Last major update issued on December 29, 2013 at 04:15 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]
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[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was very quiet on December 28. Solar wind speed at SOHO ranged between 271 and 397 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 134.5 (increasing 4.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 139.5. The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.1). Three hour interval K indices: 10001111 (planetary), 00101221 (Boulder).
The background x-ray flux was at the class B6 level.
At the time of counting spots (see image time) spots were observed in 11 active regions in 2K resolution (SN: 290) and 9 active regions in 1K resolution (SN: 173) SDO images on the visible solar disk.
Region 11931 [S14W57] was quiet and stable.
Region 11936 [S17E07] developed further and has a small magnetic delta structure. C and minor M class flares are possible. C5+ flare: C9.3 at 18:02 UTC
Region 11937 [S12E34] decayed slowly and quietly.
Region 11938 [S12E51] was quiet and stable
Spotted regions not numbered by SWPC:
S2944 [S07W57] reemerged with several spots.
S2948 [S27W00] was quiet and stable.
S2958 [S17W40] developed slowly as the leading polarity area expanded to include parts of a neighboring region. C and M class flares are possible.
S2959 [N18E53] developed slowly and quietly.
New region S2961 [S14E13] emerged early in the day with a penumbra spot.
New region S2962 [S02W46] emerged near the equator with penumbra spots.
New region S2964 [N05W50] emerged with penumbra spots.
A flare a few days behind the west limb was associated with a very wide CME and a small proton event which began late in the day.
December 26-28: 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
A recurrent trans equatorial coronal hole (CH598) will rotate into an Earth facing position on December 29-31.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is fair to good (very poor over high latitudes due to a proton event). Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on December 29-31 and quiet to active on January 1-3 due to effects from CH598.
|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||15||S18W38||0160||ESI||see AR S2958|
|Total spot count:||45||180||83|
|Sunspot number:||95||290||173||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||65||211||114||(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):||57||102||95||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||148.3 (1)||107.1 (2A) / 118.5 (2B) / 91.0 (2C)||(61.7 projected, -1.3)||(4.6)|
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.