Solar Terrestrial Activity Report

Last update December 11, 2002 at 03:50 UTC. Minor update posted at 11:01 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 10. Solar wind speed ranged between 392 and 502 km/sec.

Solar flare activity was moderate. Solar flux was 161.4, the planetary A index was 7 (STAR Ap - based on the mean of three hour ap indices: 8.4).
Three hour interval K indices: 22122322 (planetary), 22212213 (Boulder).

The background x-ray flux is at the class B8 level.

At midnight there were 9 spotted regions on the visible disk, 1 of which has not yet been numbered. A total of 10 C and 1 M class flares were recorded during the day. C2.1 flares at 11:02 and 17:22 UTC were optically unaccounted.

Region 10209 was quiet and stable and will rotate out of view today.
Region 10212 decayed further and was quiet. 
Region 10213 decayed into spotless plage.
Region 10215 decayed slowly and quietly.
Region 10216 decayed and was spotless by early evening.
Region 10217 decayed slowly and could soon become spotless.
Region 10218 was quiet and stable.
Region 10219 was quiet and stable.
Region 10220 developed slowly early in the day, slow decay was observed after the M flare. Another minor M class flare is possible. Flares: C5.5 at 01:32, C2.9 at 03:59, C2.8 at 04:08, C4.0 long duration event peaking at 07:22, M1.1 at 12:26, C1.3 at 14:48 and C2.6 at 19:36 UTC.
Region 10221 developed slowly and was quiet.

Spotted regions not yet numbered by SEC:
[S50] A new region emerged quickly in the southeast quadrant on December 10. Location at midnight: S07E09.

Comment added at 11:01 UTC on December 11: Observations today: Slow decay is occurring in the trailing spots of region 10220. Region S50 has decayed fairly quickly today and could become spotless before midnight. Several of the remaining spotted regions are decaying as well with region 10217 currently spotless. One new region is visible. It is located in the southwest quadrant, currently near S07W40. Otherwise the geomagnetic field has been quiet during the first half of the day.

Coronal mass ejections (CMEs)

December 8-10: No obviously geoeffective CMEs noted.

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 27 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 10. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 11-13. A weak coronal stream will likely begin on December 13. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair.

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.