Last major update issued on September 28, 2014 at 05:40 UTC.
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The geomagnetic field was quiet to active on September 27. Solar wind speed at SOHO ranged between 385 and 465 km/s under the decreasing influence of a high speed stream from CH636.
Solar flux at 20h UTC on 2.8 GHz was 181 (increasing 56.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 138.0. 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: 44322221 (planetary), 44432221 (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 14 active regions using 2K resolution (SN: 376) and 14 active regions using 1K resolution (SN: 259) SDO images on the visible solar disk.
Region 12171 [S11W39] decayed slowly and quietly.
Region 12172 [S11W14] decayed slowly and produced a few low level C flares. A major flare is still possible.
Region 12173 [S17W25] developed further with the trailing polarity area interacting with the leading polarity area of AR 12172. A major M5.1 flare was recorded in the trailing polarity area at 02:58 UTC on September 28. This CME may have been associated with a CME, however, relevant imagery is not available as this is written.
Region 12175 [N14W38] matured somewhat and has a moderately strong magnetic delta structure within a central penumbra. A major flare is possible.
Region 12176 [N07E18] was quiet and stable.
Region 12177 [N12E55] is a compact region with minor M class flare potential.
New region 12178 [S01E74] rotated into view and could be capable of producing a minor M class flare.
Spotted regions not numbered (or interpreted differently) by SWPC:
S3848 [S14E39] was quiet and stable.
S3852 [S08W36] decayed slowly and quietly.
New region S3857 [S11E83] rotated into view.
New region S3858 [N03E83] rotated into view.
New region S3859 [N11E39] was observed with penumbra spots.
New region S3860 [S00W05] was observed with a penumbra spot.
New region S3861 [N12E63] was split off from AR 12177.
C2+ flares (GOES):
|Magnitude||Peak time (UTC)||Location||AR||Comment|
September 25-27: 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]
No obvious coronal holes are currently in or near Earth facing positions.
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 fair.
The geomagnetic field is expected to be quiet to unsettled on September 28 due to coronal hole effects and quiet on September 29-30.
|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: 0-30% 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.
|Active region||Date numbered
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlay
|Total spot count:||99||236||119|
|Sunspot number:||159||376||259||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||139||282||165||(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):||95||132||142||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||143.3 (1)||112.4 (2A) / 124.9 (2B) / 90.7 (2C)||(65.9 projected, -4.2)||(9.7)|
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.