Solar Terrestrial Activity Report

Last major update issued on January 14, 2005 at 08:10 UTC. Charts have been updated, no image update yet.

[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 active on January 13. Solar wind speed ranged between 608 and 839 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 115.6. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.0).
Three hour interval K indices: 24423333 (planetary), 24322333 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 9 C class events was recorded during the day.

Region 10718 developed significantly as an elongated area of negative polarity emerged in the trailing spots section. This caused a magnetic delta structure to form. Plarities are mixed in other parts of the region and a minor M class flare is possible. Flares: C1.0 at 01:02, C1.0 at 08:19, C1.6 at 11:26, C2.3 at 14:10, C3.3 at 16:33, C4.2 at 17:12, C2.5 at 19:05, C1.2 at 20:26 and C6.8 at 22:52 UTC.
Region 10720 developed at the same extreme rate as over the last couple of days. The region is very complex with almost all spots within a single extremely large penumbra. Extremely energetic flares are possible anytime during the next days.

Spotted regions not numbered by NOAA/SEC:
S494: This region emerged on January 13 just north of the leading penumbra in region 10718.
S495: A small region rotated into view late on January 13 at the southeast limb.

Coronal mass ejections (CMEs)

January 11-13: 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 12. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to unsettled on January 14-16.

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: Rádio Papacasa (Brazil) before 03h UTC, later on Radio Cristal del Uruguay. On other frequencies propagation was best towards Brazil and the Caribbean (WDHP 1620 and Radio Juventus Don Bosco on 1640 kHz both with fair signals).

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 19 27 S07E07 0180 FKO beta-gamma-delta
classification was FAI
at midnight, area 0240
10720 2005.01.10 38 42 N13E24 1080 DKC delta
area was 1550
at midnight
S493 emerged on
    S16W45     plage
S494 emerged on
  2 S02W02 0010 BXO
S495 visible on
  1 S07E81 0010 HRX
Total spot count: 57 73
SSN: 77 113

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]