Solar Terrestrial Activity Report

Last major update issued on January 18, 2006 at 04:10 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 8, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 8, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 8, 2006)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update January 8, 2006)]

Recent activity

The geomagnetic field was quiet to unsettled on January 17. Solar wind speed ranged between 395 and 515 (all day average 436) km/sec under the decreasing influence of a stream from CH205.

Solar flux measured at 20h UTC on 2.8 GHz was 82.5. The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.5).
Three hour interval K indices: 23222211 (planetary), 23232212 (Boulder).

The background x-ray flux is at the class A2 level.

At midnight there were two spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10846 decayed further and could soon become spotless
Region 10847 decayed slowly and quietly.

Coronal mass ejections (CMEs)

January 15-17: No obviously fully or partly Earth directed CMEs were 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 (CH206) will likely rotate to an Earth facing position late on January 21-22.

Processed SOHO/EIT 284 image at 01:06 UTC on January 18. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be mostly quiet on January 18-22 and become unsettled to minor storm on January 23-24 due to effects from CH206.

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) Effects from a CME are likely to be observed at 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.

Propagation

/* No monitoring on January 18 */ Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is excellent. Propagation on long distance northeast-southwest paths is very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: WLAM Lewiston ME. On other frequencies there were many stations from mostly the eastern half of North America. As an example 870 kHz had WWL New Orleans as a clear dominant. During WWL fades it was possible to hear two other stations, one with a news talk format (possibly Ithaca, NY station) and another with oldies. On 1000 kHz KOMO Seattle WA had, at times, a strong signal.

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% lower.

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