Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 29, 2012 at 05:10 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update December 1, 2012)] [Cycle 24 progress (last update December 2, 2012) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update December 1, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update December 1, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update December 7, 2012)]

[POES auroral activity level since October 2009 - updated October 7, 2012]
[Solar polar fields vs solar cycles - updated December 22, 2012]

Recent activity

The geomagnetic field was very quiet on December 28. Solar wind speed at SOHO ranged between 271 and 287 km/s. A low speed stream, probably from CH548, began to influence the geomagnetic field late in the day. Solar wind speed has increased slowly early on December 29.

Solar flux measured at 20h UTC on 2.8 GHz was 105.8 (increasing 4.1 over the last solar rotation). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 1.8). Three hour interval K indices: 00000011 (planetary), 00000110 (Boulder).

The background x-ray flux was at the class B2 level.

At midnight UTC the visible solar disk had 11 spotted active regions (in 2K resolution SDO images).

Region 11635 [N11W60] decayed further with only a few small spots remaining by the end of the day.
Region 11636 [N11E22] was quiet and stable.
Region 11637 [N05E22] was quiet and stable.
Region 11638 [N12E58] was quiet and stable.
Region 11639 [S17E58] decayed slowly and quietly.

Spotted regions not numbered by NOAA/SWPC:
S2131 [N17W10] regained a leader spot.
S2132 [S14E35] reemerged with a tiny spot.
New region S2133 [N18E63] emerged with a small spot.
New region S2134 [N19W36] emerged with several spots.
New region S2135 [S16E44] emerged with tiny spots.
New region S2136 [S20W10] emerged with a tiny spot.

Coronal mass ejections (CMEs)

December 26-28: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

Coronal holes

Coronal hole history (since October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent trans equatorial coronal hole (CH548) was in an Earth facing position on December 23-24. CH548 did not cause any significant disturbance during the previous rotation.

Coronal hole map

The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using this method, the extent and intensity of both CHs are consistent with other data sources.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet on December 29-31. There's a chance of unsettled intervals on December 29 due to weak coronal hole effects. 

Coronal holes (1) Coronal mass ejection (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

Click on image for higher resolution image) Compare to the previous day's image. 0.5k image

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.

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
detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
2K 1K
11635 2012.12.18 7 3 1 N12W57 0050 CAO BXO

location: N11W60

area: 0010

S2119 2012.12.20       N07W44           plage
11637 2012.12.24
2012.12.26
1 2 1 N06E20 0010 AXX AXX location: N05E22
11636 2012.12.24
2012.12.25
  5 1 N09E16 0010   BXO location: N11E22
S2127 2012.12.25       S09W53           plage
S2128 2012.12.26       S13E04           plage
11639 2012.12.26
2012.12.27
5 8 4 S16E56 0090 DAO DAO location: S17E58
11638 2012.12.26
2012.12.27
1 3 1 N12E56 0150 HSX HHX area: 0260

location: N11E58

S2131 2012.12.26   1   N17W10 0000   AXX  
S2132 2012.12.26   1   S14E35 0000   AXX    
S2133 2012.12.28   1 1 N18E63 0000   AXX    
S2134 2012.12.28   5 3 N19W36 0010   BXO    
S2135 2012.12.28   3 2 S16E44 0010   BXO    
S2136 2012.12.28   1   S20W10 0000   AXX    
Total spot count: 14 33 14  
Sunspot number: 54 143 94  (total spot count + 10 * number of spotted regions)
Weighted SN: 29 48 29  (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number): 32 50 52 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
2011.09 133.8 78.0 59.5 (+0.5) 12.27
2011.10 137.3 88.0 59.9 (+0.4) 8.28
2011.11 153.5 (cycle max) 96.7 (cycle max) 61.1 (+1.2) 5.55
2011.12 141.3 73.0 63.4 (+2.3) 3.78
2012.01 132.5 58.3 65.5 (+2.1) 7.15
2012.02 106.5 32.9 66.9 (+1.4)
possible cycle 24 max
8.81
2012.03 114.7 64.3 66.8 (-0.1) 16.08
2012.04 113.0 55.2 64.6 (-2.2) 10.10
2012.05 121.5 69.0 61.7 (-2.9) 7.06
2012.06 119.6 64.5 (59.5 projected, -2.2) 10.08
2012.07 133.9 66.5 (58.8 projected, -0.7) 13.90
2012.08 115.4 63.1 (60.1 projected, +1.3) 7.96
2012.09 122.9 61.5 (61.1 projected, +1.0) 8.07
2012.10 123.3 53.3 (60.7 projected, -0.4) 9.97
2012.11 121.3 61.4 (60.0 projected, -0.7) 7.08
2012.12 108.6 (1) 54.8 (2A) / 60.7 (2B) / 39.2 (2C) (59.3 projected, -0.7) (3.37)

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 SIDC international sunspot number is typically 30-50% lower. 2B) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC 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.