Solar Terrestrial Activity Report

Last major update issued on February 12, 2004 at 05:20 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 9, 2004)]

Recent activity

The geomagnetic field was quiet to major storm on February 11. Solar wind speed ranged between 341 and 468 km/sec. Solar wind density began to increase at 0930 UTC at ACE. From 11 until 18h UTC the interplanetary magnetic field was moderately to strongly southwards (causing minor to major geomagnetic storming), then swung northwards for the remainder of the day. This disturbance appears to be preceding the high speed stream from coronal hole CH80. Solar wind speed has increased above 600 km/sec as I write this with strong southwards fluctuations observed.

Solar flux measured at 20h UTC on 2.8 GHz was 114.2. The planetary A index was 26 (STAR Ap - based on the mean of three hour interval ap indices: 26.3).
Three hour interval K indices: 21145652 (planetary), 20235553 (Boulder).

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

At midnight there were 6 spotted regions on the visible disk. Solar flare activity was very low. No C class events was recorded during the day.

Region 10549 became spotless early in the day. Then the plage in the region brightened and a new spot emerged. The region will rotate out of view at the northwest limb today.
Region 10551 decayed further with small spots and nearly half of the penumbral area disappearing.
Region 10554 decayed slowly and was quiet.
Region 10555 was quiet and stable.
New region 10556 emerged in the northeast quadrant on February 9 and was numbered by SEC two days later. The region developed slowly on February 11. Interestingly a patch of negative polarity flux emerged in the middle of the leading positive polarity area.

Spotted regions not numbered by NOAA/SEC:
[S351] This region emerged on February 11 in the central western part of coronal hole CH80 near the center of the visible disk. Location at midnight: S09W06.

Coronal mass ejections (CMEs)

February 9-11: 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) was in a geoeffective position on February 9-12.

Processed SOHO/EIT 284 image at 01:06 UTC on February 12. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on February 12-13 and unsettled to active on February 14-15 due to a high speed stream from coronal hole CH80.

Long distance low and medium 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 stations tonight: Radio Cristal del Uruguay and  Radio Vibración (Venezuela), both stations were noted at midnight. At that time quite a few stations from Brazil had strong signals, i.e. Metropolitana on 930, Bandeirantes on 1360 and an unidentified station on 1500 (unfortunately with a soccer commentary)].

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.