Solar Terrestrial Activity Report

Last major update issued on December 2, 2004 at 05:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update November 4, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update November 4, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update November 4, 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 quiet to minor storm on December 1. Solar wind speed ranged between 506 and 705 km/sec under the influence of a high speed stream from coronal hole CH129. Solar wind speed decreased gradually after noon. 

Solar flux measured at 20h UTC on 2.8 GHz was 111.0. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 12.8).
Three hour interval K indices: 13521212 (planetary), 13422223 (Boulder).

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

At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was moderate. A total of 5 C and 1 M class events was recorded during the day.

Region 10706 was quiet and stable.
Region 10707 decayed in the western and northern parts while development was observed in the south and in the east. C flares are likely and there is a minor possibility of small M class flares. Flares: C1.9 at 01:45, C1.3 at 13:06, C2.6 at 16:03, C4.2 at 16:19 and C1.5 at 18:30 UTC.
Region 10708 developed a few small trailing spots and the single penumbra become somewhat elongated. Flare: M1.1 long duration event peaking at 07:20 UTC. This event was associated with a weak type IV radio sweep and a full halo CME.

Coronal mass ejections (CMEs)

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.
November 29-30: No obviously 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 well defined coronal hole in the southeast quadrant is probably too far to the south to become geoeffective. Recurrent coronal hole CH130 in the northern hemisphere was in a geoeffective position on November 30 and December 1. Recurrent trans equatorial coronal hole CH131 will likely rotate into a geoeffective position on December 5.

Processed SOHO/EIT 284 image at 13:06 UTC on December 1. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to quiet to unsettled on December 2. On December 3 a weak flow from coronal hole CH130 could arrive and cause mostly unsettled conditions that day and on December 4. On December 4 the CME observed on December 1 is likely to arrive and cause some unsettled and active intervals.

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. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela). On other frequencies quite a few weak signals from North America were noted, only two stations had good signals: CJYQ on 930 kHz and Greenland on 650 kHz.

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 2 2 S07W21 0080 HSX  
10707 2004.11.24 16 15 S17W24 0240 DSC beta-gamma
classification was DAC
at midnight, area 0170
10708 2004.11.26 4 4 N09E14 0130 CSO  
S485 emerged on
    S04W81     plage
Total spot count: 22 21
SSN: 52 51

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)
2004.12 111.0 (1) 1.7 (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]