Solar Terrestrial Activity Report

Last update December 7, 2002 at 04:20 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 1, 2002)]

Recent activity

The geomagnetic field was quiet to unsettled on December 6. Solar wind speed ranged between 351 and 446 km/sec. A fairly weak coronal stream began to dominate the solar wind after 15h UTC.

Solar flare activity was low. Solar flux was 148.2, the planetary A index was 10 (STAR Ap - based on the mean of three hour ap indices: 10.1).
Three hour interval K indices: 22223333 (planetary), 12221322 (Boulder).

The background x-ray flux is at the class B3-4 level.

At midnight there were 8 spotted regions on the visible disk, 1 of which has not yet been numbered. A total of 2 C class flares were recorded during the day.

Region 10207 decayed further and lost all trailing spots.
Region 10208 decayed quickly losing many spots and most of its penumbral area. 
Region 10209 redeveloped a few trailing spots, the leading penumbra was unchanged.
Region 10212 was mostly unchanged and quiet. Flare: C1.7 at 10:46 UTC. 
Region 10213 did not change much and remained quiet.
Region 10214 developed further early in the day. Some decay was observed late in the day. Flare: C2.1 at 08:56 UTC. 
Region 10215 was quiet and stable.

Spotted regions not yet numbered by SEC:
[S43] A new region emerged in the southeast quadrant on December 6. Location at midnight: S08E16.

Coronal mass ejections (CMEs)

December 4-6: 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: -1 day 27 days ago +2 days

The southernmost part of an extension of the northern polar coronal hole may have been in a geoeffective position on December 4. A slowly developing trans equatorial coronal hole was in a geoeffective position on December 4.

Processed SOHO EIT 284 image at 19:06 UTC on December 6. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on December 7-8 and quiet to unsettled on December 9-10. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is fair to poor.

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.