated in the central part of the region and further C class flares are possible. Flare: C1.2 at 03:55 UTC.
December 14-16: No obvious fully or partly Earth directed CMEs were observed in incomplete 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 very large recurrent coronal hole (CH304) in the southern hemisphere will rotate into an Earth facing position on December 14-18.
Processed SOHO/EIT 195 image at 00:12 UTC on December 17. 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. Propagation on long distance northeast-southwest paths is poor.
Monitoring remarks from a location near N58E06: December 8: Excellent signals were noted on nearly all TA frequencies during my local morning. Stations like 1290 CJBK and 1330 WLOL had huge signals. The Vancouver stations on 1320 and 1470 were occasionally very good. The best Trans Atlantic propagation sector was 290-320 degrees.
The geomagnetic field is expected to be quiet to major storm on December 17 and quiet to active on December 18-22 due to effects from CH304.
|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|
|10978||2007.12.06||18||17||S10W65||0240||DAI||classification was DAI at midnight, area 0090|
|Total spot count:||18||17|
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||83.3 (1)||15.4 (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/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.