Solar Terrestrial Activity Report

Last major update issued on January 6, 2005 at 04:50 UTC.

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

Recent activity

The geomagnetic field was quiet to minor storm on January 5. Solar wind speed ranged between 560 and 774 km/sec under the influence of a high speed stream from coronal hole CH136. Solar wind speed has decreased steadily since 13h UTC as the coronal hole flow is coming to its end.

Solar flux measured at 20h UTC on 2.8 GHz was 88.2. The planetary A index was 21 (STAR Ap - based on the mean of three hour interval ap indices: 20.8).
Three hour interval K indices: 54543312 (planetary), 44443321 (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 10715 decayed slowly and quietly.

Coronal mass ejections (CMEs)

January 5: Two CMEs of interest were observed during the day. The first was a very faint partial halo CME where most of the ejected material was observed over the west limbs. Its source was probably a filament eruption (associated with a B class long duration x-ray event) near region 10715. This event occurred approximately between 04 and 06h UTC. The second CME is more interesting as it was more obvious, full halo, and likely has a larger potential for causing a geomagnetic disturbance. Its source was a fairly large filament eruption in the northeast quadrant near 14h UTC. The coronal hole image below outlines the filament as it is about to erupt, the shape of the filament is an elongated number 2.
January 4
: An extremely faint and slow full halo CME was observed in LASCO C3 images after noon. This CME was likely associated with a C7 flare in region 10715.
January 3
: An extremely faint and slow full halo CME was observed in LASCO C3 images after 09h UTC. If there was a frontsided source the only candidate would have been the C3 LDE in region 10715 a few hours earlier. 

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 recurrent coronal hole in the southern hemisphere will likely be in a geoeffective position on January 6. The associated high speed stream could become geoeffective on January 9.

Processed SOHO/EIT 284 image at 13:06 UTC on January 5. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to unsettled on January 6-7. Weak CME impacts are possibly both days and could cause occasional active intervals. A more significant CME is likely to arrive on January 8 and may cause unsettled to minor storm conditions. Quiet to active is possible on January 9 both due to this CME and the arrival of a coronal hole flow from CH138.

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) Material from a CME is likely to impact 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 along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) and WWNN Boca Raton FL, both with weak signals. Propagation towards North America seems to be recovering quickly with several stations noted above 1400 kHz and at least one station on each 10 kHz spacing in the 1650-1700 kHz interval.

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
10715 2004.12.28 5 4 N04W33 0030 DRO classification was CSO
at midnight
10716 2004.12.30     S13W29     plage
Total spot count: 5 4
SSN: 15 14

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)
2003.11 140.8 67.3 56.7 (-1.5)
2003.12 114.9 46.5 54.8 (-1.9)
2004.01 114.1 37.3 52.0 (-2.8)
2004.02 107.0 45.8 49.3 (-2.7)
2004.03 112.0 49.1 47.1 (-2.2)
2004.04 101.2 39.3 45.5 (-1.6)
2004.05 99.8 41.5 43.9 (-1.6)
2004.06 97.4 43.2 41.7 (-2.2)
2004.07 119.1 51.0 (39.6 predicted, -1.9)
2004.08 109.6 40.9 (38.0 predicted, -1.6)
2004.09 103.1 27.7 (36.1 predicted, -1.9)
2004.10 105.9 48.4 (33.9 predicted, -2.2)
2004.11 113.2 43.7 (32.0 predicted, -1.9)
2004.12 94.5 17.9 (29.7 predicted, -2.3)
2005.01 93.9 (1) 6.2 (2) (27.0 predicted, -2.7)

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% less.

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]