Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 19, 2013 at 05:10 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 18. Solar wind speed at SOHO ranged between 338 and 390 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 156.0 (increasing 14.8 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 137.0. The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.3). Three hour interval K indices: 11110111 (planetary), 01211212 (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 12 active regions in 2K resolution (SN: 269) and 11 active regions in 1K resolution (SN: 185) SDO images on the visible solar disk.

Region 11917 [S17W74] was quiet and stable.
Region 11918 [S10W55] decayed quickly and quietly.
Region 11920 [N12W47] gained trailing spot umbrae and was quiet.
Region 11921 [N07W42] was split off from AR 11920 as the regions now appear to have separated magnetically.
Region 11925 [S08W13] was quiet and stable.
Region 11928 [S16W05] developed further gaining penumbral area. The magnetic delta structures disappeared, however, there is still polarity intermixing. C and minor M class flares are possible.
New region 11929 [S11E56] rotated into view on December 16 and was numbereb by SWPC 2 days later.
New region 11930 [S10E37] emerged on December 17 getting its NOAA number the next day. The region is developing and could produce C flares.
New region 11931 [S15E75] rotated into view early in the day with one spot.

Spotted regions not numbered by SWPC:
S2918 [S18W22] was quiet and stable.
New region S2929 [N04E32] emerged during the latter part of the day has umbrae in both polarities.
New region S2930 [S37W10] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

December 16-18: 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

No obvious coronal holes are currently in or near Earth facing positions.

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

Forecast

The geomagnetic field is expected to be quiet on December 19-21.

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
11917 2013.12.06
2013.12.07
4 12 6 S16W77 0420 DKI DKO beta-gamma

area: 0350

11923 2013.12.07
2013.12.10
      N01W79           real location: N17W77
11918 2013.12.08 1 12 4 S10W55 0050 HAX CRO

 

11920 2013.12.08
2013.12.09
1 8 3 N12W48 0050 HSX DSO

location: N12W47

area: 0100

11921 2013.12.09 2 7 4 N06W43 0220 DSO CHO   area: 0420
11925 2013.12.11
2013.12.13
  8 2 S07W09 0018   BXO location: S08W13
S2912 2013.12.12       S22W55           plage
11926 2013.12.14       N10W58           plage
S2918 2013.12.14   5 1 S18W22 0013   AXX  
S2919 2013.12.14       N33W44           plage
S2921 2013.12.15       N21W19           plage
11928 2013.12.16
2013.12.17
21 55 38 S15W05 0240 DAI EKC beta-gamma

area: 0550

11929 2013.12.16
2013.12.18
1 9 3 S11E55 0010 HRX CRO area: 0035
S2924 2013.12.16       N10W25           plage
S2925 2013.12.16       N08W16         plage
11930 2013.12.17
2013.12.18
7 27 10 S09E35 0040 CAI DRI location: S10E37

area: 0130

11931 2013.12.18 1 1 1 S14E76 0100 HAX HSX   area: 0230
S2929 2013.12.18   4 3 N04E32 0030   DRO    
S2930 2013.12.18   1   S37W10 0001   AXX    
Total spot count: 38 149 75  
Sunspot number: 118 269 185  (total spot count + 10 * number of spotted regions)
Weighted SN: 81 203 129  (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): 71 94 102 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
2013.12 155.1 (1) 71.6 (2A) / 123.3 (2B) / 80.6 (2C) (61.7 projected, -1.3) (5.5)

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.