Last major update issued on December 21, 2009 at 04:30 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update October 4, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update September 13, 2009)]
The geomagnetic field was very quiet on December 20. Solar wind speed ranged between 314 and 397 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 83.7. The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.4). Three hour interval K indices: 00001100 (planetary), 11011210 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 3 spotted regions on the visible solar disk.
Region 11035 decayed further and could lose all trailing spots today.
The leader spots will rotate over the northwest limb late in the day.
Region 11036 developed slowly and quietly.
New region 11038 emerged in the northwest quadrant.
December 18-20: 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
No obvious coronal holes are currently in or near Earth facing positions.
Processed SOHO/EIT 195 image at 23:48 UTC on December 18. 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 on December 21-24.
| 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 spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 11035 | 2009.12.14 | 4 | 5 | N31W70 | 0310 | EHO | classification was EAO at midnight |
| 11036 | 2009.12.19 | 6 | 7 | S27W32 | 0010 | BXO | classification was CSO at midnight |
| 11037 | 2009.12.19 | N18E41 | |||||
| 11038 | 2009.12.20 | 2 | 2 | N16W26 | 0010 | AXX | classification was BXO at midnight |
| Total spot count: | 12 | 14 | |||||
| SSN: | 42 | 44 | |||||
| Month | Average solar flux at Earth |
International sunspot number (SIDC) | 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) |
| 2008.07 | 65.7 | 0.5 | 2.8 (-0.4) |
| 2008.10 | 68.3 | 2.9 | 1.8 (-0.5) |
| 2008.11 | 68.6 | 4.1 | 1.7 (-0.1) |
| 2008.12 | 69.2 | 0.8 | 1.7 (-) sunspot minimum |
| 2009.01 | 69.8 | 1.3 | 1.8 (+0.1) |
| 2009.02 | 70.0 | 1.4 | 1.9 (+0.1) |
| 2009.03 | 69.2 | 0.7 | 2.0 (+0.1) |
| 2009.04 | 69.7 | 1.2 | 2.2 (+0.2) |
| 2009.05 | 70.5 | 2.9 | 2.3 (+0.1) |
| 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 | 76.1 (1) | 9.4 (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.