Last major update issued on September 27, 2014 at 06:00 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update September 1, 2014)] [Cycle 24 progress (last update September 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update September 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update September 1, 2014)]
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[New: Noon SDO count 1K 4K (large file)]
[POES auroral activity level October
2009 - December 2012]
[Solar polar fields vs solar cycles - updated September 6, 2014]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]
The geomagnetic field was quiet to active on September 26. Solar wind speed at SOHO ranged between 427 and 477 km/s under the influence of a high speed stream from CH636.
Solar flux at 20h UTC on 2.8 GHz was 170 (increasing 46.9 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 137.4. The Potsdam WDC planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.0). Three hour interval K indices: 33224323 (planetary), 34333423 (Boulder).
The background x-ray flux is at the class C1 level.
At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 350) and 10 active regions using 1K resolution (SN: 219) SDO images on the visible solar disk.
Region 12169 [N06W42] decayed slowly and quietly.
Region 12171 [S11W24] developed slowly and was mostly quiet.
Region 12172 [S11W02] gained a few spots while the central magnetic delta structure disappeared. A major flare is possible.
Region 12173 [S17W12] developed further and could produce a minor M class flare.
Region 12175 [N14W24] developed quickly and a magnetic delta structure in the southern part of a central penumbra formed. A major flare is possible.
Region 12176 [N07E31] decayed and could soon become spotless.
Region 12177 [N12E69] is a compact region which has minor M class flare potential. The region apparently had a magnetic delta structure early in the day.
Spotted regions not numbered (or interpreted differently) by SWPC:
S3848 [S14E52] was quiet and stable.
New region S3850 [S16E25] emerged with a penumbra spot.
New region S3851 [N10W03] emerged with a penumbra spot.
New region S3852 [S09W21] emerged with a few spots close to AR 12171.
New region S3853 [N29W19] emerged with a penumbra spot.
New region S3854 [N23W22] emerged with penumbra spots.
A region behind the southeast limb produced the most interesting flare of the day, this event was associated with a fast and impressive CME.
C2+ flares (GOES):
|Magnitude||Peak time (UTC)||Location||AR||Comment|
|C8.6 (LDE)||05:44||behind SE limb||CME|
September 24-26: 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 recurrent southern hemisphere coronal hole was in an Earth facing position on September 22-25.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is good.
The geomagnetic field is expected to be quiet to unsettled with a chance of active intervals on September 27-28 due to coronal hole effects and quiet on September 29.
|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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% 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:||123||220||119|
|Sunspot number:||203||350||219||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||153||261||160||(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):||122||123||121||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)|
|Month||Average solar flux||International sunspot number
|Smoothed sunspot number||Average ap
|166.3||102.3 (cycle peak)||78.4 (+1.1)||10.70|
|2014.03||149.9||148.5||91.9||(80.3 projected, +1.9)||4.88|
|2014.04||143.9||144.8||84.7||(81.0 projected, +0.7)||7.88|
|2014.05||129.7||132.9||75.2||(79.2 projected, -1.8)||5.75|
|2014.06||122.0||125.8||71.0||(76.6 projected, -2.6)||6.72|
|2014.07||137.4||141.8||72.5||(73.6 projected, -3.0)||4.50|
|2014.08||124.7||127.9||74.7||(70.1 projected, -3.5)||7.71|
|2014.09||141.8 (1)||107.1 (2A) / 123.6 (2B) / 87.6 (2C)||(65.9 projected, -4.2)||(9.6)|
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 WDC-SILSO 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 GFZ 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.