Solar Terrestrial Activity Report

Last major update issued on March 2, 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 January 2, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 2, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 2, 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 active on March 1. Solar wind speed ranged between 577 and 732 km/sec under the influence of a high speed stream from CH148.

Solar flux measured at 20h UTC on 2.8 GHz was 73.7 (lowest level since August 4, 1997). The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.5).
Three hour interval K indices: 21332224 (planetary), 22332313 (Boulder).

The background x-ray flux is at the class A1 level.

At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Spotted regions not numbered by NOAA/SEC:
[S520] This region emerged on March 1 near the center of the visible solar disk. Location at midnight: S07W12

Coronal mass ejections (CMEs)

February 27-March 1: 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 (CH148) was in a geoeffective position on February 23-25. A recurrent coronal hole (CH149) in the northern hemisphere will likely rotate to a geoeffective position on March 4-5. A small recurrent trans equatorial coronal hole (CH150) will likely be in a geoeffective position on March 2.

Processed SOHO/EIT 284 image at 01:06 UTC on March 1. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to unsettled on March 2 due to coronal hole effects and mostly quiet on March 3-4. Weak effects from CH150 are possible on March 5 with occasional unsettled and active intervals.

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

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.


Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. 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 WLAM Lewiston ME. Propagation was best on frequencies below 1100 kHz with stations from Newfoundland, New York and Florida having the best signals. Good propagation was observed during the local sunrise opening on March 1 with WZON Bangor ME on 620 kHz making it past the usually much stronger signal of CKCM. At the same time WIOD Miami 610 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.

Active region Date numbered SEC
Location at midnight Area Classification Comment
10738 2005.02.23     S10W68     plage
10739 2005.02.26 1   S03E10 0010 AXX spotless for the third consecutive day
S519 emerged on
    N19W80     plage
S520 emerged on
  1 S07W12 0020 HAX  
Total spot count: 1 1  
SSN: 11 11  

Monthly solar cycle data

Month Average solar
flux at Earth
International sunspot number Smoothed sunspot number
2000.04 184.2 125.5 120.8
cycle 23 sunspot max.
2000.07 202.3 170.1 119.8
2001.12 235.1 132.2 114.6 (-0.9)
2004.01 114.1 37.3 52.0 (-2.8)
2004.02 107.0 45.8 49.3 (-2.7)
2004.03 112.0 49.1 47.1 (-2.2)
2004.04 101.2 39.3 45.5 (-1.6)
2004.05 99.8 41.5 43.9 (-1.6)
2004.06 97.4 43.2 41.7 (-2.2)
2004.07 119.1 51.0 40.3 (-1.4)
2004.08 109.6 40.9 39.2 (-1.1)
2004.09 103.1 27.7 (37.4 predicted, -1.8)
2004.10 105.9 48.4 (35.2 predicted, -2.2)
2004.11 113.2 43.7 (33.3 predicted, -1.9)
2004.12 94.5 17.9 (31.0 predicted, -2.3)
2005.01 102.2 31.3 (28.3 predicted, -2.7)
2005.02 97.2 29.1 (25.9 predicted, -2.4)
2005.03 73.7 (1) 0.4 (2) (24.1 predicted, -1.8)

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.

[DX-Listeners' Club]