Last major update issued on December 28, 2011 at 06:45 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update December 1, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update December 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update December 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update December 2, 2011)]
[POES auroral activity level since October
2009 - updated December 27, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2116 [October-November 2011] - 2117 [November-December 2011] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was very quiet on December 27. Solar wind speed ranged between 271 and 344 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 140.3 (decreasing 3.7 over the last solar rotation). The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 0.6). Three hour interval K indices: 00000001 (planetary), 00001221 (Boulder).
The background x-ray flux is at the class B9 level.
At midnight UTC the visible solar disk had 12 spotted regions (in 2K resolution SDO images).
Region 11380 [S20W56] is a complex region with significant polarity
intermixing. There's at least one minor
magnetic delta structure. M class flares are possible. Note that SWPC has this as
region 11387. Flares: C3.8 at 08:22, C4.0 at
09:23, C6.2 at 12:07, C2.5 at 18:36 UTC.
Region 11383 [N05W38] decayed slowly and could soon become spotless.
Region 11384 [N13W28] decayed in the trailing spot section while the large penumbra took on an asymmetrical shape.
Region 11385 [S32W49] lost the leader spots and could soon become spotless.
Region 11386 [S16E18] displayed no major changes. Note that SWPC includes regions S1392 and S1395 in this region. Flare: C8.9/1F at 04:22 UTC. This event was associated with at least a partial halo CME where quite a bit of material was hurled northwards.
New region 11388 [S23E69] rotated into view at the southeast limb on December 26 and got an SWPC number the next day.
Spotted regions not reported (or interpreted differently) by NOAA/SWPC:
[S1392] rotated into view at the southeast limb on December 23. Location at midnight: S18E23
[S1394] emerged in the northeast quadrant on December 24. Location at midnight: N26W13
[S1395] emerged in the southeast quadrant on December 25. Location at midnight: S18E27
[S1397] emerged in the southwest quadrant on December 26. Location at midnight: S20W78
[S1399] rotated into view at the southeast limb on December 27. Location at midnight: S19E84. Flare: C6.7 at 22:26 UTC.
[S1400] emerged in the northeast quadrant on December 27. Location at midnight: N17E42
December 25: A partial halo CME was observed early in the day in LASCO images
in association with a filament eruption in the central northern hemisphere.
There's a 20-30% chance of a flank impact from this CME sometime on December 28.
A CME was observed in STEREO images after the M4 event in region 11380. This CME
could reach Earth sometime between late on December 27 and late on December 28
and cause unsettled to major storm conditions.
December 26: At least a partial halo CME was observed after a filament eruption across the central meridian near region 11384. This CME could reach Earth on December 29.
December 27: At least a partial halo CME was associated with the C8 flare in region 11386 early in the day. This CME is fairly slow and could reach Earth on December 30.
Coronal hole history (since late October
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A large extension (CH490) of the southern polar coronal hole will rotate into a potentially geoeffective position on December 26-29.
The above coronal hole map is based on a new method where coronal holes are detected automatically. The method may need some fine tuning, however, 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 the new method, the extent and intensity of both holes 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 fair to good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet to minor storm on December 28-31 due to CME and coronal hole effects, occasional major storm intervals are possible.
|Coronal holes (1)||Coronal mass ejections (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
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
SWPC has a data consistency problem with regions 11381/11382
SWPC lost track of this region and assigned a new number 11387. Strangely they are reporting spots for this region at a location where there are no spots
SWPC includes regions S1392, S1395
|11387||2011.12.25||17||S21W57||0290||DKI||see region 11380|
|Total spot count:||46||60|
|Sunspot number:||126||180||(total spot count + 10 * number of spotted regions)|
|Weighted penumbral SN:||81||100||(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):||76||81||k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1) for STAR SDO|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|2010.10||81.6||23.5||23.2 (+3.6)||6.07 / 6.27|
|2010.11||82.5||21.5||26.5 (+3.3)||4.80 / 5.50|
|2010.12||84.2||14.4||28.8 (+2.3)||3.41 / 4.35|
|2011.01||83.6||19.1||31.0 (+2.2)||4.32 / 5.51|
|2011.02||94.6||29.4||33.4 (+2.4)||5.41 / 6.44|
|2011.03||115.0||56.2||36.9 (+3.5)||7.79 / 8.18|
|2011.04||112.6||54.4||41.8 (+4.9)||9.71 / 8.83|
|2011.05||95.8||41.6||47.6 (+5.8)||9.18 / 8.94|
|2011.06||95.8||37.0||(53.7 projected, +6.1)||8.96 / 8.06|
|2011.07||94.2||43.9||(60.0 projected, +6.3)||9.14 / 8.16|
|2011.08||101.7||50.6||(65.5 projected, +5.5)||8.16 / 7.26|
|2011.09||133.8||78.0||(68.8 projected, +3.3)||12.80 / 12.27|
|2011.10||137.3||88.0||(72.3 projected, +3.5)||7.52|
|2011.11||153.5||96.7||(76.6 projected, +4.3)||4.58|
|2011.12||141.3 (1)||92.8 (2A) / 106.5 (2B)||(82.1 projected, +5.5)||(3.10)|
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) Month average to date.
3) Running average based on the preliminary daily SWPC ap indices. Values in red are based on the official NGDC 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.