Solar Terrestrial Activity Report

Last major update issued on March 14, 2004 at 04:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update March 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update March 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update March 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16, 2004)]
[Archived reports (last update March 11, 2004)]

Recent activity

The geomagnetic field was quiet to active on March 13. Solar wind speed ranged between 458 and 567 km/sec, generally slowly decreasing all day as the high speed stream from coronal hole CH84 ended.

Solar flux measured at 20h UTC on 2.8 GHz was 103.8. The planetary A index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 15.5).
Three hour interval K indices: 31434422 (planetary), 31433322 (Boulder).

The background x-ray flux is at the class B1-B2 level.

At midnight there were 3 spotted regions on the visible disk. Solar flare activity was very low. No C class events was recorded during the day. 

Region 10570 decayed further and lost all penumbra on the trailing spots. The penumbra containing the magnetic delta structure lost more than half of its area. A minor M class flare is still possible.
Region 10572 developed slowly and quietly.
Region 10573 lost a couple of spots and the penumbra became less asymmetrical.

Coronal mass ejections (CMEs)

March 11-13: 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 coronal hole in the northeast quadrant appears to be too far to the north to become geoeffective.

Processed SOHO/EIT 284 image at 19:06 UTC on March 13. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 14-18.

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 poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela) with a weaker than usual signal].

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 some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.