Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 25, 2013 at 05:50 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 24. Solar wind speed at SOHO ranged between 272 and 341 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 128.3 (decreasing 0.7 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 138.7. The Potsdam WDC planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.0). Three hour interval K indices: 00000001 (planetary), 00001222 (Boulder).

The background x-ray flux was at the class B4 level.

At the time of counting spots (see image time) spots were observed in 14 active regions in 2K resolution (SN: 250) and 10 active regions in 1K resolution (SN: 150) SDO images on the visible solar disk.

Region 11928 [S17W83] decayed further and rotated partly out of view.
Region 11929 [S13W25] was quiet and stable.
Region 11930 [S09W47] was quiet and stable.
Region 11931 [S15E06] decayed slowly in the trailing spot section. C and M class flaring is possible.

Region 11935 [S07E35] was quiet and stable.
Region 11936 [S18E59] was quiet and stable. C flares are possible.

Spotted regions not numbered by SWPC:
S2941 [N14E26] reemerged with a penumbra spot.
S2943 [N08E16] was quiet and stable.
S2944 [S08W04] decayed slowly and quietly.
New region S2947 [S20E76] rotated into view.
New region S2948 [S28E52] emerged with a penumbra spot.
New region S2949 [N07E76] emerged with a penumbra spot.
New region S2950 [N13E43] emerged with a penumbra spot.
New region S2951 [N09E04] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

December 22-24: 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 likely rotate into an Earth facing position on December 29-30.

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 25-27 with a chance of a few unsettled intervals on December 25.

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
11928 2013.12.16
2013.12.17
8 4 1 S16W87 0130 DAI BXO  
11929 2013.12.16
2013.12.18
  7 4 S12W30 0015   BXO  
11930 2013.12.17
2013.12.18
5 13 5 S09W46 0070 CAO DAI

area: 0100

11931 2013.12.18 1 54 25 S15W04 0210 HAX FHI images\AR_11931_20131224_2345.png beta-gamma

area: 0650

location: S15E06

11932 2013.12.18
2013.12.19
      N04W56         plage
11934 2013.12.20 16     S16E14 0200 DAO       the spots are magnetically part of AR 11931
S2935 2013.12.20       N17W44           plage
S2937 2013.12.21       N18W45         plage
11936 2013.12.22
2013.12.23
5 16 7 S16E55 0050 CAO EAI beta-gamma

area: 0150

location: S18E59

11935 2013.12.22
2013.12.23
1 2 1 S06E33 0010 AXX HRX area: 0025
S2941 2013.12.22   1   N14E26 0002   AXX    
S2943 2013.12.22   1 1 N08E16 0002   AXX  
S2944 2013.12.23   7 4 S08W04 0018   BXO  
S2945 2013.12.23       N29E10         plage
S2947 2013.12.24   1 1 S20E76 0012   HRX    
S2948 2013.12.24   1   S28E52 0003   AXX    
S2949 2013.12.24   1   N07E76 0003   AXX    
S2950 2013.12.24   1   N13E43 0002   AXX    
S2951 2013.12.24   1 1 N09E04 0004   AXX    
Total spot count: 36 110 50  
Sunspot number: 96 250 150  (total spot count + 10 * number of spotted regions)
Weighted SN: 61 136 76  (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): 58 88 83 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
2013.12 151.7 (1) 94.8 (2A) / 122.5 (2B) / 86.0 (2C) (61.7 projected, -1.3) (4.9)

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.