Solar Terrestrial Activity Report

Last major update issued on January 16, 2005 at 05:20 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 12, 2005)]

Recent activity

The geomagnetic field was quiet to major storm on January 15. Solar wind speed ranged between 527 and 706 km/sec under the influence of a high speed stream from coronal hole CH139.

Solar flux measured at 20h UTC on 2.8 GHz was 144.9. The planetary A index was 22 (STAR Ap - based on the mean of three hour interval ap indices: 22.5).
Three hour interval K indices: 36433332 (planetary), 35433332 (Boulder).

The background x-ray flux is at the class C1 level.

At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was high. A total of 17 C, 7 M and  2 X class events was recorded during the day.

Region 10718 decayed slowly, the magnetic delta structure in the trailing spot section has become much smaller. A minor M class flare is possible. Flare: M3.2 at 14:23 UTC.
Region 10720 developed slowly as the enormous penumbra elongated in the western part. The region remains very complex with multiple magnetic delta structures, two of which have very long inversion lines. Further X class flares are likely over the next several days, an X10+ flare is possible. Flares: C9.8 at 00:27, major X1.2/1B at 00:43, C2.9 at 02:39, C2.2 at 03:21, C4.2 at 03:40, M1.3 at 04:16 and major impulsive M8.4/2N at 04:33, long duration M8.6 proton event peaking at 06:38 (associated with moderate type II and IV radio sweeps and a large and fast fully Earth directed CME), C9.6 at 09:15, M1.4 at 09:30, C4.2 at 11:33, M1.2 at 11:48, C3.7 at 12:23, C7.4 at 12:31 (associated with a moderate type IV radio sweep), C3.0 at 13:44, C5.5 at 13:57, C8.0 at 16:57, C7.2 at 17:07 (associated with a weak type IV radio sweep), C2.9 at 18:02, C4.2 at 18:16, C8.8/1N at  18:53, C3.5 at 19:49, C5.4 at 20:22, M1.0 at 22:08, X2.6 long duration proton event peaking at 23:02 UTC (associated with a moderate type II radio sweep and a fast Earth directed CME).

Spotted regions not numbered by NOAA/SEC:
S496: This region emerged on January 15 in the southeast quadrant. Location at midnight: S02E27
S497: A new region emerged in the northeast quadrant late on January 15. Location at midnight: N19E15.

Coronal mass ejections (CMEs)

January 15: At least two fully Earth directed CMEs were launched during the day. The first one was associated with a long duration M8 event in region 10720 after 06h UTC. This was a fast and large CME and is likely to impact Earth during the latter half of January 16 and cause major to very severe geomagnetic storming. The second significant CME was launched during the the X2 long duration event in region 10720 late in the day. Again this was a large and fast CME and will likely reach Earth on January 17 and extend the disturbance already in progress.
January 13-14: 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 in a geoeffective position on January 9-11.

Processed SOHO/EIT 284 image at 01:06 UTC on January 16. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to unsettled during the first half of January 16. Sometime during the latter half of the day a CME is likely to impact Earth and cause major to very severe geomagnetic storming. This geomagnetic storm will continue on January 17 and be extended by another CME reaching the Earth sometime during the day. Further major CMEs are likely from region 10720 over the next days and the geomagnetic field is likely to remain at storm levels for several days. Radio propagation over polar and near polar paths will become severely degraded due to the storm and the proton levels.

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 Cristal del Uruguay and Radio Vibración (Venezuela) with weak signals. On other frequencies North American stations were noted on 930, 1050, 1510 and 1540 kHz.

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 26 25 S07W21 0360 FKI beta-gamma-delta
10720 2005.01.10 54 41 N13W03 1620 DKC delta
classification was EKC
at midnight,
area 2100
  location: N13W05
S493 emerged on
    S16W71     plage
S494 emerged on

S495 visible on

S496 emerged on
  3 S02E27 0030 CAO  
S497 emerged on
  1 N19E15 0010 AXX  
Total spot count: 80 70  
SSN: 100 110  

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 99.2 (1) 21.1 (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]