Last major update issued on December 20, 2013 at 03:50 UTC.
[Solar and geomagnetic data - last month (updated
[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)]
The geomagnetic field was quiet to unsettled on December 20. Solar wind speed at SOHO ranged between 337 and 418 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 149.2 (increasing 13.6 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 137.8. The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.3). Three hour interval K indices: 13010111 (planetary), 13121211 (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 11 active regions in 2K resolution (SN: 289) and 9 active regions in 1K resolution (SN: 176) SDO images on the visible solar disk.
Region 11920 [N13W76] decayed slowly and quietly.
Region 11921 [N07W68] decayed slowly and quietly.
Region 11925 [S07W39] was quiet and stable.
Region 11928 [S16W33] developed slowly and has an elongated magnetic delta structure in a central penumbra. C and M class flares are likely. C5+ flares: C8.5 at 15:33, C5.4 at 16:30 UTC.
Region 11929 [S12E26] developed slowly in the leading polarity with decay observed in the trailing polarity area.
Region 11930 [S09E07] developed slowly and quietly.
Region 11931 [S14E56] has a positive polarity area embedded within the trailing negative polarity. This significant polarity intermixing could cause further M class flaring. C5+ flare: M1.6 at 11:57 UTC.
Region 11932 [N03E05] decayed slowly and quietly.
New region 11933 [S12W52] was first observed with spots on December 14. New flux emerged on December 19 and the region matured quickly on December 20.
Spotted regions not numbered by SWPC:
New region S2934 [S25W76] emerged with a penumbra spot early in the day.
New region S2935 [N17E08] emerged with a penumbra spot.
December 18-20: 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 21-23.
|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
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.
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
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlay
|11934||2013.12.20||3||S15E65||0080||CAO||the spots are part of AR 11931|
|Total spot count:||47||179||86|
|Sunspot number:||137||289||176||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||87||222||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):||82||101||97||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||154.7 (1)||80.5 (2A) / 124.7 (2B) / 82.4 (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.