Solar Terrestrial Activity Report

Last update December 12, 2002 at 03:05 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 2, 2002)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 2, 2002)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update December 2, 2002)]
[Historical solar and geomagnetic data charts 1954-2002 (last update October 13, 2002)]
[Archived reports (last update December 9, 2002)]

Recent activity

The geomagnetic field was quiet to unsettled on December 11. Solar wind speed ranged between 347 and 419 km/sec.

Solar flare activity was low. Solar flux was 152.3, the planetary A index was 6 (STAR Ap - based on the mean of three hour ap indices: 8.1).
Three hour interval K indices: 22122322 (planetary), 21223121 (Boulder).

The background x-ray flux is at the class C1 level.

At midnight there were 6 spotted regions on the visible disk, 2 of which have not yet been numbered. A total of 9 C class flares were recorded during the day.

Region 10209 rotated out of view at the southwest limb by noon.
Region 10212 decayed and was spotless after noon. 
Region 10213 reemerged with a few spots.
Region 10215 decayed quickly and could soon become spotless.
Region 10217 decayed and became spotless early in the day.
Region 10218 decayed slowly and quietly.
Region 10219 decayed and was spotless by noon.
Region 10220 decayed and lost nearly half of the penumbral area in the trailing spot section. The leading penumbra slowly increased its areal coverage. Flares: C1.6 at 01:13, C2.2 at 13:58, C7.1 at 14:10 and C2.3 at 19:55 UTC.
Region 10221 decayed and became spotless during early evening. Flare: C2.1 at 06:07 UTC.
New region 10222 emerged quickly in the southeast quadrant on December 10 and decayed quickly on December 11 becoming spotless by late evening.

Spotted regions not yet numbered by SEC:
[S51] A new region began rotating into view at the northeast limb late on December 11. Location at midnight: N25E82. This is possibly old region 10199.
[S52] A new region rotated into view at the southeast limb late on December 11. Location at midnight: S16E80. This could be old region 10198.

Coronal mass ejections (CMEs)

December 9-11: No obviously geoeffective CMEs noted. A couple of CMEs have been observed off of the east limb over the past couple of days and may have had their origin in the regions currently rotating into view.

Coronal holes

Coronal hole history (starting late October 2002)
Compare today's report with the situation one solar rotation ago: 29 days ago 28 days ago 24 days ago

A fairly small, decaying, recurrent coronal hole in the southern hemisphere was in a geoeffective position on December 10-11.

Processed SOHO EIT 284 image at 19:06 UTC on December 11. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 12-13. A weak coronal stream will likely begin on December 13 and could cause a few active intervals. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to good.

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.
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.

Active solar regions (Recent map)

Composite image based on a SOHO/MDI continuum image and overlaid by a coronal hole image. Region numbering has been included.

Data for all numbered solar regions according to the Solar Region Summary provided by SEC/NOAA. Comments are my own, as is the STAR spot count (spots observed at or just prior to midnight) and data for regions not numbered by SEC or where SEC has observed no spots.

Monthly solar cycle data

1) Running average based on the daily 20:00 UT observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official international sunspot number is typically 25-45% less.

This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources noted in solar links. Comments and suggestions are always welcome.