Solar Terrestrial Activity Report

Last major update issued on January 9, 2004 at 04:15 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 quiet to unsettled on January 8. Solar wind speed ranged between 481 and 683 km/sec, generally decreasing all day.

Solar flux measured at 20h UTC on 2.8 GHz was 120.1. The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 10.4).
Three hour interval K indices: 21133323 (planetary), 10023223 (Boulder).

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

At midnight there were 2 spotted regions on the visible disk. Solar flare activity was moderate. A total of 3 C and 1 M class events was recorded during the day.

Region 10536 decayed slowly. 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.
Region 10537 developed slowly in the main penumbral area while slow decay was observed in the northernmost spots. 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: C1.3 at 04:16, M1.3/1N at 05:07, C1.3 at 16:41 and C1.1 at 17:35 UTC. This region has produced 2 M flares early on January 9: M1.1 at 01:22 and M3.2 at 01:44 UTC.

Coronal mass ejections (CMEs)

January 7: A fast and wide halo CME was observed in LASCO C3 images after the M8 flare in region 10537. Most of the ejected material was observed off of the east limb with the leading edge of the second CME having a speed in excess of 1700 km/sec.

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

January 6 and 8: 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

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 01:06 UTC on January 9. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active most of January 9. A flank impact from a CME originating in region 10537 on January 7 is possible during the latter half of January 9 or early on January 10 and could cause brief unsettled to minor storm conditions. Active to minor storm conditions are possible during the latter half of January 10 and early on January 11 in response to the arrival a partial halo CME observed during the evening of January 7. 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 fair to 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) and WLAM Lewsiton ME on the EWEs directed west and northwest. Quite a few US and Canadian east coast stations were noted on other freqeuncies].

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.