Solar Terrestrial Activity Report

Last major update issued on March 22, 2007 at 04:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update March 10, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update March 10, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update March 10, 2007)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update February 6, 2007)]

Recent activity

The geomagnetic field was very quiet on March 21. Solar wind speed ranged between 277 and 299 km/s (average speed was 285 km/s, decreasing 16 km/s from the previous day).

Solar flux measured at 20h UTC on 2.8 GHz was 72.8. The planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.1). Three hour interval K indices: 00000110 (planetary), 00111200 (Boulder).

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

At midnight the visible solar disk was spotless. The solar flare activity level was very low. No C class events were recorded during the day. Two plage areas rotated into view at the east limb, none of which had any spots.

Coronal mass ejections (CMEs)

March 19-21: No obvious fully or partially Earth directed CMEs were observed in LASCO imagery.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A small coronal hole (CH261) in the southern hemisphere was in an Earth facing position on March 18-19. An elongated recurrent trans equatorial coronal hole (CH262) will rotate into an Earth facing position on March 20-23.

Processed SOHO/EIT 195 image at 00:00 UTC on March 22. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 22-23 due to weak effects from CH261, occasional active intervals are possible. Quiet to active conditions are likely on March 24-27 as a stream from CH262 becomes geoeffective, occasional minor storm intervals are possible on March 24-26.

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

Daily monitoring will not resume until a local noise problem (related to construction work on a neighboring property) has been fixed. Occasional monitoring reports will be submitted when propagation is good.

February 18, 2007: Strong signals were noted from a number of USA east coast stations as well as from stations located in the Canadian Atlantic provinces. CFDR on 780 kHz was particularly strong.

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
               
Total spot count: 0 0  
SSN: 0 0  

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)
2005.12 90.7 41.1 23.0 (-1.9)
2006.01 83.4 15.3 20.8 (-2.2)
2006.02 76.5 4.9 18.6 (-2.2)
2006.03 75.4 10.6 17.4 (-1.2)
2006.04 89.0 30.2 17.1 (-0.3)
2006.05 80.9 22.3 17.3 (+0.2)
2006.06 76.5 13.9 16.3 (-1.0)
2006.07 75.7 12.2 15.3 (-1.0)
2006.08 79.0 12.9 15.6 (+0.3)
2006.09 77.8 14.4 (15.6 predicted, +0.0)
2006.10 74.3 10.4 (14.4 predicted, -1.2)
2006.11 86.3 21.5 (12.8 predicted, -1.6)
2006.12 84.5 13.6 (11.9 predicted, -0.9)
2007.01 83.3 16.9 (11.5 predicted, -0.4)
2007.02 77.7 10.6 (11.4 predicted, -0.1)
2007.03 71.7 (1) 5.6 (2) (11.6 predicted, +0.2)

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.


[DX-Listeners' Club]