Last major update issued on December 22, 2006 at 05:15 UTC.
geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update November 12, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update November 12, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update November 12, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update December 18, 2006)]
The geomagnetic field was quiet to active on December 21. Solar wind speed ranged between 569 and 845 km/s (all day average 682 km/s - increasing 32 km/s over the previous day) under the influence of a high speed stream from CH252.
Solar flux measured at 20h UTC on 2.8 GHz was 72.3. The planetary A index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 14.0). Three hour interval K indices: 43433221 (planetary), 43433321 (Boulder).
The background x-ray flux is far below the class A1 level.
At midnight the visible solar disk was spotless. The solar flare activity level was very low. No C class events were recorded during the day.
December 19-21: No obvious partly or fully Earth directed CMEs were detected 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
Recurrent coronal hole CH252 (southern hemisphere with a trans equatorial extension) was in an Earth facing position on December 16-20.
Processed SOHO/EIT 195 image at 00:00 UTC on December 22. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on December 22 and quiet to unsettled on December 23 due to effects from CH252. Quiet conditions are likely on December 24-27.
|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.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is very poor.
Monitoring remarks from a location near N58E06: A few stations from Venezuela and the Canadian Atlantic provinces were weakly audible at times. The best TA signal was from Greenland on 650 kHz which reached a fair to good signal level.
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|
|Total spot count:||0||0|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2006.06||76.5||13.9||(16.3 predicted, -1.0)|
|2006.07||75.7||12.2||(14.7 predicted, -1.6)|
|2006.08||79.0||12.9||(14.2 predicted, -0.5)|
|2006.09||77.8||14.5||(14.1 predicted, -0.1)|
|2006.10||74.3||10.4||(13.0 predicted, -1.1)|
|2006.11||86.3||21.5||(11.5 predicted, -1.5)|
|2006.12||88.5 (1)||18.4 (2)||(11.3 predicted, -0.2)|
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/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.