Last major update issued on December 20, 2013 at 03:55 UTC.
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[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)]
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[POES auroral activity level since October
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[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet on December 19. Solar wind speed at SOHO ranged between 309 and 446 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 153.4 (increasing 10.6 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 137.4. The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.9). Three hour interval K indices: 11001221 (planetary), 11101211 (Boulder).
The background x-ray flux was at the class B8 level.
At the time of counting spots (see image time) spots were observed in 12 active regions in 2K resolution (SN: 252) and 9 active regions in 1K resolution (SN: 156) SDO images on the visible solar disk.
Region 11917 [S17W84] rotated partly out of view.
Region 11918 [S09W67] decayed quickly with only a few penumbra spots remaining at the end of the day.
Region 11920 [N12W61] was quiet and stable.
Region 11921 [N07W57] was quiet and stable.
Region 11925 [S07W25] was quiet and stable.
Region 11928 [S16W20] developed slowly and was mostly quiet. There's a weak magnetic delta structure in a central penumbra. C and minor M class flares are possible.
Region 11929 [S11E39] developed slowly and quietly.
Region 11930 [S10E22] gained penumbral area and lost a few spots.
Region 11931 [S14E68] rotated fully into view. Further M class flaring is possible. C5+ flare: M3.5 at 23:19 UTC.
Region 11932 [N04E17] emerged on December 18 and was numbered by SWPC the next day.
Spotted regions not numbered by SWPC:
S2918 [S13W37] developed quickly and could produce C flares.
New region S2931 [S06W45] emerged with a penumbra spot.
December 17-19: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
Coronal hole history (since October
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.
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.
The geomagnetic field is expected to be quiet on December 20-23.
|Coronal holes (1)||Coronal mass ejection (2)||M and X class flares (3)|
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.
(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.
|Active region||Date numbered
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlay
|Total spot count:||48||132||66|
|Sunspot number:||138||252||156||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||83||188||117||(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):||83||88||86||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
|2011.11||153.5 (cycle peak)||96.7 (cycle peak)||61.1 (+1.2)||5.55|
possible cycle 24 max
|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||155.0 (1)||76.0 (2A) / 124.1 (2B) / 81.3 (2C)||(61.7 projected, -1.3)||(5.4)|
1) Running average based on the daily 20:00 UTC observed solar flux value at
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.