Solar Terrestrial Activity Report

Last major update issued on March 12, 2004 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 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 unsettled to minor storm on March 11. Solar wind speed ranged between 595 and 845 km/sec under the influence of a high speed stream from coronal hole CH84.

Solar flux measured at 20h UTC on 2.8 GHz was 113.2. The planetary A index was 26 (STAR Ap - based on the mean of three hour interval ap indices: 27.6).
Three hour interval K indices: 44434453 (planetary), 54433543 (Boulder).

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

At midnight there were 4 spotted regions on the visible disk. Solar flare activity was low. A single C class event was recorded during the day. 

Region 10569 decayed quietly and could become spotless before rotating over the southwest limb.
Region 10570 decayed in the trailing spot section while several changes were noted in the leading spot section. The main penumbra split into two large penumbrae. Several small patches of positive polarity flux emerged around the leading penumbrae, some places with spots appearing. There is still a magnetic delta structure in the southeastern part of the largest penumbra and an M class flare is possible. Flare: C1.3 at 02:15 UTC.

Spotted regions not numbered by NOAA/SEC:
[S370] This region emerged in the northeast quadrant on March 11. Location at midnight: N18E07.
[S371] This region is rotating into view at the southeast limb. Location at midnight: S12E80.

Coronal mass ejections (CMEs)

March 9-10: No partly or fully earth directed CMEs observed.
March 11: At least a partial halo CME was observed late in the day in LASCO images, most of the ejected material was observed off of the eastern limbs and the north pole. I have not yet been able to determine if the source of this CME was front- or backsided.

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 trans equatorial coronal hole (CH84) was in a geoeffective position on March 7-11.

Processed SOHO/EIT 284 image at 19:06 UTC on March 11. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm with occasional major storm intervals on March 12-14 due to a high speed stream from coronal hole CH84.

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 to poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Vibración (Venezuela). On 1510 kHz WWZN Boston was observed only occasionally with a weak 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.