Solar Terrestrial Activity Report

Last update January 13, 2003 at 03:50 UTC. Minor update posted at 17:04 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
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[Solar cycles 21-23 (last update January 1, 2003)]
[Solar cycles 1-20]
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[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update January 1, 2003)]
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[Archived reports (last update January 13, 2003)]

Recent activity

The geomagnetic field was quiet to unsettled on January 12. Solar wind speed ranged between 358 and 463 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 173.4. The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.4).
Three hour interval K indices: 22323332 (planetary), 22322332 (Boulder).

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

At midnight there were 7 spotted regions on the visible disk, 1 of which has not yet been numbered. Solar flare activity was low. A total of 8 C class events were recorded during the day. Optically uncorrelated flares were recorded at 06:55 (C1.5), 09:15 (C2.0) and 23:47 (C1.5).

Region 10242 decayed significantly and will rotate over the southwest limb today. Flares: C2.2 at 07:03, C3.7 long duration event peaking at 07:42, C6.1 at 14:25 and C1.2 at 18:10 UTC.
Region 10247 developed many small spots in the trailing spot section. At the same time all larger spots lost penumbral area. The region is currently simply structured and further decay is likely. Flare: C2.1 at 00:42 UTC.
Region 10249 decayed slowly and quietly.
Region 10250 was quiet and unchanged.
Region 10251 was mostly unchanged and quiet. An M class flare is possible.
Region 10254 decayed slowly and quietly.

New region 10255 was split off from region 10251 by SEC/NOAA. This split appears to be somewhat artificial, and, based on white light and magnetogram analysis, should have been avoided.
New region 10256 was split off from region 10254 by SEC/NOAA. To me this appears to be an extremely doubtful decision. Regions 10254 and 10256 basically make up one bipolar region with the negative polarity area in the west and the main positive area to the east.

Spotted regions not yet numbered by SEC/NOAA:
[S72] A new region emerged late on January 10 in the northwest quadrant just southeast of region 10253. The region had only a couple of spots at midnight and developed slowly early on January 11. Slow decay was observed later in the day and on January 12. The region will likely become spotless on Jan.13 . Location at midnight: N07W60.

Comment added at 17:04 UTC on January 13: With little activity in the numbered regions, it has been more interesting observing new regions appear. Three new regions are visible. One is a small bipolar region southwest of region 10247, this was a BXO region with 2 spots a few hours ago. A new region emerged quickly in the northeast quadrant and currently has 5 spots in a DAO configuration. The most interesting region is rotating into view at the northeast limb. The prominence above the region is quite a sight in recent images, see this SOHO/EIT 304 image at 13:19 UTC.

Coronal mass ejections (CMEs)

January 10-12: 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

No obvious coronal holes are currently approaching geoeffective positions.

Processed SOHO EIT 284 image at 01:06 UTC on January 13. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 13-16. 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. 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. All time references are to the UTC day. Comments and suggestions are always welcome.