Solar Terrestrial Activity Report

Last major update issued on December 10, 2005 at 05:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 6, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 6, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update December 6, 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 inactive to unsettled on December 9. Solar wind speed ranged between 278 and 322 (all day average 302) km/sec. An unexpected disturbance began at ACE just after 18h UTC. While solar wind density increased wind speed was still very low, so this disturbance appears to be caused by excess coronal mass carried along by the solar wind. Currently the geomagnetic field is quiet to active.

Solar flux measured at 20h UTC on 2.8 GHz was 89.1. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.6)
Three hour interval K indices: 10001113 (planetary), 10011223 (Boulder).

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

At midnight there were 5 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 10830 was quiet and stable.
Region 10832 decayed quickly and will likely rotate out of view at the southwest limb late today.
New region 10833 emerged in the southwest quadrant.
New region 10834 rotated into view at the southeast limb.
New region 10835 rotated into view at the northeast limb.

Coronal mass ejections (CMEs)

December 7-9: No obvious partly or fully Earth directed CMEs were observed in incomplete imagery.

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

No obvious coronal holes are currently in or near Earth facing positions.

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

Forecast

The geomagnetic field is expected to be quiet to active on December 10 and quiet on December 11-12.

Coronal holes (1)	Coronal mass ejections (2)	M and X class flares (3)

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor to poor. Propagation on long distance northeast-southwest paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: WWNN Pompano Beach FL at 02h UTC, later Radio Vibración (Venezuela) as propagation deteriorated quickly.

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.

Monthly solar cycle data

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.