Solar Terrestrial Activity Report

Last major update issued on March 8, 2005 at 04:30 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 active to major storm on March 7. Solar wind speed ranged between 580 and 817 km/sec under the influence of a high speed stream from CH149.

Solar flux measured at 20h UTC on 2.8 GHz was 87.0. The planetary A index was 42 (STAR Ap - based on the mean of three hour interval ap indices: 42.3).
Three hour interval K indices: 55644454 (planetary), 54644444 (Boulder).

The background x-ray flux is at the class A8 level.

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

Region 10741 decayed slightly with small trailing spots in the northeast disappearing. The leading penumbrae merged.
New region 10742 rotated into view at the southeast limb on March 6 and was numbered the next day by SEC. This region developed slowly on March 7 with several small trailing spots emerging.

Spotted regions not numbered by NOAA/SEC:
[S523] This region emerged near the southwest limb on March 7 and somewhat to the southwest of the position of spotless region 10739. SEC and USAF chose to reuse the old region number. Location at midnight: S07W66.

Coronal mass ejections (CMEs)

March 5-7: 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 large recurrent coronal hole (CH149) in the northern hemisphere was in a geoeffective position on March 3-7.

Processed SOHO/EIT 284 image at 19:06 UTC on March 7. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on March 8-9 and quiet to active on March 10 due to a high speed stream from CH149.

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 very poor. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). Surprisingly quite a few stations from Venezuela were audible on frequencies below 1200 kHz. Radio Barcelona on 1080 kHz had a good signal and other stations with fair signals were noted on 640, 660, 780, 790, 830, 850, 880, 8920, 930, 940 and 970 kHz around 03h UTC.

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.