Solar Terrestrial Activity Report

Last major update issued on January 11, 2007 at 04:55 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update January 11, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 11, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update January 11, 2007)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update December 18, 2006)]

Recent activity

The geomagnetic field was quiet to unsettled on January 10. Solar wind speed ranged between 365 and 476 km/s (all day average 411 km/s - increasing 71 km/s compared to the previous day) under the influence of a weak, low speed coronal hole stream.

Solar flux measured at 20h UTC on 2.8 GHz was 86.2. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.9). Three hour interval K indices: 12222311 (planetary), 03223212 (Boulder).

The background x-ray flux is at the class A6 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 10933 decayed slowly. Further C class flares are possible. Flare: C1.7 at 09:51 UTC.
Region 10935 decayed slowly as the single penumbra lost some of its area.
Region 10937 decayed slowly and was quiet.

Coronal mass ejections (CMEs)

January 8-10: No obvious partly or fully Earth directed CMEs were detected 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 recurrent coronal hole (CH255) in the southern hemisphere will likely rotate into an Earth facing position on January 12-14.

Processed SOHO/EIT 195 image at 15:45 UTC on January 10. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 11 and quiet on January 12-14. A high speed stream from CH255 will likely cause unsettled to minor storm conditions on January 15-17.

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

Monitoring has been temporarily suspended (as of January 1, 2007).

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
10933 2006.12.30 5 4 S04W70 0230 CAO classification was DAO at midnight, area 0170
10934 2006.12.31     N04W67     plage
10935 2007.01.03 1 1 S07W41 0230 HHX classification was HSX at midnight, area 0200
10936 2007.01.06     N10W11     plage
10937 2007.01.08 3 3 S14W21 0020 CSO  
Total spot count: 9 8  
SSN: 39 38  

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)
2005.11 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 17.3 (+0.2)
2006.06 76.5 13.9 16.3 (-1.0)
2006.07 75.7 12.2 (15.0 predicted, -1.3)
2006.08 79.0 12.9 (14.9 predicted, -0.1)
2006.09 77.8 14.5 (14.7 predicted, -0.2)
2006.10 74.3 10.4 (13.5 predicted, -1.2)
2006.11 86.3 21.5 (12.1 predicted, -1.4)
2006.12 84.5 13.6 (11.7 predicted, -0.4)
2007.01 87.8 (1) 12.9 (2) (11.9 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.


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