Solar Terrestrial Activity Report

Last update December 15, 2002 at 04:10 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 14. Solar wind speed ranged between 345 and 561 km/sec under the influence of a weak coronal stream.

Solar flare activity was low. Solar flux was 185.9, the planetary A index was 11 (STAR Ap - based on the mean of three hour ap indices: 11.8).
Three hour interval K indices: 22223333 (planetary), 22222333 (Boulder).

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

At midnight there were 10 spotted regions on the visible disk, 1 of which has not yet been numbered. A total of 12 C class flares were recorded during the day.

Region 10218 decayed slowly and quietly.
Region 10220 decayed further and was mostly quiet.
Region 10223 was mostly unchanged and may be capable of producing a minor M class flare.
Region 10224 developed many new spots in the trailing spot section and could produce an M class flare. Flare:  C1.9 at 18:20 UTC.
Region 10225 rotated partly into view at the northeast limb on December 12 and was numbered on Dec.13.
Region 10226 developed quickly and could produce an M class flare. Flares: C1.9 at 04:38, C3.9/1F at 08:38, C2.0 at 12:01, C2.0 at 12:54 and C2.1 at 20:35 UTC.
Region 10227 developed slowly and quietly.
New region 10228 rotated into view at the southeast limb on December 13 and was numbered one day later. This unimpressive region could soon become spotless.
New region 10229 rotated into view at the northeast limb on Dec.13 and was numbered on Dec.14. The region developed moderately quickly and has M class flare potential. Flares: C1.1 at 06:47, C3.1 long duration event peaking at 14:24 and C2.9 at 15:04 UTC.

Spotted regions not yet numbered by SEC:
[S57] A new region emerged southwest of region 10218 on December 14. Location at midnight: S21W15.

Coronal mass ejections (CMEs)

December 12-14: 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: 27 days ago 26 days ago 25 days ago

A trans equatorial, recurrent extension of the southern polar coronal hole will rotate into a geoeffective position on December 15-16.

Processed SOHO EIT 284 image at 19:06 UTC on December 14. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be mostly quiet to unsettled on December 15-16. A significantly stronger coronal stream is likely to arrive on December 17 and cause unsettled to minor or event major storm conditions. 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.