Solar Terrestrial Activity Report

Last major update issued on January 3, 2004 at 03:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 2, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update December 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update October 15, 2003)]
[Archived reports (last update December 30, 2003)]

Recent activity

The geomagnetic field was quiet to active on January 2. Solar wind speed ranged between 442 and 544 km/sec, slowly decreasing most of the day, some increase in wind speed was noted late in the day..

Solar flux measured at 20h UTC on 2.8 GHz was 116.5. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.5).
Three hour interval K indices: 32223433 (planetary), 33223322 (Boulder).

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

At midnight there were 3 spotted regions on the visible disk. Solar flare activity was low. A total of 4 C class events were recorded during the day.

Region 10534 decayed slowly and elongated. Flare: C2.8 at 02:58 UTC.
Region 10535 developed slowly and quietly.
Region 10536 was mostly unchanged and could produce an M class flare. Flares: C1.0 at 01:57, C1.2 at 13:59 and C1.2 at 17:00 UTC.

Coronal mass ejections (CMEs)

December 31 - January 2: No partly or fully earth directed CMEs observed from the limited data set currently available.

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 large, recurrent trans equatorial coronal hole (CH74) will be in a geoeffective position January 1-7.

Processed SOHO/EIT 284 image at 19:06 UTC on December 26. 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 3-10 with occasional major storm intervals due to a high speed stream from coronal hole CH74.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along long distance north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay with occasional interference from Radio Rafaela (Argentina) and Rádio Papacaça AM].

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.