Solar Terrestrial Activity Report

Last update issued on October 13, 2003 at 03:00 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update October 4, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update July 23, 2003)]
[Archived reports (last update October 7, 2003)]

Recent activity

The geomagnetic field was quiet to slightly unsettled on October 12. Solar wind speed ranged between 286 and 369 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 97.8. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 7.0).
Three hour interval K indices: 12132222 (planetary), 00113311 (Boulder).

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

At midnight there were 2 spotted regions on the visible disk. Solar flare activity was very low.

Region 10477 decayed slowly and quietly.
Region 10479 was quiet and stable.

Coronal mass ejections (CMEs)

October 10-12: No potentially 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 recurrent trans equatorial coronal hole (CH62) was in a geoeffective position on October 10. Another recurrent trans equatorial hole (CH63) will rotate into a geoeffective position on October 12-14. CH63 has become much smaller over the last rotation.

Processed SOHO/EIT 284 image at 01:06 UTC on October 12. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on October 13-14 due to a high speed stream from coronal hole CH62. A high speed stream from coronal hole CH63 will likely cause unsettled to major storm conditions on October 15-17.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is fair to good, excellent propagation was observed during the morning of October 12 and until 02 UTC on October 13. Propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: None early on. Numerous US stations noted until 0230 UTC, after then Radio Vibración (Venezuela) began to dominate].

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 NOAA/SEC. 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 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically 30-50% less.

This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.