Solar Terrestrial Activity Report

Last major update issued on November 30, 2006 at 05:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update November 12, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update November 12, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update November 12, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update November 12, 2006)]

Recent activity

The geomagnetic field was quiet to unsettled on November 29. Solar wind speed ranged between 356 and 473 km/s (all day average 402 km/s - decreasing 54 km/s from the previous day). The interplanetary magnetic field swung moderately southwards during the early hours of November 30.

Solar flux measured at 20h UTC on 2.8 GHz was 85.0. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.5). Three hour interval K indices: 23210122 (planetary), 13311121 (Boulder).

The background x-ray flux is at the class A3 level.

At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day.

Region 10926 added rudimentary penumbra on the trailing spot. The region is magnetically fairly simple structured.
Region 10927 developed slowly. Further C flares are possible as there is some polarity intermixing. Flare: C1.0 at 15:18 UTC

Spotted regions not nmbered by NOAA/SEC:
[S685] This region emerged in the southwest quadrant on November 29. Location at midnight: S08W20

Coronal mass ejections (CMEs)

November 27-29: No obvious partly or fully Earth directed CMEs were detected in very incomplete 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 recurrent coronal hole (CH249) in the northern hemisphere was in an Earth facing position on November 26. A recurrent coronal hole (CH250) in the southern hemisphere will likely rotate into an Earth facing position on December 2-3.

Processed SOHO/EIT 284 image at 19:06 UTC on November 24. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on November 30 due to effects from CH249. Mostly quiet conditions are likely on December 1-4.

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 poor to very poor. Propagation on long distance northeast-southwest paths is poor.

Monitoring remarks from a location near N58E06: While there were some stations from North America audible early in the night, almost all TA stations were gone at 05h UTC as a coronal hole related disturbance began.

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
10926 2006.11.24 5 11 S10E19 0210 CAO  
10927 2006.11.27 8 8 N10E32 0120 CAI beta-gamma
classification was DAI at midnight
S683 2006.11.23     S02W39     plage
S685 2006.11.29   2 S08W20 0000 BXO  
Total spot count: 13 21  
SSN: 33 51  

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)
2005.08 90.5 36.4 27.4 (-1.7)
2005.09 91.1 21.9 25.8 (-1.6)
2005.10 77.0 8.7 25.5 (-0.3)
2005.11 86.3 18.0 24.9 (-0.6)
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 17.3 (-1.3)
2006.04 89.0 30.2 17.1 (-0.2)
2006.05 80.9 22.2 (16.8 predicted, -0.3)
2006.06 76.5 13.9 (15.1 predicted, -1.7)
2006.07 75.7 12.2 (13.2 predicted, -1.9)
2006.08 79.0 12.9 (12.7 predicted, -0.5)
2006.09 77.8 14.5 (12.6 predicted, -0.1)
2006.10 74.3 10.4 (11.5 predicted, -1.1)
2006.11 86.4 (1) 29.5 (2) (10.1 predicted, -1.4)

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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