Solar Terrestrial Activity Report

Last update December 9, 2002 at 04:15 UTC. Minor update posted at 11:23 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 active on December 8. Solar wind speed ranged between 537 and 707 km/sec under the influence of a coronal stream.

Solar flare activity was low. Solar flux was 154.4, the planetary A index was 12 (STAR Ap - based on the mean of three hour ap indices: 12.3).
Three hour interval K indices: 24223433 (planetary), 23223322 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight there were 13 spotted regions on the visible disk, 3 of which have not yet been numbered. A total of 3 C class flares were recorded during the day.

Region 10205 reemerged quickly with several spots. C flares are possible. The region will rotate over the northwest limb today.
Region 10207 was quiet and stable and is rotating over the southwest limb.
Region 10208 decayed and was spotless by noon 
Region 10209 was quiet and stable..
Region 10212 developed slowly north of the main penumbra, otherwise minor decay was observed. 
Region 10213 decayed further and could become spotless today.
Region 10214 decayed a lot in the trailing spot section. Flare: C2.5 at 08:25 UTC. 
Region 10215 changed appearance as the main penumbra split into two penumbrae. A few trailing spots were visible during the day.
New region 10216 emerged in the southwest quadrant on Dec.7 and was numbered on Dec.8. Only slow development was observed during the day.
New region 10217 emerged at the northeast limb on Dec.7 and was numbered on Dec.8 and developed slowly.
New region 10218 rotated into view at the southeast limb on Dec.7 and was numbered on Dec.8. The region decayed slowly during the day. Flare: C2.5 at 23:26 UTC. 

Spotted regions not yet numbered by SEC:
[S43] A new region emerged in the southeast quadrant on December 6. The region decayed slowly on Dec.7 and had only a single small spot left by the end of the day. Slow development was observed on Dec.8. Location at midnight: S08W08.
[S47] A new region emerged very quickly on Dec.8 in the southeast quadrant and could soon become capable of producing M class flares. There appears to be a magnetic delta in the leading penumbra. Location at midnight: S12E60.
[S48] A new region rotated into view at the northeast limb on Dec.8. Location at midnight: N23E76.

Comment added at 11:23 UTC on December 9: Region S47 has continued to develop quickly during the first half of the day. The region is currently the largest on the visible disk and has a magnetic delta structure. New spots have emerged in the eastern and southeastern part of the region. The possibility of an M class flare is quickly increasing. Region S43 is developing slowly and has added a few small spots while the main penumbra has increased its area. C class flares could become possible soon.
The geomagnetic field has been quiet to unsettled so far today.

Coronal mass ejections (CMEs)

December 6-8: 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 27 days ago 26 days ago

A small, decaying, recurrent coronal hole in the southern hemisphere will rotate into a geoeffective position on December 10.

Processed SOHO EIT 284 image at 01:06 UTC on December 9. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 9-13. 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 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.