Solar Terrestrial Activity Report

Last update December 30, 2002 at 04:00 UTC. Minor update posted at 16:55 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 30, 2002)]

Recent activity

The geomagnetic field was quiet to unsettled on December 29. Solar wind speed ranged between 509 and 719 km/sec, decreasing all day.

Solar flux was 114.8 (adjusted to 1 AU, this is the lowest solar flux level since September 9, 1999).
The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 14.1).
Three hour interval K indices: 32333333 (planetary), 31333332 (Boulder).

The background x-ray flux is at the class B1-B2 level.

At midnight there were 4 spotted regions on the visible disk, 1 of which has not yet been numbered. Solar flare activity was very low.

Region 10234 was quiet and stable.
Region 10235 reemerged with a few spots. [Correction added at 16:55 UTC, spotless region 10236 was removed]
New region 10239 emerged in the southeast quadrant on December 28 and was numbered the next day. The region developed slowly and may be capable of C class flaring.

Spotted regions not yet numbered by SEC:
[S63] A new region emerged in the southwest quadrant on December 29. Location at midnight: S15W15.

Coronal mass ejections (CMEs)

December 27-29: No obviously geoeffective CMEs observed.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent trans equatorial coronal hole will rotate into a geoeffective position on January 1.

Processed SOHO EIT 284 image at 01:06 UTC on December 30. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on December 30 and quiet to unsettled on December 31 - January 2. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is 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 and a coronal emission intensity image. Region numbering has been included. Compare to the previous day's image. 

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 inside a few hours before 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.