Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 28, 2013 at 06:55 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 27. Solar wind speed at SOHO ranged between 271 and 365 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 130.6 (decreasing 0.6 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 139.2. The Potsdam WDC planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.4). Three hour interval K indices: 00000010 (planetary), 00000221 (Boulder).

The background x-ray flux is at the class B5 level.

At the time of counting spots (see image time) spots were observed in 14 active regions in 2K resolution (SN: 292) and 11 active regions in 1K resolution (SN: 184) SDO images on the visible solar disk.

Region 11931 [S15W37] was quiet and stable.
Region 11936 [S17E19] developed further and has significant polarity intermixing. C and minor M class flares are possible.
Region 11937 [S13E47] was quiet and stable.
New region 11938 [S13E64] rotated into view on December 26 and was numbered by SWPC the next day.

Spotted regions not numbered by SWPC:
S2943 [N05W27] was quiet and stable.
S2947 [S21E38] was quiet and stable.
S2948 [S27E13] was quiet and stable.
S2949 [N07E37] was quiet and stable.
S2953 [S22W03] developed slowly and quietly.
S2954 [N20W17] was quiet and stable.
New region S2957 [S09W23] emerged with penumbra spots to the northeast of AR 11931.
New region S2958 [S19W23] was split off when new flux emerged inside what used to be the trailing polarity area of AR 11931. The region could produce C and M class flares.
New region S2959 [N18E66] emerged near the northeast limb with a penumbra spot.
New region S2960 [S12E07] emerged with penumbra spots.

Coronal mass ejections (CMEs)

December 25-27: 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 high and upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet on December 28-31 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
      S12W72         location: S13W65

plage

11930 2013.12.17
2013.12.18
1     S08W89 0030 HSX    

rotated out of view

11931 2013.12.18 3 20 9 S15W43 0160 CAO FKO images/AR_11931_20131226_2345.png beta-gamma

area: 0500

location: S15W37

11934 2013.12.20 15     S16W26 0190 ESI       see AR 11931 and AR S2858
11936 2013.12.22
2013.12.23
12 52 28 S16E19 0110 EAI EAC beta-gamma

area: 0350

11935 2013.12.22
2013.12.23
1     S06W08 0000 AXX     plage
S2941 2013.12.22       N14W13           plage
S2943 2013.12.22   1   N05W27 0003   AXX  
S2944 2013.12.23       S05W43           plage
S2945 2013.12.23       N29W29           plage
S2947 2013.12.24   1 1 S21E38 0010   AXX  
S2948 2013.12.24   2   S27E13 0004   AXX  
S2949 2013.12.24   2 2 N07E37 0009   BXO  
S2950 2013.12.24       N13E04           plage
S2951 2013.12.24       N09W35           plage
11937 2013.12.25
2013.12.26
4 12 7 S12E46 0020 BXO DRI area: 0040
S2953 2013.12.25   4 2 S22W03 0013   AXX  
S2954 2013.12.25   1   N20W17 0002   AXX  
11938 2013.12.26
2013.12.27
1 6 3 S12E62 0060 HAX HAX location: S13E64

area: 0130

S2956 2013.12.26       N10E07         plage
S2957 2013.12.27   2 2 S09W23 0010   BXO    
S2958 2013.12.27   46 17 S19W23 0170   DAC    
S2959 2013.12.27   1 1 N18E66 0004   AXX    
S2960 2013.12.27   2 2 S12E07 0008   BXO   maybe two groups
Total spot count: 37 152 84  
Sunspot number: 107 292 184  (total spot count + 10 * number of spotted regions)
Weighted SN: 62 180 112  (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): 64 102 101 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
2013.12 148.8 (1) 104.0 (2A) / 119.4 (2B) / 89.9 (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.