Last major update issued on July 23, 2010 at 05:30 UTC.
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[Solar cycles 21-24 (last update July 2, 2010)]
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[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update July 4, 2010)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update July 3, 2010)]
The geomagnetic field was quiet on July 22. Solar wind speed ranged between 327 and 379 km/s. The leading part of a high speed stream associated with CH414 appears to have reached ACE early on July 23.
Solar flux measured at 20h UTC on 2.8 GHz was 87.7. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.3). Three hour interval K indices: 11112122 (planetary), 11122212 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight there were 2 spotted regions on the visible solar disk.
Region 11089 decayed somewhat, While the spot count remained fairly high, some penumbral area was lost. C flares are possible.
Spotted regions not numbered by NOAA/SWPC:
[S790] This region emerged in the northeast quadrant late on July 21 and showed little change on July 22. Location at midnight: N14E15.
July 20-22: 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 trans equatorial coronal hole (CH414) was in an Earth facing position on July 19-21. A recurrent coronal hole (CH415) in the northern hemisphere was Earth facing on July 21-23.
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 fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet to active on July 23-27 due to effects from CH414 and CH415.
|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:||29||36|
|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||(9.2 predicted, +0.9)||2.93 / 3.07|
|2010.02||84.7||18.8||(10.4 predicted, +1.2)||4.15 / 4.61|
|2010.03||83.4||15.4||(12.1 predicted, +1.7)||4.58 / 4.65|
|2010.04||75.9||7.9||(13.7 predicted, +1.6)||10.22 / 10.24|
|2010.05||73.8||8.8||(15.0 predicted, +1.3)||9.18 / 8.15|
|2010.06||72.5||13.5||(16.4 predicted, +1.4)||8.17 / 6.85|
|2010.07||77.9 (1)||14.0 (2)||(18.0 predicted, +1.6)||(5.32)|
1) Running average based on the
daily 20:00 UTC observed solar flux
value at 2800 MHz.
2) 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.
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 partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.