Last major update issued on August 22, 2013 at 04:55 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update August 1, 2013)] [Cycle 24 progress (last update August 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update August 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update August 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update August 4, 2013)]
[POES auroral activity level since October
2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated August 20, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet to active on August 21. Solar wind speed at SOHO ranged between 381 and 506 km/s. From midnight until about 14h UTC the field was under the influence of the CME related distrubance which began late on August 20. Between 14 and 18:30h UTC there was a transition phase between the CME disturbance and a commencing high speed stream from CH580. After 18:30 the high speed stream has been the dominant solar wind source.
Solar flux measured at 20h UTC on 2.8 GHz was 130.4 (increasing 24.5 over the last solar rotation). The Potsdam WDC planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 16.0). Three hour interval K indices: 24233344 (planetary), 34243333 (Boulder).
The background x-ray flux was at the class B4 level.
At midnight UTC the visible solar disk had 11 spotted active regions (in 2K resolution SDO images).
Region 11820 [S13W47] matured and was mostly quiet.
Region 11823 [S07W08] decayed slowly and quietly.
Region 11824 [S13W69] decayed slowly and quietly.
Region 11825 [N13W57] decayed slowly and quietly.
Region 11827 [S18E33] was quiet. Spots became smaller with some fragmenting observed, the region appears to be decaying.
Region 11828 [N14E42] decayed slowly and was mostly quiet.
New region 11829 [N05W60] emerged on August 20 and got its NOAA number the next day.
New region 11830 [S06W38] emerged with several spots.
New region 11831 [N13W34] emerged on August 20 and was numbered by SWPC the next day.
Spotted regions not numbered by SWPC:
S2623 [S19E12] was quiet and stable.
S2625 [N25W34] was quiet and stable.
August 19, 21: No obviously Earth directed CMEs were observed in LASCO and
August 20: At least a partial halo CME was observed from 09:18 UTC in LASCO imagery following a large filament eruption in the southern hemisphere. A backsided full halo CME was observed early in the day.
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 (CH580) was in an Earth facing position on August 18-19. A coronal hole (CH581) in the northern hemisphere will likely rotate into an Earth facing position on August 22.
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 August 22 due to effects from CH580. The CME observed on August 20 could reach Earth on August 23 and cause unsettled to minor storm conditions. Quiet to unsettled is likely on August 24-26 with a chance of active intervals on August 25-26 due to effects from CH581.
|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 2K resolution) Compare to the previous day's image. 0.5k image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue 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
rotated out of view
plage, SWPC/USAF moved this region to the location of AR
real location: N08W20
|Total spot count:||49||112||51|
|Sunspot number:||149||222||151||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||89||149||88||(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):||89||78||83||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
|2011.11||153.5 (cycle peak)||96.7 (cycle peak)||61.1 (+1.2)||5.55|
likely cycle 24 max
|2013.02||104.3||38.0||(57.8 projected, -0.9)||6.11|
|2013.03||111.3||57.9||(57.3 projected, -0.5)||10.56|
|2013.04||124.8||72.4||(57.3 projected, 0.0)||5.40|
|2013.05||131.4||78.7||(57.3 projected, 0.0)||9.73|
|2013.06||110.1||52.5||(57.6 projected, +0.3)||12.60|
|2013.07||115.5||57.0||(57.7 projected, +0.1)||9.47|
|2013.08||115.0 (1)||67.1 (2A) / 99.1 (2B) / 60.1 (2C)||(57.6 projected, -0.1)||(7.61)|
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) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
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 the 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.