Solar Terrestrial Activity Report

Last major update issued on March 11, 2005 at 04:40 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 to unsettled on March 10. Solar wind speed ranged between 551 and 769 km/sec, gradually decreasing after noon as the high speed stream from CH149 became less significant.

Solar flux measured at 20h UTC on 2.8 GHz was 101.6. The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 12.6).
Three hour interval K indices: 3333332 (planetary), 33332322 (Boulder).

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

At midnight there were 4 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 developed a larger leading penumbra, however, several of the small trailing spots disappeared. Flare: C7.3 at 11:42 UTC.
Region 10742 added several small spots in the intermediate section. The positive and negative magnetic areas are slowly increasing their separation.
Region 10743 was quiet and stable.

Spotted regions not numbered by NOAA/SEC:
[S524] This region rotated into view at the northeast limb on March 10. Location at midnight: N10E76

Coronal mass ejections (CMEs)

March 8-10: 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.

Processed SOHO/EIT 284 image at 13:06 UTC on March 10. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 11, quiet on March 12 becoming quiet to active on March 13 due to effects from CH151.

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 stations tonight: Radio Vibración (Venezuela) and WWNN Boca Raton FL with fair signals. Propagation in general was best towards Venezuela with strong signals noted on 970 and 1020 kHz. During the local sunrise opening on March 10 Radio 2000 (Venezuela) on 1500 kHz had an excellent signal.

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.