Solar Terrestrial Activity Report

Last major update issued on December 4, 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 3. Solar wind speed ranged between 575 and 751 (all day average 667) km/sec under the influence of a high speed stream from CH200. This stream appears to be ending early on Dec.4.

Solar flux measured at 20h UTC on 2.8 GHz was 101.3. The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.1)
Three hour interval K indices: 42122333 (planetary), 42133322 (Boulder).

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

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

Region 10826 decayed quickly and lost many spots in the central section. There is still a chance of an M class flare. Flares: C3.6/1F at 05:46, C3.5/1F at 08:49, C2.1 at 09:10 and C1.7 at 18:05 UTC.
Region 10828 developed a few small spots and was otherwise mostly unchanged.
Region 10829 decayed quickly and could soon become spotless.
Region 10830 was mostly unchanged. Flare: C5.3 at 07:37 UTC.

Coronal mass ejections (CMEs)

December 3: No LASCO images available.
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 this event.
December 1: No obvious fully or partly Earth directed CMEs were 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

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

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 unsettled on December 4-6.

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 poor to fair. 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) at first, then WWNN Pompano Beach FL. Propagation to the east coast of North America improved significantly, 1450 WKXW Atlantic City NJ was heard well with its ESPN programming.

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.