Solar Terrestrial Activity Report

Last major update issued on January 26, 2004 at 08:30 UTC. Added region S335 data at 10:02 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 4, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 4, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 4, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16, 2004)]
[Archived reports (last update January 19, 2004)]

Recent activity

The geomagnetic field was unsettled to minor storm on January 25. Solar wind speed ranged between 449 and 588. A disturbance was in progress all day.

Solar flux measured at 20h UTC on 2.8 GHz was 102.3. The planetary A index was 33 (STAR Ap - based on the mean of three hour interval ap indices: 33.9).
Three hour interval K indices: 55544433 (planetary), 44543333 (Boulder).

The background x-ray flux is at the class B1-B2 level.

At midnight there were 2 spotted regions on the visible disk. Solar flare activity was low. A total of 1 C class event was recorded during the day.

Region 10543 decayed slowly and will soon rotate over the southwest limb. Flare: C6.3 at 22:41 UTC.

Spotted regions not numbered by NOAA/SEC:
[S335] This region emerged in the southeast quadrant on January 25. Location at midnight: S19E33.

Coronal mass ejections (CMEs)

January 23-25: No partly or fully earth directed CME 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 (CH77) was in a geoeffective position on January 24-25. A recurrent coronal hole in the northern hemisphere will rotate into a geoeffective position on January 28-31.

Processed SOHO/EIT 284 image at 01:07 UTC on January 26. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 26-27 and unsettled to active on January 28 due to a high speed stream from coronal hole CH77.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along long distance north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. No monitoring today as I needed sleep after a long journey yesterday].

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. When the high speed stream has arrived the color changes to green.
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. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.

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.