Solar Terrestrial Activity Report

Last major update issued on December 3, 2005 at 06:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update November 9, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update November 9, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update November 9, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update December 3, 2005)]

Recent activity

The geomagnetic field was quiet to active on December 2. Solar wind speed ranged between 599 and 759 (all day average 675) km/sec under the influence of a high speed stream from CH200.

Solar flux measured at 20h UTC on 2.8 GHz was 106.3. The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.4)
Three hour interval K indices: 34332132 (planetary), 24433232 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 5 spotted regions on the visible solar disk. The solar flare activity level was high. A total of 3 C and 4 M class events was recorded during the day.

Region 10826 changed significantly as the large penumbra in the central spot section lost most of its umbra and split into smaller spots. The trailing and intermediate spot section are merging, many new small spots have emerged and a very long inversion line appears to be developing. If this development continues strong X class flares will become possible. Flares: C1.7 at 00:34, C1.3 at 02:11, major impulsive M6.5 at 02:52, C4.9 at 06:00, major M7.8/1N at 10:12 (associated with a moderate type II radio sweep), M1.0 long duration event peaking at 20:30 and M2.0 at 21:19 UTC.
Region 10828 decayed slowly in the leading spot section while some slow development was observed in the trailing spots.
New region 10829 emerged quickly in the northeast quadrant. There could be a weak magnetic delta structure in the southeastern part of the southernmost penumbra. C flares are possible.
New region 10830 rotated into view at the northeast limb. It is not yet clear if there is another region trailing this one.

Spotted region not numbered by NOAA/SEC;
[S611] This region emerged in the southeast quadrant on December 2. The spots are small and further development at this time does not appear likely.

Coronal mass ejections (CMEs)

December 2: None of the major events in region 10826 produced other than possibly very small CMEs. The unavailability of LASCO images covering the hours after the M class event during the last hours of the day makes it difficult to confirm if there was any CME caused by these events.
December 1
: No obvious fully or partly Earth directed CMEs were observed.
November 29: A partial halo CME was observed over the southern hemisphere and the northwest limb after the C4 LDE in region 10824. The core ejected material was first observed over the southwest limb in LASCO C2 images at 17:30 and in C3 at 18:18 UTC while a more diffuse front appeared soon afterwards over the south pole, the southeast quadrant and some of the northwest quadrant.

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 trans equatorial coronal hole CH200 was in an Earth facing position on November 28-30.

Processed SOHO/EIT 284 image at 13:06 UTC on December 2. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active on December 3 due to a high speed stream from CH200 and quiet to unsettled on December 4-5 barring any Earth directed CME in region 10826.

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 on long distance northeast-southwest paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). Propagation was best towards Puerto Rico and Venezuela. A few of the most usual east coast North American stations were audible at weak to fair levels.

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
10824 2005.11.20 1   S14W88 0020 AXX rotated out of view
10825 2005.11.25     S03W75     plage
10826 2005.11.28 32 62 S02E09 0490 EKC beta-gamma-delta
area was 0640 at midnight
location: S04E04
SEC location is near the easternmost edge of the region, not in the center where it should be
10827 2005.11.30     N08E29     plage
10828 2005.12.01 8 S04E29 0080 DAO location: S05E27
10829 2005.12.02 5 N11E02 0040 DSO beta-gamma
10830 2005.12.02 2 N14E78 0090 HAX location was N12E75 at midnight
S611 2005.12.02   S13E02 0010 AXX  
Total spot count: 48 84  
SSN: 98 134  

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)
2004.10 105.9 48.0 35.9 (-1.6)
2004.11 113.2 43.5 35.3 (-0.6)
2004.12 94.5 17.9 35.2 (-0.1)
2005.01 102.2 31.3 34.6 (-0.6)
2005.02 97.2 29.2 33.9 (-0.7)
2005.03 89.9 24.5 33.5 (-0.4)
2005.04 86.0 24.4 31.6 (-1.9)
2005.05 99.3 42.6 28.9 (-2.7)
2005.06 93.7 39.6 (28.1 predicted, -0.8)
2005.07 96.4 39.9 (27.6 predicted, -0.5)
2005.08 90.5 36.4 (25.7 predicted, -1.8)
2005.09 91.1 22.1 (23.6 predicted, -2.1)
2005.10 77.0 8.5 (21.6 predicted, -2.0)
2005.11 86.3 18.0 (19.2 predicted, -2.4)
2005.12 102.3 (1) 5.7 (2) (16.4 predicted, -2.8)

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% lower.

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]