Solar Terrestrial Activity Report

Last major update issued on January 30, 2006 at 04:30 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 inactive to very quiet on January 29. Solar wind speed ranged between 347 and 483 (all day average 524) km/sec, slowly decreasing all day.

Solar flux measured at 20h UTC on 2.8 GHz was 79.5. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.8).
Three hour interval K indices: 11101100 (planetary), 12110110 (Boulder).

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

At midnight the visible solar disk was spotless. The solar flare activity level was very low. No C class events were recorded during the day.

Coronal mass ejections (CMEs)

January 27-29: No obviously fully or partly Earth directed CMEs were observed. Images for January 29 were unavailable when I wrote this.

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 small southern hemisphere coronal hole (CH207) was in an Earth facing position on January 28-29. A poorly defined coronal hole (CH208) in the northern hemisphere could rotate into an Earth facing position on January 30.

Processed SOHO/EIT 284 image at 19:06 UTC on January 29. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet on January 30. Weak effects from CH207 and CH208 are possible on January 31-Februay 2.

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

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela). Propagation was similar to the previous night with the best signals coming from stations on Nova Scotia and in or close to New York.

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.