Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 12, 2013 at 05:30 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 very quiet on December 11. Solar wind speed at SOHO ranged between 338 and 374 km/.

Solar flux measured at 20h UTC on 2.8 GHz was 170.8 (decreasing 5.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 132.6. The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.6). Three hour interval K indices: 10110001 (planetary), 01102111 (Boulder).

The background x-ray flux was at the class B7 level.

At the time of counting spots (see image time) spots were observed in 13 active regions in 2K resolution (SN: 299) and 11 active regions in 1K resolution (SN: 189) SDO images on the visible solar disk.

Region 11912 [S21W51] was quiet and stable.
Region 11916 [S13W78] decayed slowly and was mostly quiet.
Region 11917 [S16E17] produced a few low level C flares. The region has polarity intermixing and C and minor M class flaring is possible.
Region 11918 [S10E38] developed slowly and quietly.
Region 11919 [S05W53] was quiet and stable.
Region 11920 [N07E48] was quiet and stable.
Region 11922 [N08W31] was mostly quiet and stable.
Region 11923 [N17E14] decayed slowly and quietly.
New region 11924 [S13W58] emerged on December 9 and was numbered by SWPC 2 days later.

Spotted regions not numbered by SWPC:
S2892 [S15W17] decayed slowly and quietly.
S2909 [S25W07] was quiet and stable.
New region S2910 [S07E83] rotated into view.
New region S2911 [N17E29] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

December 9-11: 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) was in 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 12-13. 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 1 1 S21W52 0080 HSX HSX area: 0130
11916 2013.12.04 20 17 7 S12W78 0320 EKC ESC  

 

S2892 2013.12.04   18 4 S15W17 0028   BXO  
11917 2013.12.06
2013.12.07
13 36 17 S15E17 0210 DAI DKI beta-gamma

area: 0330

11923 2013.12.07
2013.12.10
9 16 10 N18E14 0010 BXO BXO area: 0050
S2897 2013.12.07       N15W14         plage
S2898 2013.12.07       N20W33           plage
11918 2013.12.08 7 22 13 S09E38 0160 DAO DAI beta-gamma

area: 0290

11920 2013.12.08
2013.12.09
1 16 6 N12E44 0090 HAX CKO location: N07E48

area: 0540

11922 2013.12.08
2013.12.10
8 28 14 N10W32 0090 DSO DAI area: 0230

location: N08W31

11919 2013.12.08
2013.12.09
3 8 4 S06W52 0020 CRO CRO

area: 0030

S2906 2013.12.08       N09E26         plage
11921 2013.12.09 2     N07E50 0350 HKX       magnetically part of AR 11920
11924 2013.12.09
2013.12.11
2 4 2 S13W59 0020 CRO CRO  
S2908 2013.12.10       S08E15         plage
S2909 2013.12.10   1   S27E05 0002   AXX  
S2910 2013.12.11   1 1 S07E83 0030   HRX    
S2911 2013.12.11   1   N17E29 0001   AXX    
Total spot count: 66 169 79  
Sunspot number: 166 299 189  (total spot count + 10 * number of spotted regions)
Weighted SN: 117 218 128  (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): 100 105 104 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
2013.12 152.1 (1) 41.2 (2A) / 116.2 (2B) / 84.1 (2C) (61.7 projected, -1.3) (6.0)

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.