Solar Terrestrial Activity Report

Last major update issued on January 4, 2005 at 04:20 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 2, 2005)]

Recent activity

The geomagnetic field was quiet to minor storm on January 3. Solar wind speed ranged between 570 and 736 km/sec. It now appears likely that the full halo CME observed right after midnight on January 1 reached Earth on January 2 and was the main contributor to the unusually high solar wind speed recorded that day. The combination of a high speed stream and a high speed CME made it difficult to interpret the data correctly. The high speed stream from coronal hole CH136 has been the main source of geomagnetic activity since the morning of January 3.

Solar flux measured at 20h UTC on 2.8 GHz was 94.2. The planetary A index was 22 (STAR Ap - based on the mean of three hour interval ap indices: 21.6).
Three hour interval K indices: 44335432 (planetary), 34335422 (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 10717 behind the northwest limb was the source of a C1.1 at 09:39 and a C1.1 flare at 11:09 UTC.

Region 10715 decayed significantly and simplified. C flares are possible. Flare: long duration C3.8 event peaking at 04:22 UTC.
Region 10716 decayed and could become spotless today.

Coronal mass ejections (CMEs)

January 3: An extremely faint and slow full halo CME was observed in LASCO C3 images after 09h UTC. If there was a frontsided source the only candidate would have been the C3 LDE in region 10715 a few hours earlier. 
January 2
: No obviously Earth directed CMEs were observed.
January 1
: A large and partially Earth directed CME is likely to have been associated with the X1.7 event early in the day and could reach Earth during the first half of January 3.

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

Recurrent large trans equatorial coronal hole CH136 was in a geoeffective position on December 31-January 2.

Processed SOHO/EIT 284 image at 19:06 UTC on January 3. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on January 4-5 due to coronal hole effects. Quiet to unsettled is likely on January 6-7.

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: RadioVibración (Venezuela) with a weak signal, several other weak signals could be heard as well. From North America CJYQ on 930 and VOWR on 800 kHz had the best 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
10715 2004.12.28 16 11 N04W04 0130 DAI beta-gamma
area was 0090
at midnight
10716 2004.12.30 7 1 S13W01 0030 CAO classification was AXX
at midnight, area 0000
Total spot count: 23 12
SSN: 43 32

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 97.7 (1) 4.7 (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]