Solar Terrestrial Activity Report

Last major update issued on January 7, 2006 at 07:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 6, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 6, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update December 6, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update December 3, 2005)]

Recent activity

The geomagnetic field was very quiet to unsettled on January 6. Solar wind speed ranged between 328 and 410 (all day average 350) km/sec. The interplanetary magnetic field was weakly southwards most of the day.

Solar flux measured at 20h UTC on 2.8 GHz was 82.0. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.3).
Three hour interval K indices: 12223211 (planetary), 13224212 (Boulder).

The background x-ray flux is at the class A2 level.

At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

New region 10845 rotated into view at the northeast limb.

Spotted regions not numbered by NOAA/SEC:
[S616] This region emerged in the northwest quadrant on January 6. Location at midnight: N07W10.
[S617] A new region emerged in the southeast quadrant on January 6. Location at midnight: S03E18. This region has the same polarity layout as would be expected from a northern hemisphere region.

Coronal mass ejections (CMEs)

January 4-6: No obviously fully or partly Earth directed CMEs were observed.

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 poorly defined trans equatorial coronal hole (CH204) could rotate to an Earth facing position on January 8.

Processed SOHO/EIT 284 image at 01:06 UTC on January 7. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be mostly quiet on January 7-12 with a possibility of unsettled intervals on January 11-12 due to effects from CH204.

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: WLAM Lewiston ME and Radio Vibración (Venezuela). Quite a few stations from the easternmost parts of Canada and USA were heard with poor to fair signals during the night. Some Cuban stations had fair signals as well, propagation further south was unusually poor.

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
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10843 2   N12W77 0010 AXX spotless
10845 2006.01.06 2 1 N18E72 0050 CAO classification was HSX at midnight, area 0040
S616 2006.01.06   1 N07W10 0000 AXX  
S617 2006.01.06   1 S03E18 0000 AXX reversed polarity?
Total spot count: 4 3  
SSN: 24 33  

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 84.4 (1) 6.1 (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]