Solar Terrestrial Activity Report

Last major update issued on January 10, 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 inactive to unsettled on January 9. Solar wind speed ranged between 443 and 536 km/sec. A weak coronal hole flow (from CH138) became the main factor of the solar wind after 18h UTC. The interplanetary magnetic field has been mostly northwards after the arrival of the flow.

Solar flux measured at 20h UTC on 2.8 GHz was 87.5. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.0).
Three hour interval K indices: 11031111 (planetary), 11030221 (Boulder).

The background x-ray flux is at the class A8 level.

At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was moderate. A total of 1 C and 1 M class event was recorded during the day.

Region 10718 did not change much. The amount of positive polarity flux near the leading negative polarity spots diminished. There is still some complexity in the trailing spots with a small negative polarity area in the southwest bordering the much larger positive polarity area. rotated fully into view. C class events are possible. Flares: long duration M2.4/1N (associated with a weak type II radio sweep) peaking at 08:51 and C2.6 at 14:47 UTC.

Coronal mass ejections (CMEs)

January 7-9: No obvious fully or partly Earth directed CMEs were observed, only a few images are currently available from January 9.

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 small, recurrent coronal hole in the southern hemisphere was in a geoeffective position on January 6-7. A large and well defined coronal hole in the northern hemisphere is probably too far to the north to become geoeffective.

Processed SOHO/EIT 284 image at 01:06 UTC on January 10. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to unsettled on January 10 with the possibility of a few active intervals due to weak coronal hole effects. Mostly quiet conditions are likely on January 11-13.

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 station tonight: At 01 UTC both WWNN Boca Raton FL and WLAM Lewiston ME were audible. One hour later Radio Cristal del Uruguay had the best signal as propagation began to favor more southerly paths. Between 05 and 06h UTC on January 9 there was a nice opening towards the southern and southeastern parts of the USA with lots of stations coming in, particularly on frequencies above 1400 kHz. At 07h UTC propagation was very different with no North American stations and only weak signals from Argentina, Uruguay and Brazil.

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     N08W82     plage
10716 2004.12.30     S13W81     plage
10718 2005.01.07 3 7 S08E54 0090 DAO classification was ESO
at midnight, area 0150
location S08E57
10719 2005.01.08 5   S09E64 0100 CAO not a separate region,
these are the trailing
spots of 10718
region should be
S493 emerged on
    S16E07     plage
Total spot count: 8 7
SSN: 28 17

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 90.2 (1) 9.3 (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]