Solar Terrestrial Activity Report

Last major update issued on December 17, 2010 at 05:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update December 3, 2010)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update December 3, 2010)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update December 3, 2010)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports from January 2003 (last update December 3, 2010)]

[POES auroral activity level charts since October 2009]

Recent activity

The geomagnetic field was quiet on December 16. Solar wind speed ranged between 433 and 567 km/s under the influence of a high speed stream associated with CH430.

Solar flux measured at 20h UTC on 2.8 GHz was 84.1 (up 0.1 over the last solar rotation). The planetary A index  was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 21210111 (planetary), 21220221 (Boulder).

The background x-ray flux is at the class A8 level.

At midnight UTC the visible solar disk had 1 spotted region.

Region 11135 did not change significantly and continues to produce occasional B flares.

Coronal mass ejections (CMEs)

December 15-16: No obviously Earth directed CMEs were observed in LASCO or STEREO images.
December 14: The long duration event in the northwest quadrant on December 14 produced a partial halo CME. While the core of the CME is not Earth directed, there's a chance of a flank impact on December 18. However, as Earth may then be under the influence of a high speed stream from CH430, the CME could easily be absorbed into that stream and not cause any observable effects.

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

An elongated, curved, trans equatorial coronal hole (CH430) was in an Earth facing position on December 12-16.

Image courtesy of SDO (NASA) and the AIA consortium. Annotations are my own. 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 to fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 17-19 due to effects from CH430.

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/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.

Active region Date numbered Spot count Location at midnight Area Classification SDO (NASA) / AIA 4500
image
Comment
SWPC STAR SWPC STAR Current Previous
11133 2010.12.04 1   N16W94 0060 HSX     rotated out of view
11134 2010.12.13     N18W72           plage
11135 2010.12.13 2 1 N19E17 0020 BXO AXX  
Total spot count: 3 1  
Sunspot number: 23 11  

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
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)  
2008.07 65.7 (SF minimum) 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
3.25
2009.09 70.5 4.3 6.2 (+1.4) 3.88 / 3.61
2009.10 72.6 4.8 7.1 (+0.9) 3.66 / 3.56
2009.11 73.6 4.1 7.6 (+0.5) 2.45 / 2.63
2009.12 76.7 10.8 8.3 (+0.7) 1.41 / 1.92
2010.01 81.1 13.2 9.3 (+1.0) 2.93 / 3.07
2010.02 84.7 18.8 10.6 (+1.3) 4.15 / 4.61
2010.03 83.4 15.4 12.3 (+1.7) 4.58 / 4.65
2010.04 75.9 8.0 14.0 (+1.7) 10.22 / 10.24
2010.05 73.8 8.7 15.5 (+1.5) 9.18 / 8.15
2010.06 72.5 13.6 (16.9 predicted, +1.4) 8.17 / 6.85
2010.07 79.8 16.1 (18.4 predicted, +1.5) 6.31 / 5.15
2010.08 79.2 19.6 (19.6 predicted, +1.2) 8.49 / 7.77
2010.09 81.1 25.2 (20.8 predicted, +1.2) 5.33 / 5.45
2010.10 81.6 23.5 (23.2 predicted, +2.4) 6.07 / 6.27
2010.11 82.5 21.6 (26.1 predicted, +2.9) 4.80
2010.12 87.4 (1) 15.7 (2A) / 30.4 (2B) (28.6 predicted, +2.5) (3.28)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the daily SWPC ap indices. Values in red are based on the official NGDC ap indices.

This report has been prepared by Jan Alvestad. It is based on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.

SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.