Last major update issued on December 16, 2010 at 05:15 UTC.
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The geomagnetic field was quiet to active on December 15. Solar wind speed ranged between 544 and 655 km/s under the influence of a high speed stream associated with CH430.
Solar flux measured at 20h UTC on 2.8 GHz was 86.9 (up 0.4 over the last solar rotation). The planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 8.9). Three hour interval K indices: 34111111 (planetary), 44222211 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight UTC the visible solar disk had 2 spotted regions.
Region 11133 decayed slowly and is rotating over the northwest limb.
Region 11135 produced a C flare and several B flares. While a single tiny spot was observed at the end of the day, early on December 16 the region is spotless. Flare: C5.3 at 06:39 UTC.
December 13 and 15: No obviously Earth directed CMEs were observed in LASCO or STEREO
December 14: The long duration event in the northwest quadrant on December 14 produced a partial halo CME. While the core of the CME is not Earth directed, there's a chance of a flank impact on December 18. However, as Earth may then be under the influence of a high speed stream from CH430, the CME could easily be absorbed into that stream and not cause any observable effects.
Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
An elongated, curved, trans equatorial coronal hole (CH430) will rotate into an Earth facing position on December 12-16.
Image courtesy of SDO (NASA) and the AIA consortium. Annotations are my own. The darkest areas on the solar disk are likely coronal holes.
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 poor to fair.
The geomagnetic field is expected to be quiet to unsettled on December 16-19 due to effects from CH430, occasional active 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 green.
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.
Compare to the previous day's image
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 (NASA) / AIA 4500
|Total spot count:||1||2|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
cycle 23 sunspot max.
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|2009.09||70.5||4.3||6.2 (+1.4)||3.88 / 3.61|
|2009.10||72.6||4.8||7.1 (+0.9)||3.66 / 3.56|
|2009.11||73.6||4.1||7.6 (+0.5)||2.45 / 2.63|
|2009.12||76.7||10.8||8.3 (+0.7)||1.41 / 1.92|
|2010.01||81.1||13.2||9.3 (+1.0)||2.93 / 3.07|
|2010.02||84.7||18.8||10.6 (+1.3)||4.15 / 4.61|
|2010.03||83.4||15.4||12.3 (+1.7)||4.58 / 4.65|
|2010.04||75.9||8.0||14.0 (+1.7)||10.22 / 10.24|
|2010.05||73.8||8.7||15.5 (+1.5)||9.18 / 8.15|
|2010.06||72.5||13.6||(16.9 predicted, +1.4)||8.17 / 6.85|
|2010.07||79.8||16.1||(18.4 predicted, +1.5)||6.31 / 5.15|
|2010.08||79.2||19.6||(19.6 predicted, +1.2)||8.49 / 7.77|
|2010.09||81.1||25.2||(20.8 predicted, +1.2)||5.33 / 5.45|
|2010.10||81.6||23.5||(23.2 predicted, +2.4)||6.07 / 6.27|
|2010.11||82.5||21.6||(26.1 predicted, +2.9)||4.80|
|2010.12||87.6 (1)||14.9 (2A) / 30.9 (2B)||(28.6 predicted, +2.5)||(3.19)|
1) Running average based on the
daily 20:00 UTC observed solar flux
value at 2800 MHz.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the 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.