|Charts (* = updated daily)||Data and archive|
|Solar wind (*)||Solar and geomagnetic data - last month (*)|
|Electron fluence (*)||Archived daily reports and monthly data from 2003.01 (September 1, 2015)|
|Solar cycle||Solar cycles 23-24 (September 1, 2015)||Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)|
|Cycle 24 progress (September 1, 2015)||Noon SDO sunspot count 1K Reference: 4K (large file) (*)|
|Solar cycles 1-24 (July 17, 2015)||POES auroral activity level October 2009 - December 2012|
|Comparison of cycles 21, 22, 23 and 24 (September 1, 2015)||3rd SSN Workshop, Tucson, 2013|
|Comparison of cycles 12, 13, 14, 16 and 24 (September 1, 2015)||4th SSN Workshop, Locarno, 2014|
|Solar polar fields vs solar cycles (September 16, 2015)|
The geomagnetic field was very quiet on September 27. Solar wind speed at SOHO ranged between 380 and 455 km/s.
Solar flux at 20h UTC on 2.8 GHz was 127.5 (increasing 36.5 over the last solar rotation, the measurement may have been slightly flare enhanced). The 90 day 10.7 flux at 1 AU was 106.4. The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4). Three hour interval K indices: 11100011 (planetary), 11102222 (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 12 active regions using 2K resolution (SN: 296) and 9 active regions using 1K resolution (SN: 178) SDO images on the visible solar disk.
Region 12420 [N09W20] decayed slowly and quietly.
Region 12421 [N15W36] decayed quickly and was mostly quiet.
Region 12422 [S20W14] developed gaining penumbral area and becoming even more complex magnetically. Further M class flares are likely and there is a minor chance of an X class event.
Region 12423 [S09W66] displayed quick growth gaining many spots with a large increase in penumbral area. The region became much more complex as 3 magnetic deltas formed. Further M class flaring is possible. The region produced an M3.6 flare at 03:55 UT on September 28.
Region 12424 [N12W56] decayed slowly and quietly.
Region 12425 [S05W28] decayed slowly and quietly.
Region 12426 [N17E49] decayed slowly and quietly.
New region 12427 [N17E49] emerged rapidly with many spots and weak polarity intermixing. C flares are possible. If current development continues a minor M class flare will become possible.
Spotted regions not numbered (or interpreted differently) by SWPC:
S4781 [S19E38] was quiet and stable.
New region S4784 [S05W50] emerged with penumbra spots.
New region S4785 [N65W05] emerged with a tiny spot at a high latitude.
New region S4786 [S10W19] emerged with a tiny spot.
|Magnitude||Peak time (UTC)||Location||AR||Recorded by||Comment|
|M1.9/1F||10:40||S22W08||12422||GOES15||Flare in 12423 as well at the same time|
|C2.2||13:46||12422||GOES15||Flare in 12423 a few minutes later|
|C4.3||16:49||S09W63||12423||GOES15||Most likely source, activity in 12422 as well|
|C9.3/1N||19:58||12422||GOES15||SWPC reports a C9.4 recorded by GOES13 at exactly the same time and thereby counts one flare twice|
|C7.7||21:12||12423||SDO/EVE||SWPCs flare definition makes it difficult for them to separate events occurring in different places and closely spaced in time|
September 25-27: No obviously Earth directed CMEs were observed in available LASCO imagery.
history (since October 2002)]
[Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago]
A recurrent northern hemisphere coronal hole (CH692) could rotate into an Earth facing position on September 29. A small coronal hole between ARs 12425 and 12422 was in a potentially geoeffective position on September 26 and could cause a brief disturbance on September 29. A northern hemisphere coronal hole (CH693) was in an Earth facing position on September 26-27, however, it is uncertain if this CH is too far to the north to cause a geomagnetic disturbance.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on September 28. Quiet is likely on September 29-30 as well, however, there is some uncertainty as CH693 could cause unsettled and active intervals if it isn't too far to the north.
|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 green.
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.
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 overlays
|Total spot count:||74||176||88|
|Sunspot number:||154||296||178||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||102||205||117||(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):||169||163||151||k * (sunspot number)
As of July 1, 2015: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.85 for MSN 1K (MSN=Magnetic Sunspot Number)
|Month||Average solar flux||International sunspot number
|Smoothed sunspot number (4)||Average
|166.3||146.1 (cycle peak)||110.5 (+1.2)||10.70|
|2014.04||143.9||144.8||112.5||116.4 (+2.1) (solar max)||7.88|
|2015.03||125.9||124.6||54.5||(82.1 projected, -4.5)||16.14|
|2015.04||128.8||129.7||78.0||(78.0 projected, -4.1)||10.73|
|2015.05||120.0||122.6||90.0||(75.3 projected, -2.7)||8.29|
|2015.06||122.3||126.1||68.3||(71.6 projected, -3.7)||13.15|
|2015.07||107.0||110.8||66.4||(67.9 projected, -3.7)||8.83|
|2015.08||105.4||108.0||64.6||(66.7 projected, -1.2)||14.58|
|2015.09||(98.7)||61.9 (2A) / 68.7 (2B) / 81.5 (2C)||(67.0 projected, +0.3)||(17.1)|
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).
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.
4) Updated to new data set from WDC-SILSO on July 1, 2015
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 Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.