Last major update issued on February 13, 2012 at 06:00 UTC.
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The geomagnetic field was quiet on February 12. Solar wind speed ranged between 284 and 351 km/s. The arrival of a low speed stream (near 06h UTC at ACE) associated with CH500 caused only a minor increase in solar wind speed and the total field of the IMF.
Solar flux measured at 20h UTC on 2.8 GHz was 110.4 (decreasing 29.3 over the last solar rotation). The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.0). Three hour interval K indices: 12001111 (planetary), 02111211 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight UTC the visible solar disk had 10 spotted regions (in 2K resolution SDO images).
Region 11416 [S18W16] decayed slowly and quietly.
Region 11417 [N17E34] was quiet and stable.
New region 11418 [S23E13] emerged in the southeast quadrant on February 10 and was numbered by SWPC two days later.
New region 11419 [N28E73] rotated into view at the northeast limb. Flares: C1.3 at 04:46, C1.6 at 06:53, C3.9 at 14:43 UTC.
New region 11420 [N11E78] rotated into view at the northeast limb.
Spotted regions not reported by NOAA/SWPC:
[S1461] reemerged on Feb.12 with a couple of spots. Location at midnight: N08W63
[S1466] reemerged on Feb.12. Location at midnight: N17E11
[S1474] emerged in the northwest quadrant on February 12. Location at midnight: N04W25
[S1475] emerged in the southeast quadrant on February 12. Location at midnight: S23E23
[S1476] emerged in the northeast quadrant on February 12. Location at midnight: N10E06
February 11-12: No obviously Earth directed CMEs were observed in LASCO and
February 10: A filament eruption in the northeast quadrant in the evening was associated with a partial halo CME. A flank impact is possible on February 13 or 14.
February 9: A filament eruption near region 11417 late in the day produced a large partial halo CME with nearly all material observed off the east limb. There were faint traces of ejecta over parts of the northwest limb. While the core of the CME will not reach Earth there's a chance of a weak flanking impact on February 13.
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
An expanding trans equatorial coronal hole (CH501) will likely rotate into an Earth facing position on February 15-16.
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 to fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet to unsettled on February 13 due to weak coronal hole effects. Quiet to active conditions are possible on February 14 due to possible CME effects. Quiet conditions are likely on February 15-17. A high speed stream from CH501 could cause quiet to active conditions on February 18-19.
|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
|Total spot count:||30||42||26|
|Sunspot number:||80||142||96||(total spot count + 10 * number of spotted regions)|
|Weighted penumbral SN:||55||65||49||(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):||48||64||k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1, 2011) for STAR SDO 2K|
|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)|
|2010.11||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||53.2 (+5.6)||8.96 / 8.06|
|2011.07||94.2||43.9||57.2 (+4.0)||9.14 / 8.16|
|2011.08||101.7||50.6||(60.4 projected, +3.2)||8.16 / 7.26|
|2011.09||133.8||78.0||(63.1 projected, +2.7)||12.80 / 12.27|
|2011.10||137.3||88.0||(65.8 projected, +2.7)||7.52 / 8.28|
|2011.11||153.5||96.7||(69.1 projected, +3.3)||4.58 / 5.55|
|2011.12||141.3||73.0||(73.9 projected, +4.8)||3.32|
|2012.01||132.5||58.3||(79.3 projected, +5.4)||6.59|
|2012.02||108.0 (1)||19.7 (2A) / 47.6 (2B)||(82.4 projected, +3.1)||(6.83)|
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.