Last major update issued on December 13, 2013 at 05:50 UTC.
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[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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[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was very quiet on December 12. Solar wind speed at SOHO ranged between 270 and 362 km/.
Solar flux measured at 20h UTC on 2.8 GHz was 164.8 (decreasing 13.1 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 133.3. The Potsdam WDC planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.1). Three hour interval K indices: 00000001 (planetary), 01010101 (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 14 active regions in 2K resolution (SN: 307) and 11 active regions in 1K resolution (SN: 196) SDO images on the visible solar disk.
Region 11912 [S22W62] regained a trailing penumbra
spot. The region prodoced a long duration C4.6 event peaking at 03:23 UTC. This
event was associated with a partial halo CME.
Region 11916 [S13W84] rotated partly out of view and was quiet.
Region 11917 [S16E03] produced a C3.4 long duration event peaking at 06:59 UTC. This event triggered a filament eruption to the south of the region.
Region 11918 [S10E24] developed slowly and quietly.
Region 11919 [S05W67] decayed slowly and quietly.
Region 11920 [N07E36] gained spots and was mostly quiet. C5+ flare: C5.9 at 22:14 UTC
Region 11922 [N09W46] decayed slowly and quietly.
Region 11923 [N17E03] developed slowly and quietly.
Region 11924 [S12W73] was quiet and stable.
Spotted regions not numbered by SWPC:
S2892 [S14W23] decayed slowly and quietly.
S2910 [S07E70] developed slowly and quietly. The region has minor polarity intermixing.
S2911 [N18E14] was quiet and stable.
New region S2912 [S26E23] emerged with penumbra spots in an old plage area.
New region S2913 [N03W22] emerged with a penumbra spot.
December 10-11: No obviously Earth directed CMEs were observed in LASCO
December 12: A partial halo CME (full halo in STEREO-B) was observed after the C4 event in AR 11912. This CME could have an Earth directed extension. A filament eruption the the south of 11917 was associated with a partial halo CME, possibly with an Earth directed extension.
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
A large northern hemisphere coronal hole (CH597) was in an Earth facing position on December 11.
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.
The geomagnetic field is expected to be initially quiet on December 13. A high speed stream from CH597 could cause unsettled and active intervals from the latter half of December 13 until December 15.
|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
|11921||2013.12.09||2||N08E37||0360||HKX||magnetically part of AR 11920|
|Total spot count:||56||167||86|
|Sunspot number:||156||307||196||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||99||209||128||(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):||94||107||108||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||153.2 (1)||46.3 (2A) / 119.5 (2B) / 84.9 (2C)||(61.7 projected, -1.3)||(5.6)|
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.