Last major update issued on July 19, 2013 at 04:50 UTC.
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[Solar cycles 23-24 (last update July 1, 2013)] [Cycle 24 progress (last update July 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update July 1, 2013)]
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[POES auroral activity level since October
2009 - updated January 26, 2013]
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[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet to minor storm on July 18. Solar wind speed at SOHO ranged between 328 and 545 km/s, most of the day under the influence of a high speed stream from CH575.
Solar flux measured at 20h UTC on 2.8 GHz was 114.8 (decreasing 18.4 over the last solar rotation). The Potsdam WDC planetary A index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 15.4). Three hour interval K indices: 11224542 (planetary), 10224433 (Boulder).
The background x-ray flux was at the class B3 level.
At midnight UTC the visible solar disk had 13 spotted active regions (in 2K resolution SDO images).
Region 11791 [S13W33] decayed further and was quiet.
Region 11793 [N20E23] developed slowly and has weak polarity intermixing.
Region 11795 [S06E06] decayed slowly and quietly.
Region 11796 [S12W54] was quiet and stable.
Region 11797 [S18W03] decayed slowly and quietly.
New region 11798 [S13E43] emerged on July 17 and was numbered the next day by SWPC as the region lost a few spots.
New region 11799 [S18E63] rotated into view on July 17 and got its NOAA number the following day.
New region 11800 [S11E67] rotated into view on July 17 with SWPC numbering the region the next day.
Spotted regions not numbered by SWPC:
S2543 [S28W38] was quiet and stable.
S2550 [S21E08] developed slightly and was quiet.
S2553 [N13E02] lost some spots and was quiet.
New region S2557 [S10E77] rotated into view with a penumbra spot.
New region S2558 [S15W44] emerged with a penumbra spot.
July 17-18: No obviously Earth directed CMEs were observed in LASCO and
July 16: A faint halo CME was observed from 05:30 UTC in LASCO imagery, its source may have been a filament eruption near AR 11792 after 02 UTC.
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 coronal hole (CH575) in the northern hemisphere was in an Earth facing position on July 14-19.
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.
The geomagnetic field is expected to be quiet to active with a chance of minor storm intervals on July 19-22 due to effects from CH575. On July 19 there's a chance of a contribution to the disturbance from the CME observed on July 16.
|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
|Total spot count:||42||97||27|
|Sunspot number:||112||227||107||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||67||114||44||(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):||67||79||59||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|
possible cycle 24 max
|2013.01||127.1||62.9||(58.7 projected, -0.9)||4.69|
|2013.02||104.3||38.0||(58.3 projected, -0.4)||6.11|
|2013.03||111.3||57.9||(57.9 projected, -0.4)||10.56|
|2013.04||124.8||72.4||(57.5 projected, -0.4)||5.40|
|2013.05||131.4||78.7||(57.6 projected, +0.1)||9.73|
|2013.06||110.1||52.5||(57.9 projected, +0.3)||12.60|
|2013.07||119.7 (1)||55.3 (2A) / 95.2 (2B) / 61.0 (2C)||(58.0 projected, +0.1)||(10.58)|
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.