Solar Terrestrial Activity Report

Last major update issued on January 13, 2004 at 04:55 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 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 unsettled on January 12. Solar wind speed ranged between 457 and 556 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 118.3. The planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 11.1).
Three hour interval K indices: 22123333 (planetary), 12012233 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight there were 3 spotted regions on the visible disk. Solar flare activity was low. A total of 4 C class events was recorded during the day.

Region 10536 decayed further losing about a third of its penumbral area. The region will rotate over the southwest limb on January 14. A minor M class flare is still possible. Flares: C1.6 at 03:48, C1.8 at 08:40 and C1.1 at 15:06 UTC.
Region 10537 had the westernmost penumbra merging with the main penumbra. There is still a magnetic delta in the southeastern part of this penumbra and an M flare is possible.
New region 10540 rotated into view at the southeast limb. Early magnetograms indicate the presence of both polarities within the visible penumbra, however, the region will have to rotate into better view to determine if there is a magnetic delta. Flare: C1.1 at 19:17 UTC.

Coronal mass ejections (CMEs)

January 12: A CME was observed over the northwest limb, the north pole and part of the northeast limb late in the day. This slow CME was probably associated with an erupting filament in the northwest quadrant.

January 11: A CME was observed off of the southeast limb during the evening, it probably had a backsided origin. 

January 10: 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) will rotate into a geoeffective position on January 14-16, the coronal hole is well defined in the northern and central parts.

Processed SOHO/EIT 284 image at 01:06 UTC on January 13. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to unsettled on January 13-15 with unsettled to minor storm conditions possible from late on January 16 until January 18 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 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 on the southwesterly antenna with a strong and clear signal, Radio Vibración (Venezuela) on the EWEs directed to the west and northwest. Lots of carriers noted on TA frequencies, several US and Canadian east coast stations had fair signals. Radio Corporación (Chile) on 1380 was unusually strong].

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 25 13 S12W68 0250 EKI beta-gamma
classification was DKC
at midnight
10537 2004.01.06 16 15 N05W03 0240 DKC beta-gamma-delta
10538 2004.01.07     N05W56     plage
10539 2004.01.07     N09W37     plage
10540 2004.01.12 6 3 S11E76 0060 HHX classification was CAO
at midnight, area 0100
SEC classification not
possible with the
stated area
Total spot count: 47 31
SSN: 77 61

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) 28.9 (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]