Last major update issued on August 19, 2013 at 06:40 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)]
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[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 July 28, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet on August 18. Solar wind speed at SOHO ranged between 458 and 574 km/s under the decreasing influence of a high speed stream from CH579.
Solar flux measured at 20h UTC on 2.8 GHz was 126.1 (increasing 16.2 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: 5.4). Three hour interval K indices: 21221221 (planetary), 11322222 (Boulder).
The background x-ray flux was at the class B4 level.
At midnight UTC the visible solar disk had 17 spotted active regions (in 2K resolution SDO images).
Region 11817 [S20W76] decayed slowly and quietly.
Region 11818 [S06W47] was mostly quiet, however, there is still a magnetic delta structure in the northern part. C and M class flares are possible.
Region 11820 [S13W04] developed slowly and quietly.
Region 11822 [S07E19] decayed slowly and quietly.
Region 11823 [S07E32] developed slowly and quietly with the trailing spot close to developing umbra.
Region 11824 [S13W25] matured and was quiet.
New region 11825 [N15W12] emerged on August 17 and was numbered by SWPC the next day. The region has many spots, polarity intermixing and a weak magnetic delta structure in the northern section. C flares are likely and an M class flare is possible.
New region 11826 [N08E21] emerged on August 17 and got its NOAA number the next day. Slow decay was observed on August 18.
New region 11827 [S19E72] rotated partly into view on August 17 and was numbered by SWPC the next day. At least C flares are possible.
Spotted regions not numbered by SWPC:
S2601 [S09E08] was quiet and stable.
S2602 [N22W20] reemerged with penumbra spots.
S2613 [N22W03] was quiet and stable.
New region S2616 [N13E79] rotated into view.
New region S2617 [N12E16] emerged with penumbra spots.
New region S2618 [N06W55] emerged with a penumbra spot.
New region S2619 [N05W19] emerged with a penumbra spot.
New region S2620 [S10E31] emerged with penumbra spots.
August 16, 18: No obviously Earth directed CMEs were observed in LASCO and
August 17: An asymmetric full halo CME was observed after the M class events in AR 11818. The CME could reach Earth on August 20.
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) will rotate into 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 poor to fair.
The geomagnetic field is expected to be quiet on August 19. The halo CME observed on August 17 could reach Earth on August 20 and cause unsettled to minor storm conditions. Quiet to active conditions are likely on August 21-22 as a high speed stream from CH580 becomes geoeffective.
|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
|S2620||2013.08.18||2||2||S10E31||0008||BXO||split off from AR 11823|
|Total spot count:||44||105||52|
|Sunspot number:||134||275||182||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||74||146||93||(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):||80||96||100||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||112.5 (1)||53.4 (2A) / 92.0 (2B) / 55.3 (2C)||(57.6 projected, -0.1)||(7.58)|
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.