Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 11, 2013 at 05:05 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 3, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to unsettled on December 10. Solar wind speed at SOHO ranged between 348 and 472 km/.

Solar flux measured at 20h UTC on 2.8 GHz was 175.2 (increasing 4.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 131.8. The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.9). Three hour interval K indices: 13111000 (planetary), 12222111 (Boulder).

The background x-ray flux was at the class B8 level.

At the time of counting spots (see image time) spots were observed in 14 active regions in 2K resolution (SN: 329) and 12 active regions in 1K resolution (SN: 218) SDO images on the visible solar disk.

Region 11912 [S21W38] was quiet and stable.
Region 11916 [S13W65] was quiet and stable.
Region 11917 [S17E29] developed slowly and quietly.
Region 11918 [S10E52] was mostly quiet and stable.
Region 11919 [S06W38] decayed slowly and quietly.
Region 11920 [N07E62] was quiet and stable.
New region 11922 [N08W17] emerged on December 8 and was numbered by SWPC 2 days later. The region developed quickly on December 10 and could produce C flares.
New region 11923 [N17E28] emerged on December 7 with SWPC numbering the region 3 days later.

Spotted regions not numbered by SWPC:
S2892 [S16W01] developed slowly and quietly.
S2897 [N15W01] was quiet and stable. The region has reversed polarities.
S2906 [N09E39] was quiet and stable.
S2907 [S13W46] developed slowly and quietly.
New region S2908 [S08E28] emerged with penumbra spots.
New region S2909 [S27E05] emerged with penumbra spots.

Coronal mass ejections (CMEs)

December 8-10: 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 large northern hemisphere coronal hole (CH597) will rotate into an Earth facing position on December 11.

Coronal hole map

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. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on December 11-13. A high speed stream from CH597 could cause unsettled and active intervals on December 14-15.

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
11912 2013.12.01
2013.12.02
1 5 3 S21W38 0080 HSX CSO area: 0140
11916 2013.12.04 27 29 16 S12W64 0350 EKC EAC  

area: 0450

S2892 2013.12.04   28 9 S16W01 0060   CRI  
11917 2013.12.06
2013.12.07
18 37 20 S17E31 0250 DKI CHI beta-gamma

area: 0380

11923 2013.12.07
2013.12.10
5 22 14 N17E28 0010 BXO DRI area: 0070
S2897 2013.12.07   3 3 N15W01 0025   BXO reversed polarities
S2898 2013.12.07       N20W21           plage
11918 2013.12.08 8 12 6 S09E51 0170 DAO DKO beta-gamma

area: 0270

S2901 2013.12.08       N31W53           plage
11920 2013.12.08
2013.12.09
1 15 6 N12E57 0060 HAX CKO location: N08E76

area: 0520

11922 2013.12.08
2013.12.10
14 20 14 N12W16 0120 DAO DAI area: 0220

location: N08W17

11919 2013.12.08
2013.12.09
3 9 3 S06W38 0020 CRO CRO

area: 0040

S2906 2013.12.08   2 2 N09E39 0008   AXX  
11921 2013.12.09 2     N06E62 0350 HKX       magnetically part of AR 11920
S2907 2013.12.09   3 2 S13W46 0050   DRO  
S2908 2013.12.10   2   S08E28 0004   AXX    
S2909 2013.12.10   2   S27E05 0004   BXO    
Total spot count: 79 189 98  
Sunspot number: 169 329 218  (total spot count + 10 * number of spotted regions)
Weighted SN: 132 246 155  (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): 101 115 120 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
2012.08 115.4 63.0 58.2 (+0.4) 7.96
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
2013.12 150.3 (1) 35.9 (2A) / 111.2 (2B) / 82.5 (2C) (61.7 projected, -1.3) (6.4)

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.