Solar Terrestrial Activity Report

Last major update issued on January 1, 2011 at 06:00 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]
[Annotated geomagnetic activity chart - Carrington rotation 2104 - NEW]

Recent activity

The geomagnetic field was quiet on December 31. Solar wind speed ranged between 294 and 366 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 90.9 (up 3.5 over the last solar rotation). The planetary A index  was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.0). Three hour interval K indices: 11121200 (planetary), 10221211 (Boulder).

The background x-ray flux is at the class A9 level.

At midnight UTC the visible solar disk had 5 spotted regions.

Region 11138 became spotless early in the day, then regained a spot late in the day. Flare: C1.3 at 04:25 UTC associated with a weak type II radio sweep.
Region 11139 redeveloped a few small spots.
New region 11140 rotated partly into view at the northeast limb on December 30 and was numbered the next day by NOAA/SWPC.

Spotted regions not numbered by NOAA/SWPC:
[S855] A new region emerged late on December 30 in the northern hemisphere near the central meridian. Quick development was observed early on December 31. Location at midnight: N33W12.
[S857] This region emerged on December 31 in the southeast quadrant. Location at midnight: S13E47

Coronal mass ejections (CMEs)

December 29-31: No obviously Earth directed CMEs were observed in LASCO or STEREO images.

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 coronal hole (CH431) in the northern hemisphere will likely rotate into an Earth facing position on January 4. A recurrent trans equatorial coronal hole (CH432) will probably become Earth facing on January 5.

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 on January 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.

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
11137 2010.12.25     N18W55            
11138 2010.12.27 2 1 N12W70 0010 BXO AXX the base image source is SOHO/MDI continuum
11139 2010.12.27   3 S26E20 0010   BXO   image source SOHO/MDI
S854 2010.12.30     S25W20         plage
 

image source SOHO/MDI
S855 2010.12.30   7 N33W12 0100   DAO image source SOHO/MDI
11140 2010.12.31 1 2 N32E67 0180 HSX HSX formerly region S856

image source SOHO/MDI
S857 2010.12.31   5 S13E47 0030   CSO   image source SOHO/MDI
Total spot count: 3 18  
Sunspot number: 23 68  

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 84.2 (1) 21.3 (2B) (28.6 predicted, +2.5) (3.41)

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.