Solar Terrestrial Activity Report

Last major update issued on January 28, 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 January 16, 2004)]
[Archived reports (last update January 27, 2004)]

Recent activity

The geomagnetic field was quiet to active on January 27. Solar wind speed ranged between 383 and 543 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 93.7. The planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 16.9).
Three hour interval K indices: 34233333 (planetary), 34223333 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight there were 2 spotted regions on the visible disk. Solar flare activity was very low.

Spotted regions not numbered by NOAA/SEC:
[S335] This region emerged in the southeast quadrant on January 25, then became spotless before reemerging on January 27. Location at midnight: S19E07.
[S338] A new region emerged on a coronal island inside coronal hole CH78 on January 27. The region was decaying slowly late in the day and could soon become spotless. Location at midnight: N16E18.

Coronal mass ejections (CMEs)

January 25-27: No partly or fully earth directed CME 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 (CH77) was in a geoeffective position on January 24-25. A recurrent coronal hole (CH78) in the northern hemisphere will rotate into a geoeffective position on January 28 - February 1. Another coronal hole (CH79) in the southern hemisphere is the southern part of what was coronal hole CH74 during the previous rotation.

Processed SOHO/EIT 284 image at 01:06 UTC on January 28. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be unsettled to minor storm on January 28 due to a high speed stream from coronal hole CH77. Quiet to unsettled is expected for January 29-30. On January 31 a high speed stream from coronal hole CH78 is likely to arrive and cause unsettled to minor storm conditions lasting until February 4.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor to poor. Propagation along long distance north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay with an occasionally good signal. Only a few other TA signals noted in the MW band].

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
10544 2004.01.20     N03W89     plage
S335 emerged on
  1 S19E07 0010 HRX  
S336 emerged on
    N12W05     plage
S337 emerged on
    S04E31     plage
S338 emerged on
  1 N16E18 0000 AXX  
Total spot count: 0 2
SSN: 0 22

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)
2004.01 117.6 (1) 57.6 (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]