Last major update issued on June 7, 2013 at 04:05 UTC.
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[Solar cycles 1-20]
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[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet to minor storm on June 6. Solar wind speed at SOHO ranged between 443 and 554 km/s. A weak disturbance was observed during the first half of the day, after 16h UTC ACE data indicates the the beginning of the passage of a magnetic cloud. The interplantery magnetic field became stronger and swung nearly fully southwards causing active to minor storm conditions.
Solar flux measured at 20h UTC on 2.8 GHz was 109.0 (decreasing 15.8 over the last solar rotation). The Potsdam WDC planetary A index was 18 (STAR Ap - based on the mean of three hour interval ap indices: 18.1). Three hour interval K indices: 13333534 (planetary), 23343533 (Boulder).
The background x-ray flux was at the class B2 level.
At midnight UTC the visible solar disk had 6 spotted active regions (in 2K resolution SDO images).
Region 11758 [S14W67] was quiet and stable.
Region 11762 [S31W70] decayed and simplified magnetically.
Region 11764 [N13W78] decayed slowly and quietly.
Region 11765 [N08E04] developed slowly and quietly. There's weak polarity intermixing near the center of the region, C flares are possible.
Region 11766 [N18W58] decayed significantly and was quiet.
Spotted regions not numbered by SWPC:
New region S2463 [N13E54] emerged with penumbra spots.
June 4-6: 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 (CH572) in the southern hemisphere was in an Earth facing position on June 4-5.
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 good.
The geomagnetic field is expected to be quiet to minor storm on June 7, first under the influence of a magnetic cloud and late in the day due to effects from CH572. Quiet to active conditions are possible on June 8 becoming quiet to unsettled on June 9.
|Coronal holes (1)||Coronal mass ejection (2)||M and X class flares (3)|
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
|11763||2013.06.01||S14W66||see AR 11758|
|Total spot count:||31||53||23|
|Sunspot number:||71||113||73||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||54||68||38||(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):||43||40||40||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 max)||96.7 (cycle max)||61.1 (+1.2)||5.55|
possible cycle 24 max
|2012.12||108.6||40.8||(59.5 projected, -0.2)||3.44|
|2013.01||127.1||62.9||(59.1 projected, -0.4)||4.69|
|2013.02||104.3||38.0||(59.3 projected, +0.2)||6.11|
|2013.03||111.3||57.9||(58.9 projected, -0.4)||10.56|
|2013.04||124.8||72.4||(58.6 projected, -0.3)||5.40|
|2013.05||131.4||78.7||(58.7 projected, +0.1)||9.04|
|2013.06||109.4 (1)||14.9 (2A) / 74.3 (2B) / 69.1 (2C)||(59.0 projected, +0.3)||(17.77)|
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 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.