Solar Terrestrial Activity Report

Last major update issued on January 16, 2004 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 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 9, 2004)]

Recent activity

The geomagnetic field was quiet to active on January 15. Solar wind speed ranged between 418 and 614 km/sec. A disturbance began after noon with solar wind speed increasing and the interplanetary magnetic field swinging moderately southwards at times.

Solar flux measured at 20h UTC on 2.8 GHz was 119.1. The planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 16.8).
Three hour interval K indices: 23224443 (planetary), 23214433 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 4 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded during the day.

Region 10537 was quiet and decayed further, mainly in the northern part of the single penumbra. A minor M flare remains a possibility.
Region 10540 developed in the trailing and intermediate spot section. A negative polarity area emerged at the southwestern edge of the trailing positive polarity area. Several spots emerged in this area and there is now a weak magnetic delta structure there. A minor M class flare is possible. Flares: C3.2/1F at 06:32 and C1.2 at 23:04 UTC.
New region 10541 emerged on January 13 and was numbered two days later by SEC. The region developed early on January 15, slow decay was observed late in the day.

Spotted regions not numbered by NOAA/SEC:
[S332] This region began rotated into view at the northeast limb late on January 14 and developed slowly on January 15. Location at midnight: N11E67.

There is an unusually large and dense tilted J-shaped filament in the northeast quadrant, it is trailing coronal hole CH76 and has nearly the same shape. An eruption of this filament will cause a large CME.

Coronal mass ejections (CMEs)

January 13-15: No partly or fully earth directed 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 (CH76) will rotate into a geoeffective position on January 13-16, the coronal hole is well defined in the northern and central parts.

Processed SOHO/EIT 284 image at 01:06 UTC on January 16. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on January 16 until January 19 due to a high speed stream from coronal hole CH76.

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 very good to excellent. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay with a weak signal on the southwesterly antenna, Radio Vibración (Venezuela) poorly on the northwesterly EWE. Even heard a surprising Radio Cuzco ID, but this station is not listed on this frequency. Propagation towards southern and central Brazil was superb, i.e. Super AM 1440 in Rio de Janeiro had the best (local like) signal I've ever heard from that country. Another example is 1150 kHz which at one time had 3 different stations from Brazil competing. Switching in the northwesterly EWE just before 04h UTC was quite interesting with carriers noted on several unexpected frequencies, audio on 970 kHz had a US station with commercials - no east coast stations noted at this time!].

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.