Solar Terrestrial Activity Report

Last major update issued on March 13, 2005 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 March 3, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update March 3, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update March 3, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update March 6, 2005)]

Recent activity

The geomagnetic field was quiet on March 12. Solar wind speed ranged between 349 and 455 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 110.1. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.9).
Three hour interval K indices: 11101121 (planetary), 11212322 (Boulder).

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

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

Region 10741 decayed slowly. Flare: C1.7 at 09:06 UTC.
Region 10742 developed slowly, however, the opposite polarity areas at the center of the region became better separated during the day.
Region 10743 was quiet and stable.

Coronal mass ejections (CMEs)

March 10-12: No obvious fully or partly Earth directed CMEs were 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 (CH151) was in a geoeffective position on March 10. This coronal hole has developed somewhat over the last rotation. A recurrent coronal hole (CH152) in the northern hemisphere will likely rotate to a geoeffective position on March 14. This coronal hole appears to have decayed somewhat over the last rotation.

Processed SOHO/EIT 284 image at 13:06 UTC on March 11. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 13-14, possibly with a few active intervals, due to effects from CH151. Quiet conditions are likely again on March 15-16 while CH152 could cause unsettled to active conditions on March 17-18.

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración with a weak to fair signal, WWNN Boca Raton FL was heard occasionally. Propagation in general was best towards Newfoundland (560, 590, 620, 740, 800 and 930 kHz) and Venezuela (several frequencies).

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.