Solar Terrestrial Activity Report

Last update issued on February 13, 2003 at 04:00 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update February 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2002 (last update January 27, 2003)]
[Archived reports (last update February 10, 2003)]

Recent activity

The geomagnetic field was quiet to active on February 12. Solar wind speed ranged between 346 and 397 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 131.6. The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.1).
Three hour interval K indices: 22233433 (planetary), 12232323 (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 4 C class events was recorded during the day.

Region 10276 was quiet and stable.
Region 10277 decayed significantly and will likely become spotless today.
Region 10278 decayed slowly and quietly.
Region 10280 decayed slowly. Flares: C8.7/1F (with an associated weak type II radio sweep) at 01:51 and C2.9 at 16:12 UTC.
Region 10281 decayed slowly and quietly.
Region 10282 developed slowly and could produce further C class flares. Flares: C2.4 at 05:42 and C2.3 at 21:12 UTC.
Region 10283 decayed slowly and could soon become spotless.
Region 10285 decayed slightly and lost its trailing spot.

Coronal mass ejections (CMEs)

February 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

A trans equatorial coronal hole and a southern polar coronal hole extension will rotate into a geoeffective position on February 12-18. 

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

Forecast

The geomagnetic field is expected to be quiet to active on February 13-14. A coronal stream will likely reach Earth on February 15 and could cause unsettled to minor storm conditions until February 21, isolated major storm conditions are possible during the early phase. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor, propagation along north-south paths 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)

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.