Solar Terrestrial Activity Report

Last update January 17, 2003 at 04:30 UTC. The next update will be issued early on January 20 as I will be away during the weekend.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 1, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 1, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update January 1, 2003)]
[Historical solar and geomagnetic data charts 1954-2002 (last update October 13, 2002)]
[Archived reports (last update January 13, 2003)]

Recent activity

The geomagnetic field was quiet to unsettled on January 16. Solar wind speed ranged between 307 and 394 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 144.6. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 8.6).
Three hour interval K indices: 22123322 (planetary), 21122212 (Boulder).

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

At midnight there were 8 spotted regions on the visible disk. Solar flare activity was low. A total of 3 C class events were recorded during the day.

Region 10247 decayed further and could become spotless before rotating over the southwest limb on January 18.
Region 10250 decayed slowly and quietly.
Region 10251 decayed further and will likely lose all remaining trailing spots today. Flare: C5.3/1N at 01:08 UTC.
Region 10254 decayed slowly and quietly.

Region 10255 was split off from region 10251 on January 12 by SEC/NOAA. This split was doubtful even then and it is currently obvious that it was a premature decision.
Region 10256 was split off from region 10254 on January 12 by SEC/NOAA. Regions 10254 and 10256 make up one bipolar region with the negative polarity area in the west and the positive area to the east. It remains to be seen if SEC will merge the "two" regions again.

Region 10257 decayed and could lose its remaining spot early on January 17.
Region 10258 was mostly unchanged. Flares: C1.8/1F at 04:50 and a long duration C2.0 event peaking at 12:18 UTC.
Region 10259 developed slowly adding several leading spots.
Region 10260 was quiet and stable.

Coronal mass ejections (CMEs)

January 14-16: 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 large and wide trans equatorial extension of the southern polar coronal hole in the will rotate into a geoeffective position on January 19-23.

Processed SOHO EIT 284 image at 19:06 UTC on January 16. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be mostly quiet on January 17-20 and unsettled to minor storm on January 21-26 due to a coronal stream. 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. 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.