Solar Terrestrial Activity Report

Last major update issued on January 11, 2005 at 03:55 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 on January 10. Solar wind speed ranged between 370 and 545 km/sec under the influence of weak effects from coronal hole CH138.

Solar flux measured at 20h UTC on 2.8 GHz was 90.1. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.8).
Three hour interval K indices: 11112222 (planetary), 01212223 (Boulder).

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

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 1 C class event was recorded during the day.

Region 10718 decayed slowly in the trailing spot section. The surrounding plage cooled as well. There is still a small area of negative polarity in the southwestern part of the trailing spot section. Other than that the region has a simple layout with negative polarity in the west and positive polarity in the east. Flare: C1.0 at 22:15 UTC.
New region 10720 emerged in the northeast quadrant. This is a compact region with hot plage and little separation between the opposite polarity area. Further development will make C flares likely.

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 8 and 10
: 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 10.

Processed SOHO/EIT 284 image at 13:06 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 11-14 with the possibility of a few active intervals due to weak coronal hole effects. 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 station tonight: Radio Vibración (Venezuela) at first, then Radio Cristal del Uruguay. On other frequencies propagation was best towards Brazil. Both Rádio CBN and Rádio Metropolitana had nice signals on 930 kHz. The only North American station noted was WWZN on 1510 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 3 6 S08E44 0100 DAO classification was EAO
at midnight, area 0160
10719 2005.01.08 4   S10E52 0070 DSO not a separate region,
these are the trailing
spots of 10718
region should be
10720 2005.01.10 3 4 N09E65 0010 BXO classification was DRO
at midnight, area 0030
location: N13E63
S493 emerged on
    S16W06     plage
Total spot count: 10 10
SSN: 40 30

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) 10.6 (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]