Solar Terrestrial Activity Report

Last major update issued on December 13, 2007 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 October 4, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update October 3, 2007)]

Recent activity

The geomagnetic field was quiet to unsettled on December 12. Solar wind speed ranged between 547 and 684 km/s (average speed was 585 km/s, decreasing 9 km/s from the previous day) under the influence of a high speed stream from CH303.

Solar flux measured at 20h UTC on 2.8 GHz was 93.9. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.3). Three hour interval K indices: 23331002 (planetary), 22342122 (Boulder).

The background x-ray flux is at the class B2 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.

Region 10978 changed significantly and became more compact. Many new spots formed in the northern part of the trailing spot section. Magnetic complexity increased and the opposite polarity areas are currently poorly separated in the central northern part. A minor M class flare is possible.

Coronal mass ejections (CMEs)

December 10-12: No obvious fully or partly Earth directed CMEs were observed in 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 recurrent coronal hole (CH304) in the southern hemisphere will likely rotate into an Earth facing position on December 14-15.

Processed SOHO/EIT 195 image at 00:00 UTC on December 13. The darkest areas on the solar disk are likely coronal holes.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is poor to fair.

Monitoring remarks from a location near N58E06: December 8: Excellent signals were noted on nearly all TA frequencies during my local morning. Stations like 1290 CJBK and 1330 WLOL had huge signals. The Vancouver stations on 1320 and 1470 were occasionally very good.  The best Trans Atlantic propagation sector was 290-320 degrees.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 13. Quiet conditions are likely on December 14-16 becoming unsettled to minor storm on December 17-18 due to CH304.

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.

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
10977 2007.12.02     S05W81     plage
10978 2007.12.06 29 57 S06W12 0200 DAI beta-gamma
classification was DAC at midnight, area 0450
S714 2007.12.07     S05W23     plage
Total spot count: 29 57  
SSN: 39 67  

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)
2006.09 77.8 14.4 15.6 (+0.0)
2006.10 74.3 10.4 14.2 (-1.4)
2006.11 86.3 21.5 12.7 (-1.5)
2006.12 84.5 13.6 12.1 (-0.6)
2007.01 83.3 16.9 12.0 (-0.1)
2007.02 77.7 10.6 11.6 (-0.4)
2007.03 72.2 4.8 10.8 (-0.8)
2007.04 72.4 3.7 9.9 (-0.9)
2007.05 74.4 11.7 8.7 (-1.2)
2007.06 73.7 12.0 (7.5 predicted, -1.2)
2007.07 71.6 10.0 (6.7 predicted, -0.8)
2007.08 69.1 6.2 (6.1 predicted, -0.6)
2007.09 67.1 2.4 (6.2 predicted, +0.1)
2007.10 67.4 0.9 (6.7 predicted, +0.5)
2007.11 69.6 1.7 (7.3 predicted, +0.6)
2007.12 81.4 (1) 10.8 (2) (7.6 predicted, +0.3)

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]