Solar Terrestrial Activity Report

Last major update issued on January 8, 2004 at 05:10 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 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 October 15, 2003)]
[Archived reports (last update January 1, 2004)]

Recent activity

The geomagnetic field was unsettled to minor storm on January 7 and became quiet early on January 8. Solar wind speed ranged between 559 and 890 km/sec, slowly decreasing after noon as the effects from the CME (which arrived during the evening of January 6) diminished.

Solar flux measured at 20h UTC on 2.8 GHz was 118.8. The planetary A index was 32 (STAR Ap - based on the mean of three hour interval ap indices: 34.4).
Three hour interval K indices: 34555543 (planetary), 34664533 (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 high. A total of 2 C and 2 M class events was recorded during the day.

Region 10536 decayed slowly with most of the decay occurring in the eastern part of the region. There is a significant magnetic delta structure in the southeastern part of the huge main penumbra. A small delta is located further north while another delta has formed in a penumbra in the southwestern part of the region. A major flare remains a possibility. Flares: C2.9 at 08:45 and C1.0 at 14:35 UTC.
Region 10537 developed adding new penumbrae in the north and in the southwest. There is a fairly strong magnetic delta in the central part of the region where the opposite polarity umbrae are narrowly separated. As long as the current configuration exists there will be a good chance of impulsive major flares. Flares: M4.5 at 04:10 and an impulsive major M8.3 flare at 10:27 UTC. Both events were associated with weak type II radio sweeps and a CME.
This region was the source of an M1.3 flare at 05:07 UTC on January 8.
New region 10538 emerged in the northeast quadrant early in the day, then began to decay and could soon become spotless.
New region 10539 emerged in the northeast quadrant early in the day.

Coronal mass ejections (CMEs)

January 7: Fast and wide full halo CMEs were observed in LASCO C3 images after the M flares in region 10537. Most of the ejected material was observed off of the east limbs with the leading edge of the first CME having a speed in excess of 1700 km/sec. Flank CME impacts are likely on January 9.

A large filament to the west and southwest of region 10536 erupted beginning just before 18h UTC. At least a partial halo CME was observed in LASCO images with ejected material observed off of the south and west limb.

January 6: 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 (CH74) was in a geoeffective position on January 1-6. The southernmost extension of a coronal hole (CH75) in the northern hemisphere could be in a geoeffective position on January 9.

Processed SOHO/EIT 284 image at 19:06 UTC on January 7. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on January 8 and most of January 9. Flank impacts from CMEs originating in region 10537 on January 7 are possible during the latter half of January 9 and could cause unsettled to minor storm conditions. Active to minor storm conditions are possible on January 10 when a CME observed during the evening of January 7 is likely to reach the Earth. A high speed stream from coronal hole CH75 may cause unsettled to active conditions on January 12.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to very poor. Propagation along long distance north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Rafaela (Argentina) on the southwesterly longwire, Radio Vibración (Venezuela) on the EWEs directed west and northwest. WWZN Boston on 1510 kHz was noted again and there were lots of carriers on frequencies above 1350 kHz].

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.