Last major update issued on October 12, 2011 at 04:20 UTC. Minor update posted at 15:10 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2113 [July-August 2011] - 2114 [August-September 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was quiet on October 11. Solar wind speed ranged between 304 and 372 km/s.
Solar flux measured at 23h UTC on 2.8 GHz was 130.1 (decreasing 12.5 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.9). Three hour interval K indices: 00102211 (planetary), 00101321 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight UTC the visible solar disk had 10 spotted regions (in 2K resolution SDO images).
Region 11309 [N23W49] decayed slowly and quietly.
Region 11311 [S12W77] rotated quietly to the southwest limb.
Region 11312 [N23W15] was quiet and stable.
Region 11313 [S14W12] has minor polarity intermixing, however, opposite polarity spots are not closely spaced and the region was quiet.
Region 11314 [N27E48] was quiet and mostly unchanged. There's a small chance of a major flare.
Region 11315 [N20W05] decayed quickly and was quiet.
New region 11316 [S12E57] emerged near the southeast limb on October 10 and was numbered the next day by SWPC. The region developed fairly quickly and is currently the most complex region on the visible disk. There's a weak magnetic delta structure at the eastern edge of the main penumbra and some polarity intermixing elsewhere in this fairly compact region. Further C flares are possible and if the region develops further there'll be a chance of minor M class flares. Flare: C1.1 at 23:23 UTC.
New region 11317 [S26E68] rotated into view at the southeast limb on October 10 and was assigned a number by SWPC the following day.
Spotted regions not reported by NOAA/SWPC:
[S1267] emerged near the northeast limb on October 10 and developed on October 11. The region has polarity intermixing. Location at midnight: N10E57
[S1270] emerged in the northeast quadrant on October 11. Polarities are intermixed. Location at midnight: N22E10
Minor update added at 15:10 UTC on October 12: Regions 11316 and S1267 have developed further with both becoming capable of producing minor M class flares. Flare activity has increased significantly today because of the development in these two regions. The latest high resolution CHARMAP.
October 9-11: 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 trans equatorial coronal hole (CH479) will rotate into an Earth facing position on October 12-13.
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 poor to fair. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet on October 12-14. Quiet to active with a chance of minor storm intervals is possible on October 15-16 due to effects from CH479.
|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 polarity overlay
|1||1||S26E68||0090||HSX||HSX||formerly region S1265|
formerly region S1266
|Total spot count:||33||76|
|Sunspot number:||113||176||(total spot count + 10 * number of spotted regions)|
|Classification adjusted SN:||78||122||(Sum of total spot count + classification adjustment for each AR. Classification adjustment: X=0, R=3, A/S=5, H/K=10)|
|Relative sunspot number (Wolf number):||68||58||k * (sunspot number). k = 0.6 for SWPC. k = 0.33 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)|
|2010.07||79.8||16.1||16.7 (+0.3)||6.31 / 5.15|
|2010.08||79.2||19.6||17.4 (+0.7)||8.49 / 7.77|
|2010.09||81.1||25.2||19.6 (+2.2)||5.33 / 5.45|
|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||(41.1 predicted, +4.2)||9.71 / 8.83|
|2011.05||95.8||41.6||(45.2 predicted, +4.1)||9.18 / 8.94|
|2011.06||95.8||37.0||(49.2 predicted, +4.0)||8.96|
|2011.07||94.2||43.9||(53.1 predicted, +3.9)||9.14|
|2011.08||101.7||50.6||(57.2 predicted, +4.1)||8.16|
|2011.09||133.8||78.0||(60.3 predicted, +3.1)||12.80|
|2011.10||126.9 (1)||33.3 (2A) / 93.8 (2B)||(61.8 predicted, +1.5)||(8.42)|
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.