Solar Terrestrial Activity Report

Last major update issued on January 27, 2004 at 03:50 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 19, 2004)]

Recent activity

The geomagnetic field was quiet to active on January 26. Solar wind speed ranged between 385 and 506 km/sec. The start of another disturbance was noted at ACE at 18:50 UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 98.0. The planetary A index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 17.5).
Three hour interval K indices: 32434443 (planetary), 32432443 (Boulder).

The background x-ray flux is at the class B1-B2 level.

At midnight there were 2 spotted regions on the visible disk. Solar flare activity was low. A total of 1 C class event was recorded during the day, this C1.6 flare at 06:12 occurred in region 10542.

Spotted regions not numbered by NOAA/SEC:
[S336] This region emerged in the northeast quadrant late on January 26. Location at midnight: N12E08.
[S337] A new region emerged in the southeast quadrant late on January 26. Location at midnight: S04E44.

Coronal mass ejections (CMEs)

January 24-26: 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.

Processed SOHO/EIT 284 image at 01:06 UTC on January 27. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active during the first half of January 27 and unsettled to active from the latter half of January 27 and on January 28 due to a high speed stream from coronal hole CH77. Quiet to unsettled is expected for January 29-30. Some time on January 31 a high speed stream from coronal hole CH78 is likely to arrive and cause unsettled to minor storm conditions until February 4.

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 poor to fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. At 02h UTC only a few weak signals were noted on the MW band with Radio Cristal del Uruguay the only station on 1470. One hour later a few of the most common stations from Brazil (on 980 and 1010 kHz) had unusually strong signals and even WWZN Boston on 1510 had a decent signal. Conditions had deteriorated somewhat by the time I posted this].

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
10542 2004.01.16 2   N06W82 0010 AXX spotless
10543 2004.01.19 1   S17W89 0010 AXX spotless before
rotating out of view
10544 2004.01.20 5   N03W76 0010 BXO spotless
S335 emerged on
    S19E20     plage
S336 emerged on
  1 N12E08 0000 AXX  
S337 emerged on
  1 S04E44 0010 AXX  
Total spot count: 8 2
SSN: 38 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)
2004.01 118.5 (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]