Solar Terrestrial Activity Report

Last major update issued on January 12, 2005 at 03:40 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 active on January 11. Solar wind speed ranged between 388 and 464 km/sec. A moderately high speed stream from coronal hole CH138 ended at about 14h UTC. At about 20h UTC a strong high speed stream from coronal hole CH139 arrived at ACE.

Solar flux measured at 20h UTC on 2.8 GHz was 94.2. The planetary A index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 14.0).
Three hour interval K indices: 14422323 (planetary), 14422323 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day.

Region 10718 developed slowly. The region became more complex as positive polarity flux emerged just ahead of the leading negative polarity spots. C flares are likely. Further development will increase the likelihood of M class flares with associated Earth directed CMEs. Flares: C1.4 at 16:16 and C1.1 at 23:29 UTC.
Region 10720 developed extremely quickly and already has the potential to produce M class flares. This is a compact region with little separation between the opposite polarity areas. A magnetic delta structure could easily form in the northern central part of the region if the current rate of development is sustained.

Coronal mass ejections (CMEs)

January 9: A large partial halo CME was observed in LASCO images after the M2 event in region 10718 at 08:51 UTC.
January 10-11
: No obvious 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

An extension (CH139) of a large coronal hole in the northern hemisphere was likely in a geoeffective position on January 9-11.

Processed SOHO/EIT 284 image at 01:06 UTC on January 12. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be unsettled to major storm on January 12 and quiet to minor storm on January 13-14 due to a high speed stream from coronal hole CH139. A flanking impact from the CME observed on January 9 is possible on January 12.

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 very poor. Propagation along long distance north-south paths is fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and an unidentified station from Brazil. On other frequencies propagation was best towards Brazil. CBN Aracajú on 930 kHz had an unusually good 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
10718 2005.01.07 2 13 S06E32 0070 DAO classification was EAO
at midnight, area 0200
10719 2005.01.08           this region was deleted
on January 11
10720 2005.01.10 3 21 N13E52 0050 CAO classification was DAC
at midnight, area 0170
location: N13E63
S493 emerged on
    S16W19     plage
Total spot count: 5 34
SSN: 25 54

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 90.6 (1) 11.4 (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]