Last major update issued on December 21, 2012 at 04:35 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update December 1, 2012)] [Cycle 24 progress (last update December 2, 2012) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update December 1, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update December 1, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update December 7, 2012)]
[POES auroral activity level since October
2009 - updated October 7, 2012]
[Solar polar fields vs solar cycles - updated December 9, 2012]
The geomagnetic field was quiet to unsettled on December 20. Solar wind speed at SOHO ranged between 429 and 550 km/s under the influence of a high speed coronal hole stream.
Solar flux measured at 20h UTC on 2.8 GHz was 114.1 (decreasing 12.6 over the last solar rotation). The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.4). Three hour interval K indices: 11223322 (planetary), 12222321 (Boulder).
The background x-ray flux was at the class B2 level.
At midnight UTC the visible solar disk had 6 spotted active regions (in 2K resolution SDO images).
Region 11633 [S07E02] was quiet and stable.
Region 11634 [S12E04] was quiet and stable.
Region 11635 [N11E49] developed adding spots and penumbral area. The large penumbra split into two smaller penumbrae.
Spotted regions not numbered by NOAA/SWPC:
S2116 [N10W27] reemerged with tiny spots.
New region S2119 [N07E59] emerged to the southeast of AR 11635.
New region S2120 [S31W22] emerged with tiny spots in an old plage area.
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
A recurrent trans equatorial coronal hole (CH548) will likely rotate into an Earth facing position on December 23. CH548 did not cause any significant disturbance during the previous rotation.
The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using this method, the extent and intensity of both CHs are consistent with other data sources.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair.
The geomagnetic field is expected to be quiet on December 21-25. On December 26-27 there's a chance of unsettled intervals due to weak coronal hole effects.
|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 higher resolution image) 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 (blue-green) 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
|Total spot count:||23||53||28|
|Sunspot number:||53||113||68||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||48||73||48||(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):||32||40||37||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 max)||96.7 (cycle max)||61.1 (+1.2)||5.55|
possible cycle 24 max
|2012.06||119.6||64.5||(59.5 projected, -2.2)||10.08|
|2012.07||133.9||66.5||(58.8 projected, -0.7)||13.90|
|2012.08||115.4||63.1||(60.1 projected, +1.3)||7.96|
|2012.09||122.9||61.5||(61.1 projected, +1.0)||8.07|
|2012.10||123.3||53.3||(60.7 projected, -0.4)||9.97|
|2012.11||121.3||61.4||(60.0 projected, -0.7)||7.08|
|2012.12||107.2 (1)||37.5 (2A) / 58.2 (2B) / 43.1 (2C)||(59.3 projected, -0.7)||(4.08)|
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 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.