Last major update issued on July 29, 2012 at 06:55 UTC.
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[Solar cycles 21-24 (last update June 2, 2012)] [Cycle 24 progress NEW]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 2, 2012)]
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[POES auroral activity level since October
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[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was quiet to active on July 28. Solar wind speed at SOHO ranged between 307 and 377 km/s under the influence of a low speed stream, probably from CH525.
Solar flux measured at 20h UTC on 2.8 GHz was 126.6 (decreasing 6.8 over the last solar rotation). The Potsdam WDC planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.3). Three hour interval K indices: 12223343 (planetary), 11223334 (Boulder).
The background x-ray flux is at the class B9 level.
At 19h UTC the visible solar disk had 14 spotted active regions (in 2K resolution SDO images).
Region 11526 [S16W38] was quiet and stable.
Region 11527 [N27E04] gained a tiny trailing spot.
Region 11528 [N17W01] decayed and simplified with only same polarity spots remaining.
Region 11529 [S11E05] lost the tiny spots and was quiet.
Region 11530 [S19E15] was mostly quiet and stable.
Region 11531 [N13W84] decayed quickly with only a single small spot visible.
Region 11532 [S21E46] has a magnetic delta structure in the largest leading penumbra and many spots spread out over a large area. Further M class flaring is possible. Flare: M6.1/2N at 20:56 UTC. A partial halo CME was observed after this event, the CME could have a minor Earth directed component.
Region 11533 [S28E05] was mostly quiet and stable.
New region 11534 [N17E55] emerged early on July 27 and was numbered by SWPC the next day.
Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1822 [N17W36] reemerged with a tiny spot.
New region S1827 [N17E12] emerged with a tiny spot.
New region S1828 [S22E14] was split off from AR 11530 and developed slowly.
New region S1829 [S02W15] emerged with a small spot.
New region S1830 [N08W47] emerged with a tiny spot.
July 26-27: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
July 28: The partial halo CME produced by the M6 event in AR 11532 could have a minor Earth directed component.
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
A recurrent trans equatorial coronal hole (CH525) was in an Earth facing position on July 25-27.
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. Propagation on long distance northeast-southwest paths is fair to good.
The geomagnetic field is expected to be quiet to active on July 29-30 due to effects from CH525 and quiet on July 31. Weak effects from the July 28 CME are possible on August 1.
|Coronal holes (1)||Coronal mass ejection (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:||38||100||49|
|Sunspot number:||108||240||149||(total spot count + 10 * number of spotted regions)|
|Weighted penumbral SN:||63||136||85||(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):||65||84||82||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K|
|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)|
|2012.01||132.5||58.3||(65.0 projected, +1.6)||7.15|
|2012.02||106.5||33.1||(66.5 projected, +1.5)||8.81|
|2012.03||114.7||64.2||(67.2 projected, +0.7)||16.08|
|2012.04||113.0||55.2||(66.5 projected, -0.7)||10.10|
|2012.05||121.5||69.0||(64.8 projected, -1.7)||7.06|
|2012.06||119.6||64.5||(64.0 projected, -0.8)||10.08|
|2012.07||133.7 (1)||89.9 (2A) / 99.5 (2B)||(65.0 projected, +1.0)||(14.99)|
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 quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC 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.