Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 29, 2013 at 04:15 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, 2013)] [Cycle 24 progress (last update December 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update December 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update December 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update December 1, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated December 16, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was very quiet on December 28. Solar wind speed at SOHO ranged between 271 and 397 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 134.5 (increasing 4.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 139.5. The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.1). Three hour interval K indices: 10001111 (planetary), 00101221 (Boulder).

The background x-ray flux was at the class B6 level.

At the time of counting spots (see image time) spots were observed in 11 active regions in 2K resolution (SN: 290) and 9 active regions in 1K resolution (SN: 173) SDO images on the visible solar disk.

Region 11931 [S14W57] was quiet and stable.
Region 11936 [S17E07] developed further and has a small magnetic delta structure. C and minor M class flares are possible. C5+ flare: C9.3 at 18:02 UTC
Region 11937 [S12E34] decayed slowly and quietly.
Region 11938 [S12E51] was quiet and stable

Spotted regions not numbered by SWPC:
S2944 [S07W57] reemerged with several spots.
S2948 [S27W00] was quiet and stable.
S2958 [S17W40] developed slowly as the leading polarity area expanded to include parts of a neighboring region. C and M class flares are possible.
S2959 [N18E53] developed slowly and quietly.
New region S2961 [S14E13] emerged early in the day with a penumbra spot.
New region S2962 [S02W46] emerged near the equator with penumbra spots.
New region S2964 [N05W50] emerged with penumbra spots.

A flare a few days behind the west limb was associated with a very wide CME and a small proton event which began late in the day.

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 (CH598) will rotate into an Earth facing position on December 29-31.

Coronal hole map

Propagation

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

Forecast

The geomagnetic field is expected to be quiet on December 29-31 and quiet to active on January 1-3 due to effects from CH598.

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 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
11929 2013.12.16
2013.12.18
      S12W86           location: S13W78

plage

11931 2013.12.18 1 4 2 S15W58 0140 HSX CHO

area: 0260

11934 2013.12.20 15     S18W38 0160 ESI       see AR S2958
11936 2013.12.22
2013.12.23
21 69 37 S17E06 0140 EAC EAC beta-gamma-delta

area: 0300

11935 2013.12.22
2013.12.23
      S06W23           plage
S2941 2013.12.22       N14W26           plage
S2943 2013.12.22       N05W40         plage
S2944 2013.12.23   10 4 S07W57 0040   CRI    
S2945 2013.12.23       N29W42           plage
S2947 2013.12.24       S21E25         plage
S2948 2013.12.24   2   S27W00 0005   AXX  
S2949 2013.12.24       N07E24         plage
S2950 2013.12.24       N13W09           plage
S2951 2013.12.24       N09W48           plage
11937 2013.12.25
2013.12.26
5 15 8 S12E33 0010 BXO BXO area: 0040
S2953 2013.12.25       S22W16         plage
S2954 2013.12.25       N20W30         plage
11938 2013.12.26
2013.12.27
3 6 5 S12E50 0120 HAX HAX  
S2956 2013.12.26       N10W06           plage
S2957 2013.12.27       S09W36         plage
S2958 2013.12.27   60 20 S17W40 0400   ESC  
S2959 2013.12.27   7 3 N19E53 0040   DRO  
S2960 2013.12.27       S12W06         plage
S2961 2013.12.28   1 1 S14E13 0005   AXX    
S2962 2013.12.28   4 3 S02W46 0010   BXO    
S2964 2013.12.28   2   N05W50 0004   AXX    
Total spot count: 45 180 83  
Sunspot number: 95 290 173  (total spot count + 10 * number of spotted regions)
Weighted SN: 65 211 114  (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): 57 102 95 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)
2011.11 153.5 (cycle peak) 96.7 (cycle peak) 61.1 (+1.2) 5.55
2012.02 106.5 32.9 66.9 (+1.4)
possible cycle 24 max
8.81
2012.09 122.9 61.4 58.1 (-0.1) 8.07
2012.10 123.3 53.3 58.6 (+0.5) 9.97
2012.11 121.3 61.8 59.7 (+1.1) 7.08
2012.12 108.6 40.8 59.6 (-0.1) 3.44
2013.01 127.1 62.9 58.7 (-0.9) 4.69
2013.02 104.3 38.0 58.4 (-0.3) 6.11
2013.03 111.3 57.9 57.5 (-0.9) 10.56
2013.04 124.8 72.4 57.9 (+0.4) 5.40
2013.05 131.4 78.7 59.9 (+2.0) 9.73
2013.06 110.1 52.5 (62.2 projected, +2.3) 12.60
2013.07 115.5 57.0 (63.9 projected, +1.7) 9.47
2013.08 114.6 66.0 (64.8 projected, +0.9) 8.27
2013.09 102.6 36.9 (65.6 projected, +0.8) 5.23
2013.10  132.1 85.6 (64.9 projected, -0.7) 7.71
2013.11  148.3 77.6 (63.0 projected, -1.9) 5.68
2013.12 148.3 (1) 107.1 (2A) / 118.5 (2B) / 91.0 (2C) (61.7 projected, -1.3) (4.6)

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 the 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.