Solar Terrestrial Activity Report

Last major update issued on March 6, 2005 at 04:10 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 February 16, 2005)]

Recent activity

The geomagnetic field was quiet to unsettled on March 5. Solar wind speed ranged between 352 and 422 km/sec under the influence of a low speed stream from CH150. Early on March 6 it is obvious that more significant effects from CH149 have arrived. 

Solar flux measured at 20h UTC on 2.8 GHz was 81.2. The planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 9.6).
Three hour interval K indices: 13222233 (planetary), 13322223 (Boulder).

The background x-ray flux is at the class A6 level.

At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day.

Region 10741 developed slowly and could produce further C class flares. Flare: C1.1 at 20:07 UTC.

Coronal mass ejections (CMEs)

March 3-4: No obvious fully or partly Earth directed CMEs were observed.

No images from March 5 were available when I was writing this.

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 coronal hole (CH149) in the northern hemisphere was in a geoeffective position on March 3-6.

Processed SOHO/EIT 284 image at 01:06 UTC on March 6. 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 6-9 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 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 (Venezuela). Before 0230 UTC there were quite a few signals from the US, i.e. WIOD on 610 kHz had a poor to fair signal. later on the only North American stations heard were from Newfoundland. VOCM 590, VOWR 800 and CJYQ on 930 kHz all had fair signals.

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.