Last major update issued on December 17, 2006 at 06:05 UTC.
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(last update November 12, 2006)]
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The geomagnetic field was quiet to active on December 16. Solar wind speed ranged between 547 and 791 km/s (all day average 606 km/s - decreasing 95 km/s from the previous day). A weak solar wind shock was observed at 17:42 UTC at SOHO. This was the arrival of the CME associated with the X1 flare late on December 14. The interplanetary magnetic field has been predominantly northwards since the arrival of the CME causing only a weak geomagnetic disturbance.
Solar flux measured at 20h UTC on 2.8 GHz was 82.3. The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.4). Three hour interval K indices: 34110243 (planetary), 24211233 (Boulder).
The background x-ray flux is at the class A4 level.
At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10930 decayed and lost its magnetic delta structure. A minor M
class flare is a possibility until the region rotates behind the west limb on
Dec.18.
December 14: A full halo CME was observed in association with the X1
flare.
December 15-16: No obvious partly or fully Earth directed CMEs
were detected in LASCO 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
Recurrent coronal hole CH252 (southern hemisphere with a trans equatorial extension) will be in an Earth facing position on December 16-17.
Processed SOHO/EIT 195 image at 16:48 UTC on December 15. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on December 17-18. A high speed stream from CH252 could cause unsettled to minor storm conditions on December 19-21.
| 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 very poor. Propagation on long distance northeast-southwest paths is poor.
Monitoring remarks from a location near N58E06: Very few trans Atlantic stations were audible at 04 and 05h UTC and none from North America. 1520 Radio Voz (Puerto Rico) had a weak signal but was nevertheless the stations with the best signal.
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 spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10930 | 2006.12.04 | 10 | 8 | S06W72 | 0480 | DKC | beta-gamma classification was DKI at midnight |
| Total spot count: | 10 | 8 | |||||
| SSN: | 20 | 18 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2005.09 | 91.1 | 21.9 | 25.8 (-1.6) |
| 2005.10 | 77.0 | 8.7 | 25.5 (-0.3) |
| 2005.11 | 86.3 | 18.0 | 24.9 (-0.6) |
| 2005.12 | 90.7 | 41.1 | 23.0 (-1.9) |
| 2006.01 | 83.4 | 15.3 | 20.8 (-2.2) |
| 2006.02 | 76.5 | 4.9 | 18.6 (-2.2) |
| 2006.03 | 75.4 | 10.6 | 17.3 (-1.3) |
| 2006.04 | 89.0 | 30.2 | 17.1 (-0.2) |
| 2006.05 | 80.9 | 22.2 | 17.3 (+0.2) |
| 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 | 92.8 (1) | 18.0 (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.
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