Last major update issued on August 12, 2012 at 06:55 UTC.
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The geomagnetic field was quiet to unsettled on August 11. Solar wind speed at SOHO ranged between 286 and 355 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 119.7 (decreasing 20.8 over the last solar rotation). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.3). Three hour interval K indices: 01111123 (planetary), 00112222 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight UTC the visible solar disk had 9 spotted active regions (in 2K resolution SDO images).
Region 11537 [N13W68] decayed slowly and quietly.
Region 11538 [S23W75] decayed slowly and quietly.
Region 11540 [S25W48] decayed slowly. The region was the source of a long duration M1.0/2N event peaking at 12:20 UTC.
Region 11542 [S13E08] decayed slowly and still has a magnetic delta structure in a trailing penumbra. An M flare is possible.
Region 11543 [N21E20] was quiet and stable.
Region 11544 [S31W28] decayed further and was mostly quiet.
New region 11545 [S14W22] emerged on August 9 and was numbered by SWPC 2 days later. The region decayed slightly on August 11.
Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
New region S1853 [S25E00] emerged with a tiny spot.
New region S1854 [S01W14] emerged with a tiny spot.
August 9-11: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
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 coronal hole (CH527) in the southern hemisphere was in an Earth facing position on August 9-10. A coronal hole (CH528) in the northern hemisphere was Earth facing on August 10-11. A recurrent coronal hole in the southern hemisphere will likely become Earth facing on August 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. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to unsettled on August 12-14 due to weak effects from CH527 and CH528.
|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
|1||7||2||S14W21||0010||BXO||BXO||BXO with 1 spot is impossible|
|Total spot count:||28||55||27|
|Sunspot number:||98||145||97||(total spot count + 10 * number of spotted regions)|
|Weighted penumbral SN:||58||86||58||(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):||59||51||53||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
|2012.02||106.5||33.1||(67.4 projected, +1.9)||8.81|
|2012.03||114.7||64.2||(68.1 projected, +0.7)||16.08|
|2012.04||113.0||55.2||(67.5 projected, -0.6)||10.10|
|2012.05||121.5||69.0||(65.8 projected, -1.7)||7.06|
|2012.06||119.6||64.5||(65.0 projected, -0.8)||10.08|
|2012.07||133.9||66.5||(66.0 projected, +1.0)||13.90|
|2012.08||132.8 (1)||41.3 (2A) / 116.5 (2B)||(68.6 projected, +2.6)||(7.64)|
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.