Last major update issued on October 18, 2010 at 04:00 UTC.
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The geomagnetic field was quiet to active on October 17. Solar wind speed ranged between 315 and 411 km/s. The CME effects that began on October 15 unexpectedly intensified after 06h UTC.
Solar flux measured at 20h UTC on 2.8 GHz was 83.6 (up 1.0 over the last solar rotation). The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.1). Three hour interval K indices: 23431023 (planetary), 23532122 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight UTC the visible solar disk had 4 spotted regions.
Region 11112 lost several spots in the trailing spot section while
gaining a few leader spots. Flares:
impulsive C1.7 at 08:59 and C1.6 at 17:39 UTC.
Region 11113 was quiet and stable.
Region 11115 was quiet and stable.
New region 11116 emerged on October 16 and was numbered the next day by NOAA/SWPC. The region developed early in the day, then decayed.
October 15-17: No obviously Earth directed CMEs were seen in LASCO or STEREO images.
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
A recurrent coronal hole (CH425) in the northern hemisphere will rotate into an Earth facing position on October 15-18. CH425 has decayed significantly over the last solar rotation (and split into two smaller parts CH425A and CH425B due to an active region emerging) and it is uncertain if the coronal hole will produce any geomagnetic disturbance this time. Another recurrent coronal hole (CH426) is currently rotating into view at the east limb. CH426 appears to have grown over the last solar rotation.
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.
The geomagnetic field is expected to be quiet to unsettled on October 18-21, the first day because of CME effects, then due to weak coronal hole effects.
|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:||21||24|
|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)|
|2009.07||68.2||3.2||3.6 (+0.9)||5.49 / 4.55|
|2009.08||67.3||0.0||4.8 (+1.2)||5.70 / 4.89|
|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||(13.9 predicted, +1.6)||10.22 / 10.24|
|2010.05||73.8||8.7||(15.2 predicted, +1.3)||9.18 / 8.15|
|2010.06||72.5||13.6||(16.7 predicted, +1.5)||8.17 / 6.85|
|2010.07||79.8||16.1||(18.3 predicted, +1.6)||6.31 / 5.15|
|2010.08||79.2||19.6||(19.5 predicted, +1.2)||8.49 / 7.77|
|2010.09||81.1||25.2||(20.7 predicted, +1.2)||5.33|
|2010.10||78.9 (1)||13.7 (2A) / 24.9 (2B)||(23.1 predicted, +2.4)||(5.44)|
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.