Solar Terrestrial Activity Report

Last update issued on February 11, 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 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 unsettled to active on February 10. Solar wind speed ranged between 411 and 463 km/sec under the influence of a coronal stream.

Solar flux measured at 20h UTC on 2.8 GHz was 136.2. The planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 16.8).
Three hour interval K indices: 34433333 (planetary), 34432233 (Boulder).

The background x-ray flux is at the class B3 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. A total of 2 C class events were recorded during the day, including a long duration C1.1 event peaking at 22:42 UTC with its origin at the southwest limb.

Region 10276 decayed further losing both leading and trailing spots.
Region 10277 developed slowly and was mostly quiet. Flare: C1.2 at 02:30 UTC.
Region 10278 decayed slowly and quietly.
Region 10280 developed slowly and quietly.
Region 10281 was quiet and stable.
Region 10282 did not change much and was quiet.
Region 10283 decayed slowly and quietly.
Region 10285 split off a small trailing penumbra.

Spotted regions not yet numbered by SEC/NOAA:
[S90] A new region emerged in the southeast quadrant on February and has since been visible some days. Location at midnight: S13W06.

Coronal mass ejections (CMEs)

February 8-10: 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 will rotate into a geoeffective position on February 13-15. 

Processed SOHO EIT 284 image at 01:06 UTC on February 11. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on February 10-14. Another coronal stream will likely reach Earth on February 15 or 16 and could cause unsettled to minor storm conditions. 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.