Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 7, 2013 at 06:05 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 quiet on December 6. Solar wind speed at SOHO ranged between 323 and 378 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 150.5 (increasing 2.4 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 128.9. The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.1). Three hour interval K indices: 11111112 (planetary), 11011121 (Boulder).

The background x-ray flux was at the class C1 level.

At the time of counting spots (see image time) spots were observed in 9 active regions in 2K resolution (SN: 195) and 8 active regions in 1K resolution (SN: 139) SDO images on the visible solar disk.

Region 11908 [S24W79] decayed slowly and quietly.
Region 11909 [S18W48] decayed slowly and quietly.
Region 11912 [S20E15] was quiet and stable.
Region 11915 [S29W48] decayed slowly and quietly.
Region 11916 [S12W12] developed and could produce C and minor M class flares. The region has polarity intermixing.

Spotted regions not numbered by SWPC:
S2876 [S13W26] was quiet and stable.
S2892 [S11E51] reemerged with penumbra spots.
New region S2894 [S16E81] rotated partly into view. The single penumbra may contain a magnetic delta structure, however, the region will have to rotate into better view to determine this.
New region S2895 [N33W32] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

December 4: A filament eruption across the central meridian in the northern hemisphere may have been associated with a CME, however, no LASCO imagery has become available over the last day. STEREO indicates a small CME was launched.
December 5: A filament eruption was observed near AR 11909 starting at 20:41 UTC in SDO/AIA imagery. STEREO imagery indicate that there was a CME associated with this event and that it could have an Earth directed component.
December 6: 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 trans equatorial coronal hole (CH596) was in an Earth facing position on December 3-4.

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 to active on December 7 due to effects from CH596. Quiet to unsettled conditions are likely on December 8-9.

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
11908 2013.11.26
2013.11.27
2 1 1 S25W79 0040 HSX HRX  
11909 2013.11.26
2013.11.27
10 18 9 S17W50 0140 DSO ESO

location: S18W48

S2866 2013.11.28       S30W48           plage
11911 2013.11.29
2013.11.28
1     S11W64 0010 AXX    

spotless

11914 2013.11.29
2013.12.02
      S18W75         plage
S2871 2013.11.30       N21W12           plage
S2876 2013.12.01   6 2 S13W26 0014   AXX  
11912 2013.12.01
2013.12.02
1 17 7 S21E17 0130 CAO CSO area: 0180

location: S20E15

S2878 2013.12.01       S27W21           plage
11915 2013.12.01
2013.12.03
10 10 7 S30W48 0030 DRO DRI area: 0050
S2880 2013.12.02       S13W49           plage
S2881 2013.12.02       N10W40           plage
S2882 2013.12.02       N24W32           plage
S2883 2013.12.02       S06W50           plage
S2886 2013.12.03       S27W23         plage
S2887 2013.12.03       N08W14           plage
11916 2013.12.04 21 45 30 S13W10 0200 DAC DAC beta-gamma

area: 0350

location: S12W12

S2890 2013.12.04       S10W35         plage
S2892 2013.12.04   5   S11E62 0012   BXO    
S2894 2013.12.06   2 2 S16E81 0100   HAX   possible magnetic delta
S2895 2013.12.06   1 1 N33W32 0004   AXX    
Total spot count: 45 105 59  
Sunspot number: 105 195 139  (total spot count + 10 * number of spotted regions)
Weighted SN: 68 131 85  (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): 63 68 76 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)
possibe 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 (61.5 projected, +1.6) 12.60
2013.07 115.5 57.0 (62.1 projected, +0.6) 9.47
2013.08 114.6 66.0 (62.3 projected, +0.2) 8.27
2013.09 102.6 36.9 (61.2 projected, -1.1) 5.23
2013.10  132.1 85.6 (59.0 projected, -2.2) 7.71
2013.11  148.3 77.6 (57.3 projected, -1.7) 5.68
2013.12 139.1 (1) 20.4 (2A) / 105.2 (2B) / 81.0 (2C) (56.1 projected, -1.2) (4.7)

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.