Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 26, 2013 at 06:15 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 quiet on December 25. Solar wind speed at SOHO ranged between 270 and 333 km/s under the influence of a weak, low speed disturbance.

Solar flux measured at 20h UTC on 2.8 GHz was 122.7 (decreasing 10.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 138.8. The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.1). Three hour interval K indices: 21122110 (planetary), 21233310 (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 12 active regions in 2K resolution (SN: 204) and 9 active regions in 1K resolution (SN: 136) SDO images on the visible solar disk.

Region 11929 [S13W42] was quiet and stable.
Region 11930 [S08W63] decayed losing all trailing spots.
Region 11931 [S16W07] displayed no major changes and was mostly quiet.

Region 11935 [S08E21] was quiet and stable.
Region 11936 [S18E47] produced a few low level C flares. The region is developing centrally and could produce C flares and maybe a minor M class flare.

Spotted regions not numbered by SWPC:
S2944 [S05W17] decayed slowly and quietly.
S2947 [S20E62] was quiet and stable.
S2948 [S29E39] was quiet and stable.
S2949 [N07E63] was quiet and stable.
New region S2952 [S13E73] rotated into view.
New region S2953 [S24E21] emerged with penumbra spots.
New region S2954 [N21E09] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

December 23-25: 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 poor. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet on December 26-29.

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
  2 1 S12W44 0005   BXO  
11930 2013.12.17
2013.12.18
4 2 1 S09W59 0030 CAO HSX

area: 0060

location: S08W63

11931 2013.12.18 5 45 28 S16W16 0230 HAX FKI images/AR_11931_20131225_2345.png images\AR_11931_20131224_2345.png beta-gamma

area: 0650

location: S16W08

11932 2013.12.18
2013.12.19
      N04W71           plage
11934 2013.12.20 14     S15E01 0170 CAO       the spots are magnetically part of AR 11931
S2937 2013.12.21       N18W58           plage
11936 2013.12.22
2013.12.23
7 19 10 S17E43 0050 CAO EAI beta-gamma

area: 0140

location: S18E47

11935 2013.12.22
2013.12.23
1 2 1 S07E20 0010 AXX HRX area: 0022
S2941 2013.12.22       N14E13         plage
S2943 2013.12.22       N08E03         plage
S2944 2013.12.23   2   S05W17 0004   BXO  
S2945 2013.12.23       N29W03           plage
S2947 2013.12.24   3 1 S20E62 0009   AXX  
S2948 2013.12.24   1 1 S29E39 0005   AXX  
S2949 2013.12.24   1   N07E63 0002   AXX  
S2950 2013.12.24       N13E30         plage
S2951 2013.12.24       N09W09         plage
S2952 2013.12.25   4 2 S13E73 0035   DRO    
S2953 2013.12.25   2 1 S24E21 0005   BXO    
S2954 2013.12.25   1   N21E09 0002   AXX    
Total spot count: 31 84 46  
Sunspot number: 81 204 136  (total spot count + 10 * number of spotted regions)
Weighted SN: 51 110 72  (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): 49 71 75 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
2013.12 150.5 (1) 97.5 (2A) / 120.8 (2B) / 87.4 (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.