Solar Terrestrial Activity Report

Last major update issued on January 29, 2004 at 04:20 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 minor storm on January 28. Solar wind speed ranged between 456 and 599 km/sec under the influence of a high speed stream from coronal hole CH77.

Solar flux measured at 20h UTC on 2.8 GHz was 88.5. The planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 20.0).
Three hour interval K indices: 54433332 (planetary), 54533332 (Boulder).

The background x-ray flux is at the class A6 level.

At midnight there was 1 spotted region on the visible disk. Solar flare activity was very low.

Spotted regions not numbered by NOAA/SEC:
[S339] This small region rotated into view at the southeast limb. Location at midnight: S12E78.

Coronal mass ejections (CMEs)

January 26-28: 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 coronal hole (CH78) in the northern hemisphere will rotate into a geoeffective position on January 28 - February 2. 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 19:06 UTC on January 28. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet on 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 5.

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 good. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay with an unusually strong signal. During brief weaker periods Radio Rafaela could be heard. An unidentified station from Argentina, probably Radio Champaqui, was noted on 1510 kHz before 04h UTC with a surprisingly good signal. Other impressive signals observed from Radio Real (Uruguay) on 1590, Radio Corporación (Chile) on 1380 and Rádio Nacional (Brazil) - S9+22dB - on 980 kHz].

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
S335 emerged on
    S19W06     plage
S336 emerged on
    N12W18     plage
S337 emerged on
    S04E18     plage
S338 emerged on
    N16E05     plage
S339 visible on
  2 S12E78 0020 HAX  
Total spot count: 0 2
SSN: 0 12

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)
2004.01 116.5 (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]