Solar Terrestrial Activity Report

Last update issued on January 28, 2003 at 04:05 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 January 27, 2003)]
[Archived reports (last update January 27, 2003)]

Recent activity

The geomagnetic field was quiet to unsettled on January 27. Solar wind speed ranged between 446 and 641 km/sec. A coronal stream ended early in the day. An apparent solar wind shock was observed at approximately 16:30 UTC at SOHO.

Solar flux measured at 20h UTC on 2.8 GHz was 121.3. The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 9.5).
Three hour interval K indices: 32112323 (planetary), 32112333 (Boulder).

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

At midnight there were 9 spotted regions on the visible disk, 1 of which has not yet been numbered by SEC/NOAA. Solar flare activity was low. Only 1 C class event was recorded. This was a C2.4 long duration event peaking at 22:19 UTC. Its origin was a filament eruption in the southwest quadrant located between regions 10267, 10266 and 10271. A type II radio sweep was associated with this event. A fairly narrow CME was observed below the south pole and the southeast and southwest limbs during the hours after the event.

Region 10266 decayed slowly and lost its easternmost trailing spots as well as penumbral area in the two largest penumbrae.
Region 10267 decayed further and lost all trailing spots.
Region 10268 decayed and lost most of its penumbral area.
Region 10269 decayed and will likely lose its trailing spots today..
Region 10270 was mostly unchanged and quiet.
Region 10271 decayed slowly and quietly.
Region 10272 decayed slowly and quietly.
New region 10273 emerged in the northwest quadrant on January 26 and was numbered the next day. The region developed moderately quickly during the day.

Spotted regions not yet numbered by SEC/NOAA:
[S82] A new region rotated into view at the southeast limb late in the day. Location at midnight: S09E80.

Coronal mass ejections (CMEs)

January 25-27: 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 small trans equatorial coronal hole was in a geoeffective position on January 26-27. An extension of the northern polar coronal hole will probably become geoeffective on January 30.

Processed SOHO EIT 284 image at 01:06 UTC on January 28. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 28 and most of January 29. Quiet to active is likely from late on January 29 until January 31 due to a coronal stream. 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. 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.