Last major update issued on December 7, 2011 at 03:55 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2115 [September-October 2011] - 2116 [October-November 2011] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was very quiet on December 6. Solar wind speed ranged between 270 and 356 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 151.1 (decreasing 29.1 over the last solar rotation). The planetary A index was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.3). Three hour interval K indices: 00001100 (planetary), 00001110 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight UTC the visible solar disk had 16 spotted regions (in 2K resolution SDO images).
Region 11362 [N07W45] decayed slowly and has weak polarity intermixing.
Region 11363 [S17W23] was quiet and stable.
Region 11364 [N20W15] was quiet and stable.
Region 11365 [N20W37] decayed slowly and quietly.
Region 11366 [N18E26] was quiet and stable.
Region 11367 [S17E08] decayed slowly and quietly.
Region 11368 [S15E41] decayed slowly and quietly.
Region 11369 [N22E32] decayed slowly and quietly.
Spotted regions not reported by NOAA/SWPC:
[S1342] rotated into view at the southeast limb on Nov.28. The region developed quickly on Dec.1-3 while decay was observed in the trailing and central spot sections on Dec.4-6. There's minor polarity intermixing. Location at midnight: S22W19.
[S1343] emerged in the southeast quadrant on November 29, became spotless and reemerged on Dec.6. Location at midnight: S12W43
[S1349] was split off from 11366 on December 4. Location at midnight: N27E26
[S1351] emerged in the northeast quadrant on December 4, became spotless and reemerged on Dec.6. Location at midnight: N10E28
[S1353] emerged in the northeast quadrant on December 4. Location at midnight: N13E36
[S1354] emerged in the southeast quadrant on December 5 and developed on Dec.6. Location at midnight: S25E11
[S1355] emerged in the northeast quadrant on December 5. Location at midnight: N24E07
[S1357] emerged in the northeast quadrant on December 6. Location at midnight: N09E46
December 4-6: No obviously Earth directed CMEs observed.
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 small coronal hole (CH487) in the northern hemisphere could rotate into an Earth facing position on December 7-8.
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. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on December 7-10. On December 11-12 there's a chance of a few unsettled and active intervals due to effects from CH487.
|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 includes S1342 in this region
|Total spot count:||53||89|
|Sunspot number:||143||249||(total spot count + 10 * number of spotted regions)|
|Weighted penumbral SN:||83||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):||86||112||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||157.1 (1)||26.3 (2A) / 135.8 (2B)||(82.1 projected, +5.5)||(4.65)|
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.