Solar Terrestrial Activity Report

Last major update issued on January 13, 2006 at 05:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 8, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 8, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 8, 2006)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update January 8, 2006)]

Recent activity

The geomagnetic field was inactive to very quiet on January 12. Solar wind speed ranged between 276 and 342 (all day average 306) km/sec. A slight increase in geomagnetic activity was observed during the latter half of the day.

Solar flux measured at 20h UTC on 2.8 GHz was 76.5. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.8).
Three hour interval K indices: 11110001 (planetary), 12110110 (Boulder).

The background x-ray flux is well 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.

Region 10845 decayed and became spotless before midnight.

Coronal mass ejections (CMEs)

January 10-12: No obviously fully or partly Earth directed CMEs were observed.
January 13: A number 2 shaped filament - just to the west of the center of the visible disk - erupted late on January 12 (observed in EIT images beginning at 23:48 UTC) and early on January 13. Just over an hour later a fairly narrow CME was visible over the central west limb. A part of the CME could be Earth directed. 

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A trans equatorial coronal hole (CH205) was in an Earth facing position late on January 12 and on January 13.

Processed SOHO/EIT 284 image at 01:06 UTC on January 13. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet on January 13-15 becoming quiet to active during the latter half of January 15 until January 17 due to effects from CH205 and maybe even a CME.

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

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 excellent. Propagation on long distance northeast-southwest paths is very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: WLAM Lewiston ME. On other frequencies there were many stations from mostly the eastern half of North America. As an example 870 kHz had WWL New Orleans as a clear dominant. During WWL fades it was possible to hear two other stations, one with a news talk format (possibly Ithaca, NY station) and another with oldies. On 1000 kHz KOMO Seattle WA had, at times, a strong signal.

Active solar regions (Recent map)

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
10845 2006.01.06 2   N18W08 0020 HAX spotless
Total spot count: 2    
SSN: 12 0  

Monthly solar cycle data

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)
2004.11 113.2 43.5 35.3 (-0.6)
2004.12 94.5 17.9 35.2 (-0.1)
2005.01 102.2 31.3 34.6 (-0.6)
2005.02 97.2 29.2 33.9 (-0.7)
2005.03 89.9 24.5 33.5 (-0.4)
2005.04 86.0 24.4 31.6 (-1.9)
2005.05 99.3 42.6 28.9 (-2.7)
2005.06 93.7 39.6 28.8 (-0.1)
2005.07 96.4 39.9 (29.1 predicted, +0.3)
2005.08 90.5 36.4 (27.4 predicted, -1.7)
2005.09 91.1 22.1 (25.4 predicted, -2.0)
2005.10 77.0 8.5 (23.4 predicted, -2.0)
2005.11 86.3 18.0 (21.0 predicted, -2.4)
2005.12 90.7 41.2 (18.2 predicted, -2.8)
2006.01 81.1 (1) 8.3 (2) (15.2 predicted, -3.0)

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.

[DX-Listeners' Club]