Solar Terrestrial Activity Report

Last update issued on January 22, 2003 at 03:50 UTC. Minor update posted at 11:09 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 unsettled to active on January 21. Solar wind speed ranged between 562 and 717 km/sec under the influence of a strong coronal stream.

Solar flux measured at 20h UTC on 2.8 GHz was 133.6. The planetary A index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 18.0).
Three hour interval K indices: 33343333 (planetary), 33443323 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight there were 10 spotted regions on the visible disk, 1 of which has not yet been numbered by SEC/NOAA. Solar flare activity was moderate. A total of 7 C and 1 M class events were recorded. A long duration C2.9 event peaking at 08:22 likely had its origin in region 10257 at the northwest limb.

Region 10254 decayed slowly and will rotate over the southwest limb today.
Region 10258 was quiet and unchanged.
Region 10259 decayed slowly and lost the leader spots. Flare: C2.0 at 01:34 UTC.
Region 10260 was basically unchanged and could produce further C class flares. Flares: C8.1 at 02:28 (an event occurred simultaneously in region 10267 and it is difficult to be certain which region was the actual source of the C8 event), C4.1 (associated with a weak type II radio sweep) at 05:57, C3.0 at 13:10 and C2.3 at 21:40 UTC.
Region 10263 reemerged with a single small spot.
Region 10266 developed slowly. The positive and negative polarity areas have drifted slowly apart and further development is unlikely unless new flux emerges.
Region 10267 developed slowly and could produce C class flares. Flare: C1.8 at 09:27 UTC.
New region 10268 emerged in the northeast quadrant.
New region 10269 rotated into view at the southeast limb. This is a fairly small region, however, if the current magnetic delta structure persists, further M class flares will be possible. Flare: M1.9 long duration event peaking at 15:26 UTC.

Spotted regions not yet numbered by SEC/NOAA:
[S79] A new region emerged very quickly in the southwest quadrant a few degrees west of region 10263. There is currently a magnetic delta structure in the largest penumbra and C or even minor M class flares are possible. Location at midnight. S14W43.

Comment added at 11:09 UTC on January 22: Some observations during the first half of the day: Region S79 has decayed somewhat and lost its magnetic delta as the main penumbra split into smaller penumbrae. Region 10259 appears to have become spotless. A new region has emerged just north northeast of region 10258. An M1.2/1F flare with an origin in region 10260 was recorded at 04:44 UTC. No LASCO images covering the hours after the event are currently available.

Coronal mass ejections (CMEs)

January 19: No obviously geoeffective CMEs observed.

January 20: A filament eruption in the northeast quadrant began at approximately 19h UTC with its southwesternmost extension reaching nearly to region 10260. A slowly expanding, bright CME was observed over the northeast limb as early as 19:42 UTC in LASCO C3 images. Early on January 21 this CME became a partial halo CME as it extended south of the equator at the east limb and into the northwest limb. The CME is probably not geoeffective.

January 21: A large CME was observed off of the southeast limb after the M1.9 event in region 10269. The CME is unlikely to 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 huge trans equatorial extension of the southern polar coronal hole was in a geoeffective position on January 16-23.

Processed SOHO EIT 284 image at 01:06 UTC on January 22. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm until January 26 due to a coronal stream. 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.