Last major update issued on September 20, 2014 at 06:15 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)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update September 6, 2014)]
[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 unsettled to minor storm on September 19. Solar wind speed at SOHO ranged between 332 and 498 km/s. The disturbance that began during the evening of September 18 was likely associated with a co-rotating interaction region caused by a large southern hemisphere coronal hole. An extension of that coronal hole rotated across the central meridian on September 15 and was the most likely source of the disturbance on September 19.
Solar flux at 20h UTC on 2.8 GHz was 122 (decreasing 10.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 134.4. The Potsdam WDC planetary A index was 22 (STAR Ap - based on the mean of three hour interval ap indices: 21.5). Three hour interval K indices: 45333443 (planetary), 45424432 (Boulder).
The background x-ray flux is at the class B4 level.
At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 149) and 7 active regions using 1K resolution (SN: 92) SDO images on the visible solar disk.
Region 12164 [S14W76] decayed quickly leaving only
penumbra spots by the end of the day.
Region 12166 [N13W22] decayed slowly and was mostly quiet.
Region 12167 [N07W06] decayed slowly and quietly.
Region 12168 [S21E20] decayed slowly and quietly.
Region 12169 [N04E39] decayed slowly and was quiet.
Region 12170 [N10E40] was quiet and stable.
New region 12171 [S10E67] rotated into view on September 18 and was numbered by SWPC the next day. Further C flares are possible.
Spotted regions not numbered (or interpreted differently) by SWPC:
S3824 [S10W55] reemerged with a penumbra spot.
New region S3832 [S15E78] rotated into view.
New region S3833 [N07W32] emerged with penumbra spots.
|Magnitude||Peak time (UTC)||Location||AR||Comment|
September 17-19: 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 northern hemisphere coronal hole (CH635) could rotate into an Earth facing position on September 21. A recurrent southern hemisphere coronal hole will likely rotate into an Earth facing positon on September 23.
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 20-22.
|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.
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:||21||49||22|
|Sunspot number:||91||149||92||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||51||72||45||(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):||55||52||51||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||142.0 (1)||82.4 (2A) / 130.1 (2B) / 84.5 (2C)||(65.9 projected, -4.2)||(9.2)|
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.