Solar Terrestrial Activity Report

Last major update issued on March 5, 2005 at 05:35 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 on March 4. Solar wind speed ranged between 360 and 465 km/sec, gradually decreasing all day. Wind density began increasing slowly after 18h UTC indicating the approach of a low speed stream from CH150. Early on March 5 wind speed began to increase as well and the interplanetary magnetic field has been mostly southwards after midnight.

Solar flux measured at 20h UTC on 2.8 GHz was 78.9. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.9).
Three hour interval K indices: 10001110 (planetary), 10101111 (Boulder).

The background x-ray flux is at the class A4 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.

New region 10741 rotated into view at the northeast limb on March 3 and was numbered the next day by SEC.

Coronal mass ejections (CMEs)

March 2-4: 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 coronal hole (CH149) in the northern hemisphere will rotate to a geoeffective position on March 3-6. A small recurrent trans equatorial coronal hole (CH150) was in a geoeffective position on March 2. A new coronal hole may have formed on March 4 near the center of the visible disk.

Processed SOHO/EIT 284 image at 13:21 UTC on March 4. The darkest areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be quiet to active March 5 due to weak effects from CH150. A stronger disturbance from CH149 could arrive on March 6 or 7 and cause unsettled to minor storm conditions until March 9.

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 station tonight: WWNN Boca Raton FL. Propagation at 04h UTC favored stations from Cuba and Florida, some of the Newfoundland stations had strong signals as well. On 620 kHz Radio Rebelde (Cuba) had clearly the best signal, usually the Newfoundland station is dominating the frequency.

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
10739 2005.02.26     S03W29     plage
10740 2005.03.02     S07W50     plage
10741 2005.03.04 3 2 N12E70 0110 CAO formerly region S521
classification was HAX at midnight, area 0080
location: N15E68
Total spot count: 3 2  
SSN: 13 12  

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 76.1 (1) 1.9 (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]