Solar Terrestrial Activity Report

Last major update issued on February 8, 2004 at 04:20 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update February 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update February 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16, 2004)]
[Archived reports (last update February 3, 2004)]

Recent activity

The geomagnetic field was very quiet to unsettled on February 7. Solar wind speed ranged between 418 and 554, gradually decreasing al day. 

Solar flux measured at 20h UTC on 2.8 GHz was 111.1. The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.1).
Three hour interval K indices: 22333320 (planetary), 23323221 (Boulder).

The background x-ray flux is at the class B2-B3 level.

At midnight there were 3 spotted regions on the visible disk. Solar flare activity was low. A total of 1 C class event was recorded during the day.

Region 10549 developed early in the day, then began to decay. At the current rate of decay this region could become spotless within a couple of days.
Region 10551 developed slowly with most of the development occurring in the leading and southern spot sections. The The trailing positive polarity field is very close to the leading negative polarity field of the small trailing unnumbered bipolar region., the two regions are likely to merge and there is a possibility of a magnetic delta structure forming at the eastern edge of the large trailing penumbra. A minor M class flare is possible.
New region 10554 rotated into view at the southeastern limb and is a quickly emerging region. There is a magnetic delta structure in the leading penumbra and there is a fair possibility for a minor M class flare. Flare: C2.5 at 13:26 UTC.

Coronal mass ejections (CMEs)

February 5-7: 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 (CH80) will rotate into a geoeffective position on February 9-10.

Processed SOHO/EIT 284 image at 01:06 UTC on February 8. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled February 8-11 and unsettled to active on February 12-13 due to a high speed stream from coronal hole CH80.

Long distance low frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation along long distance north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Rafaela (Argentina) and the southwesterly longwire, Radio Vibración (Venezuela) on the northwesterly EWE. Quite a few stations from the northeasternmost parts of Canada and USA could be heard on frequencies below 1200 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.