Solar Terrestrial Activity Report

Last major update issued on December 4, 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 December 3, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 3, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update December 3, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update November 8, 2004)]
[Archived reports (last update December 1, 2004)]

Recent activity

The geomagnetic field was inactive to very quiet on December 3. Solar wind speed ranged between 368 and 451 km/sec, gradually decreasing all day.

Solar flux measured at 20h UTC on 2.8 GHz was 100.8. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.3).
Three hour interval K indices: 01101111 (planetary), 01102220 (Boulder).

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

At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10706 decayed slowly and quietly.
Region 10707 decayed slowly and quietly.
Region 10708 was mostly unchanged. C flares are still possible.

Coronal mass ejections (CMEs)

December 3: A full halo CME was observed in LASCO C3 images beginning at 00:42 UTC. This CME was fast and aimed squarely at Earth. An impact is likely sometime between 18 UTC on December 4 and 03 UTC on December 5.
December 2
: No obviously Earth directed CMEs observed.
December 1
: A full halo CME was observed after an M1 event in region 10708 during the morning. The CME was best defined over the northeast limb, however, faint material movement was observed in all other directions in LASCO C3 images. Another and slower CME with a source well behind the northwest limb was observed at the same time.

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

Recurrent coronal hole CH130 in the northern hemisphere was in a geoeffective position on November 30 and December 1. Small and recurrent trans equatorial coronal hole CH131 will likely rotate into a geoeffective position on December 5.

Processed SOHO/EIT 284 image at 01:06 UTC on December 4. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be initially very quiet on December 4. A coronal hole flow could arrive during the day and cause unsettled conditions. Late in the day a CME impact is expected and geomagnetic activity will probably increase to active to major storm levels. On December 6-7 quiet to unsettled conditions are likely.

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.


Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela), WWNN Pompano Beach FL and WLAM Lewiston ME, all with fairly weak signals. On other frequencies mostly stations from North America and northern South America could be heard, no signals were particularly impressive.

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
10706 2004.11.24 3 1 S06W48 0080 CAO classification was HSX
at midnight, area 0050
location: S08W50
10707 2004.11.24 9 4 S14W49 0190 DAO classification was DSO
at midnight, area 0070
location: S16W52
10708 2004.11.26 5 4 N08W12 0160 CSO area was 0110
at midnight
location N10W14
10709 2004.12.03 1   N06E61 0020 AXX spotless
no spots observed
during the day in
any available image
Total spot count: 18 9
SSN: 58 39

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)
2003.10 151.7 65.5 58.2 (-1.3)
2003.11 140.8 67.3 56.7 (-1.5)
2003.12 114.9 46.5 54.8 (-1.9)
2004.01 114.1 37.3 52.0 (-2.8)
2004.02 107.0 45.8 49.3 (-2.7)
2004.03 112.0 49.1 47.1 (-2.2)
2004.04 101.2 39.3 45.5 (-1.6)
2004.05 99.8 41.5 43.9 (-1.6)
2004.06 97.4 43.2 (42.2 predicted, -1.7)
2004.07 119.1 51.0 (40.6 predicted, -1.6)
2004.08 109.6 40.9 (39.0 predicted, -1.6)
2004.09 103.1 27.7 (37.1 predicted, -1.9)
2004.10 105.9 48.4 (34.9 predicted, -2.2)
2004.11 113.2 43.7 (33.0 predicted, -1.9)
2004.12 105.8 (1) 5.7 (2) (30.7 predicted, -2.3)

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 some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.

[DX-Listeners' Club]