Solar Terrestrial Activity Report

Last major update issued on January 11, 2004 at 04:10 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 4, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 4, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 4, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update October 15, 2003)]
[Archived reports (last update January 9, 2004)]

Recent activity

The geomagnetic field was quiet to minor storm on January 10. Solar wind speed ranged between 526 and 620 km/sec. ACE data indicate the arrival of another disturbance (possibly the partial CME observed after a filament eruption on January 7) around 05h UTC. From then until 09h UTC the interplanetary magnetic field was moderately to strongly southwards and this caused minor geomagnetic storming. From 10h UTC and for the remainder of the day the IMF was mostly northwards. Early on January 11 a high speed stream from coronal hole CH75 appears to have arrived.

Solar flux measured at 20h UTC on 2.8 GHz was 119.2. The planetary A index was 24 (STAR Ap - based on the mean of three hour interval ap indices: 25.1).
Three hour interval K indices: 35543342 (planetary), 25543342 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 2 spotted regions on the visible disk. Solar flare activity was low. A total of 6 C class events was recorded during the day.

Region 10536 decayed further losing many spots and about a third of its penumbral area. The magnetic delta structure disappeared. Flares: C1.2 at 01:21, C1.9 at 03:30, C7.3/1F at 04:25, C7.7 at 05:13, C1.1 at 21:02 and C1.1 at 22:15 UTC.
Region 10537 lost some peripheral spots while slow development occurred in the main penumbrae. There is still a fairly strong magnetic delta in the central part of the region and a major flare is possible.

Coronal mass ejections (CMEs)

January 9-10: No partly or fully earth directed CMEs observed.

January 8: A partial halo CME was observed, mainly off of the east limbs, after an M1.3 flare in region 10537  at 05:07 UTC.

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

The southernmost extension of a coronal hole (CH75) in the northern hemisphere was in a geoeffective position on January 9. A recurrent trans equatorial coronal hole (CH76) will rotate into a geoeffective position on January 13-14.

Processed SOHO/EIT 284 image at 01:06 UTC on January 11. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on January 11-12 due to a high speed stream from coronal hole CH75. Quiet to unsettled is likely on January 13-15 with unsettled to minor storm conditions possible on January 16-17 because of a high speed stream from coronal hole CH76.

Long distance low 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 to poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Rafaela (Argentina) and Radio Cristal del Uruguay].

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.

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
10536 2004.01.01 30 28 S12W41 0550 EKC beta-gamma
10537 2004.01.06 16 17 N05E24 0210 DKC beta-gamma-delta
classification was DAC
at midnight
10538 2004.01.07     N05W30     plage
10539 2004.01.07     N09W11     plage
Total spot count: 46 45
SSN: 66 65

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)
2002.12 157.2 80.8 82.0 (-3.2)
2003.01 144.0 79.7 80.8 (-1.2)
2003.02 124.5 46.0 78.3 (-2.5)
2003.03 131.4 61.1 74.0 (-4.3)
2003.04 126.4 60.0 70.1 (-3.9)
2003.05 115.7 55.2 67.6 (-2.5)
2003.06 129.3 77.4 65.0 (-2.6)
2003.07 127.7 83.3 (62.0 predicted, -3.0)
2003.08 122.1 72.7 (59.4 predicted, -2.6)
2003.09 112.2 48.7 (57.5 predicted, -1.9)
2003.10 151.7 65.6 (54.7 predicted, -2.8)
2003.11 140.8 67.2 (52.0 predicted, -2.7)
2003.12 114.9 47.0 (49.4 predicted, -2.6)
2004.01 118.5 (1) 24.7 (2) (45.3 predicted, -4.1)

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 sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.

[DX-Listeners' Club]