Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 4, 2013 at 04:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update January 1, 2013)] [Cycle 24 progress (last update January 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update January 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update January 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update January 2, 2013)]

[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 January 3. Solar wind speed at SOHO ranged between 271 and 294 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 128.8 (increasing 31.7 over the last solar rotation). The Potsdam WDC planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.1). Three hour interval K indices: 01000000 (planetary), 01001221 (Boulder).

The background x-ray flux was at the class B4 level.

At midnight UTC the visible solar disk had 14 spotted active regions (in 2K resolution SDO images).

Region 11638 [N13W20] was quiet and stable.
Region 11640 [N27W35] developed further adding penumbral area. Although the region only has minor polarity intermixing, there's a chance of an M class flare.
Region 11641 [N03E08] was quiet and stable.
Region 11642 [S24E36] decayed slowly and quietly.
Region 11643 [S14E33] was quiet and stable.
Region 11644 [N15E48] was quiet and stable.
New region 11645 [S13W04] emerged on January 2 and was numbered by SWPC the next day.
New region 11646 [N13E57] rotated into view on January 2 with SWPC numbering the region the following day.

Spotted regions not numbered by NOAA/SWPC:
S2149 [N04E66] developed slowly and was quiet.
S2151 [N20E64] was quiet and stable.
S2153 [N16W38] was quiet and stable. The region could soon merge with AR S2154.
S2154 [N15W42] developed slowly and quietly.
New region S2155 [S15E85] rotated into view with a single spot.
New region S2156 [N17E57] emerged with a tiny spot.

Coronal mass ejections (CMEs)

January 1-3: 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 small recurrent trans equatorial coronal hole (CH549) will be in an Earth facing position on January 3-4.

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 January 4-6. Quiet to unsettled conditions are possible on January 7 due to weak effects from CH549.

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 2K resolution) 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
11637 2012.12.24
2012.12.26
      N06W63           plage
11636 2012.12.24
2012.12.25
      N14W55         plage
11639 2012.12.26
2012.12.27
      S16W24         plage
11638 2012.12.26
2012.12.27
2 6 5 N13W21 0100 HSX CSO area: 0180
S2132 2012.12.26       S14W45           plage
S2133 2012.12.28       N18W15           plage
S2135 2012.12.28       S17W35         plage
11641 2012.12.29
2012.12.31
1 7 4 N05E07 0050 HSX CSO location: N03E08

area: 0120

S2138 2012.12.29       N03W17           plage
11640 2012.12.29
2012.12.30
28 31 17 N28W35 0240 EAI EAI area: 0500
S2142 2012.12.29       N13W36           plage
11642 2012.12.30
2012.12.31
1 3 1 S24E34 0080 HSX CSO location: S24E36

area: 0160

11643 2012.12.31
2013.01.02
  3 1 S14E31 0010   BXO  
11644 2013.01.01
2013.01.02
2 3 2 N14E48 0060 HSX HSX  
S2149 2013.01.02   4 2 N04E66 0020   CRO  
11646 2013.01.02
2013.01.03
1 1 1 N13E57 0080   HSX  
S2151 2013.01.02   1 1 N20E64 0010   HRX  
11645 2013.01.02
2013.01.03
11 15 10 S13W05 0030 DRO DRI area: 0080
S2153 2013.01.02   2 1 N16W38 0000   BXO  
S2154 2013.01.02   5 2 N15W42 0020   CRO  
S2155 2013.01.03   1 1 S15E85 0150   HSX    
S2156 2013.01.03   1   N17E57 0000   AXX    
Total spot count: 46 83 48  
Sunspot number: 116 223 178  (total spot count + 10 * number of spotted regions)
Weighted SN: 79 130 95  (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): 70 78 98 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)
2011.10 137.3 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 58.9 (-2.8) 10.08
2012.07 133.9 66.5 (57.4 projected, -1.5) 13.90
2012.08 115.4 63.1 (58.3 projected, +0.9) 7.96
2012.09 122.9 61.5 (58.9 projected, +0.6) 8.07
2012.10 123.3 53.3 (58.3 projected, -0.6) 9.97
2012.11 121.3 61.4 (57.6 projected, -0.7) 7.08
2012.12 108.6 40.8 (56.9 projected, -0.7) 3.34
2013.01 121.9 (1) 9.8 (2A) / 101.7 (2B) / 47.1 (2C) (56.2 projected, -0.7) (2.00)

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.