Solar Terrestrial Activity Report

Last update issued on January 25, 2003 at 03:55 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update 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 20, 2003)]

Recent activity

The geomagnetic field was quiet to active on January 24. Solar wind speed ranged between 593 and 810 km/sec under the influence of a strong coronal stream. The maximum observed solar wind speed on Jan.24 is the highest recorded during this solar cycle for a coronal hole based disturbance.

Solar flux measured at 20h UTC on 2.8 GHz was 129.8. The planetary A index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 15.9).
Three hour interval K indices: 42233433 (planetary), 42333333 (Boulder).

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

At midnight there were 6 spotted regions on the visible disk. Solar flare activity was moderate. A total of 3 C and 1 M class events were recorded.

Region 10258 rotated quietly to the northwest limb.
Region 10260 decayed and became spotless after noon.
Region 10263 did not change much and remains capable of producing an M class event while at the southwest limb today and tomorrow.
Region 10266 decayed in the trailing spot section while the leader spots increased their penumbral area. Flares: M1.9/1N (with associated strong type II and IV radio sweeps) at 03:27, C2.8 at 05:09, C5.6/1F at 15:50 and C1.3 at 22:14 UTC.
Region 10267 developed slowly in the trailing spot section and was otherwise unchanged and quiet.
Region 10268 developed slowly and still has a magnetic delta structure. There are signs that the trailing positive polarity spots are splitting off from the main penumbra. If that development continues the region will lose the magnetic delta. Minor M class flares are possible from this reversed polarity region.
Region 10269 was quiet and stable.

Coronal mass ejections (CMEs)

January 22-23: No obviously geoeffective CMEs observed.

January 24: A weak partial halo CME was observed in LASCO C2 images early in the day and appears to have been associated with the M1.9 event in region 10266 at 03:27 UTC. The CME could be geoeffective.

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 small trans equatorial coronal hole will likely rotate into a geoeffective position on January 27-28. Another coronal hole in the northern hemisphere will probably become geoeffective on January 30.

Processed SOHO EIT 284 image at 19:06 UTC on January 24. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active until January 27 due to a coronal stream. Quiet to unsettled is expected on January 28-29. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor to very 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. 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.