Solar Terrestrial Activity Report

Last major update issued on January 27, 2005 at 04:50 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 2, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 2, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 2, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update November 8, 2004)]
[Archived reports (last update January 19, 2005)]

Recent activity

The geomagnetic field was inactive to very quiet on January 26. Solar wind speed ranged between 348 and 430 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 89.3. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.6).
Three hour interval K indices: 11011111 (planetary), 11011220 (Boulder).

The background x-ray flux is at the class A6 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Coronal mass ejections (CMEs)

January 24-26: No obvious 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 coronal hole (CH141) in the southern hemisphere was in a geoeffective position on January 25-26. A recurrent coronal hole in the northern hemisphere (CH142) will be in a geoeffective position on January 27-28.

Processed SOHO/EIT 284 image at 13:06 UTC on January 26. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet on January 27 and most of January 28. On January 28-29 a high speed stream from coronal hole CH141 is likely to cause unsettled to active conditions while effects from coronal hole CH142 could extend these conditions until February 1.

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is variable and ranged between poor and fair during the listening sessions. Propagation along long distance north-south paths is very poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: CPN Radio (Perú) was observed before midnight UTC, a very unusual occurrence. At the time a few other frequencies had stations from Perú as well, and no other trans Atlantic signals were heard. Later on propagation towards North America was periodically fair with stations noted on quite a few frequencies, however, it was heard to discern a pattern as the stations usually dominant on a frequency in some cases were not heard at all. Greenland on 650 kHz had a fairly strong signal most of the night.

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 some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.