Solar Terrestrial Activity Report

Last major update issued on March 14, 2006 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 2, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update March 2, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update March 2, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update March 2, 2006)]

Recent activity

The geomagnetic field was inactive to quiet on March 13. Solar wind speed ranged between 349 and 442 (all day average 374) km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 72.6. The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4).
Three hour interval K indices: 00010122 (planetary), 00022000 (Boulder).

The background x-ray flux is below the class A1 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 10858 decayed slowly and quietly.

Spotted regions not numbered by NOAA/SEC:
[S630] This region rotated into view at the southeast limb on March 12. Location at midnight: S03E63.
[S631] A new region emerged in the southwest quadrant on March 13. Location at midnight: S07W66.

Coronal mass ejections (CMEs)

March 11-13: No partly or fully Earth directed CMEs were observed in \LASCO images.

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

No obvious coronal holes are currently in or near Earth facing positions.

Processed SOHO/EIT 284 image at 01:20 UTC on February 28. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet on March 14-16.

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) Effects from a CME are likely to be observed at 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 fair. Propagation on long distance northeast-southwest paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: WLAM Lewiston ME. Propagation was best to the east coast US states. Stations like 610 WIOD Miami FL and 890 WAMG Dedham MA were heard with fair signals while some of the 50 kW stations in New York had strong 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.

Active region Date numbered SEC
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10857 2006.03.05     N08W67     plage
10858 2006.03.12 4 4 N18W01 0020 BXO classification was CSO at midnight
S629 2006.03.06     S15W75     plage
S630 2006.03.12   2 S03E63 0020 HAX  
S631 2006.03.13   3 S07W66 0010 BXO  
Total spot count: 4 9  
SSN: 14 39  

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)
2005.01 102.2 31.3 34.6 (-0.6)
2005.02 97.2 29.2 33.9 (-0.7)
2005.03 89.9 24.5 33.5 (-0.4)
2005.04 86.0 24.2 31.6 (-1.9)
2005.05 99.3 42.7 28.9 (-2.7)
2005.06 93.7 39.3 28.8 (-0.1)
2005.07 96.4 40.1 29.1 (+0.3)
2005.08 90.5 36.4 27.4 (-1.7)
2005.09 91.1 21.9 (25.6 predicted, -1.8)
2005.10 77.0 8.5 (23.8 predicted, -1.8)
2005.11 86.3 18.0 (21.4 predicted, -2.4)
2005.12 90.7 41.2 (18.5 predicted, -2.9)
2006.01 83.4 15.4 (15.4 predicted, -3.1)
2006.02 76.5 4.7 (12.3 predicted, -3.1)
2006.03 74.0 (1) 5.6 (2) (10.1 predicted, -2.2)

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% lower.

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.


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