Solar Terrestrial Activity Report

Last major update issued on January 18, 2004 at 06:30 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 January 16, 2004)]
[Archived reports (last update January 9, 2004)]

Recent activity

The geomagnetic field was quiet to active on January 17. Solar wind speed ranged between 547 and 738 km/sec, gradually decreasing all day under the influence of a high speed stream from coronal hole CH76.

Solar flux measured at 20h UTC on 2.8 GHz was 122.6. The planetary A index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 15.4).
Three hour interval K indices: 32343333 (planetary), 33342333 (Boulder).

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

At midnight there were 3 spotted regions on the visible disk. Solar flare activity was high. A total of 7 C and 1 M class events was recorded during the day.

Region 10537 decayed slowly and rotated to the northwest limb. Flare: C1.2 at 09:44 UTC.
Region 10540 decayed slightly, however, the region became unstable and produced quite a few flares. Flares: C1.6 at 03:48, C1.0 at 08:01, C1.4 at 09:16, C1.5 at 12:49, C1.1 at 15:17, major impulsive M5.0 at 17:50 and C1.2 at 20:52 UTC. The major flare was associated with a moderate type II radio sweep. This region was the source of an impulsive M1.5 flare at 00:14 UTC on January 18.
Region 10541 decayed slowly and was quiet.

There is an unusually large and dense J-shaped filament in the northeast quadrant and rotating into the northwest quadrant, it is trailing coronal hole CH76 and has nearly the same shape. An eruption of this filament will cause a large CME.

Coronal mass ejections (CMEs)

January 18: The M1 flare early in the day in region 10540 was likely associated with an earth directed CME. No LASCO images are yet available to confirm this.

January 17: The major M5 flare in region 10540 was likely associated with an earth directed CME. No LASCO images are yet available to confirm this.

January 15-16: No partly or fully earth directed CMEs 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

A recurrent trans equatorial coronal hole (CH76) was in a geoeffective position on January 13-17.

Processed SOHO/EIT 284 image at 01:06 UTC on January 18. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on January 18-19 due to a high speed stream from coronal hole CH76. Two CMEs from flares in region 10540 on January 17/18 could arrive late on January 19 or early on January 20 and cause active to minor storm conditions. Quiet to unsettled is likely on January 21-22.

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. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Rafaela (Argentina). At times there were interference from a few stations from Brazil.].

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
10537 2004.01.06 3 5 N04W70 0170 DAO area was 0080
at midnight
10540 2004.01.12 9 19 S14E15 0350 ESO  
10541 2004.01.15 3 3 S09W31 0060 DAO  
10542 2004.01.16 1   N11E43 003 HSX spotless
Total spot count: 16 27
SSN: 56 57

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)
2004.01 119.0 (1) 37.4 (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]