Solar Terrestrial Activity Report

Last update issued on February 17, 2003 at 02:30 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 16. Solar wind speed ranged between 547 and 680 km/sec under the influence of a coronal stream.

Solar flux measured at 20h UTC on 2.8 GHz was 118.5. 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: 23434334 (planetary), 22433323 (Boulder).

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

At midnight there were 2 spotted regions on the visible disk. Solar flare activity was low. A total of 3 C class events was recorded during the day, this includes two events with an origin behind the southwest limb: C1.0 at 01:45 and C1.1 at 03:25 UTC. A long duration C1.4 event peaked at 22:42 UTC, this event had its source behind the northwest limb.

Region 10285 reemerged early in the day, then decayed slowly and had only a tiny spot left by the end of the day. The region will likely become spotless again today.
Region 10288 developed slowly and quietly. C class flares are possible.

Coronal mass ejections (CMEs)

February 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 trans equatorial coronal hole and a southern polar coronal hole extension was in a geoeffective position on February 12-18. 

Processed SOHO EIT 284 image at 01:06 UTC on February 17. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to active with occasional minor storm intervals until February 21. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor to very poor, propagation along north-south paths 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)

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.