Solar Terrestrial Activity Report

Last major update issued on January 2, 2011 at 04:00 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update January 2, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update January 2, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update January 2, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports from January 2003 (last update January 1, 2011)]

[POES auroral activity level charts since October 2009]
[Annotated geomagnetic activity chart - Carrington rotation 2104 - NEW]

Recent activity

The geomagnetic field was quiet on January 1. Solar wind speed ranged between 285 and 346 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 91 (up 3.1 over the last solar rotation). The planetary A index  was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4). Three hour interval K indices: 00011112 (planetary), 00122212 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight UTC the visible solar disk had 3 spotted regions.

Region 11140 was mostly quiet and unchanged.
New region 11141 emerged in the northern hemisphere on December 30 and was noticed by NOAA/SWPC two days later. The region decayed slowly on January 1.
New region 11142 emerged in the southeast quadrant on December 31 and was numbered by NOAA/SWPC the next day. The region is developing and could produce C flares.

Coronal mass ejections (CMEs)

December 30 - January 1: 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 fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on January 2-5.

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     N18W68            
11138 2010.12.27 2   N12W82 0010 AXX     spotless

the base image source is SOHO/MDI continuum

11139 2010.12.27 1   S30E03 0000 AXX     spotless

image source SOHO/MDI

S854 2010.12.30     S25W33           plage
11141 2011.01.01 6 7 N35W25 0100 DSO DSO formerly region S855
area: 0080

image source SOHO/MDI

11140 2010.12.31 1 1 N32E52 0200 HSX HSX

image source SOHO/MDI

11142 2011.01.01 5 10 S14E33 0040 DSO DAI formerly region S857
area: 0090

image source SOHO/MDI

Total spot count: 15 18  
Sunspot number: 65 48  

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
2008.07 65.7 (SF minimum) 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
3.25
2009.10 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 16.4 (+0.9) 8.17 / 6.85
2010.07 79.8 16.1 (17.0 predicted, +0.6) 6.31 / 5.15
2010.08 79.2 19.6 (17.9 predicted, +0.9) 8.49 / 7.77
2010.09 81.1 25.2 (19.0 predicted, +1.1) 5.33 / 5.45
2010.10 81.6 23.5 (20.7 predicted, +1.7) 6.07 / 6.27
2010.11 82.5 21.6 (23.0 predicted, +2.3) 4.80
2010.12 84.2 14.5 (25.3 predicted, +2.3) 3.41
2011.01 91 (1) 2.1 (2A) / 65.0 (2B) (27.7 predicted, +2.4) (3.38)

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.