|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 quiet to active on September 19. Solar wind speed at SOHO ranged between 366 and 449 km/s. The increased geomagnetic activity during the first half of the day was likely associated with a solar sector boundary crossing.
Solar flux at 20h UTC on 2.8 GHz was 105.7 (decreasing 11.5 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 106.1. The Potsdam WDC planetary A index was 14 (STAR Ap - based on the mean of three hour interval ap indices: 13.9). Three hour interval K indices: 34431013 (planetary), 34442222 (Boulder).
The background x-ray flux is at the class B3 level.
At the time of counting spots (see image time), spots were observed in 5 active regions using 2K resolution (SN: 105) and 5 active regions using 1K resolution (SN: 73) SDO images on the visible solar disk.
Region 12415 [S19W38] decayed slowly and was mostly
Region 12418 [S15W08] decayed slowly and quietly.
Region 12419 [N12W04] decayed slowly and was mostly quiet.
Spotted regions not numbered (or interpreted differently) by SWPC:
S4765 [S19W46] was quiet and stable.
New region S4769 [N09E84] rotated partly into view. The region produced a C1.4 (unreported by SWPC) flare at 21:22 UT and further C class flaring is likely.
Update added at 08:15 UT: A fairly strong solar wind shock was observed at ACE at 05:27 UT. Minor to major geomagnetic storm conditions have been observed afterwards. It's not yet clear if this CME is related to the long duration event on September 18.
AR S4769 produced an M1.5 flare at 05:03 UT. Several spots have rotated into view and this looks like an interesting group.
|Magnitude||Peak time (UTC)||Location||AR||Recorded by||Comment|
September 17, 19: No obviously Earth directed CMEs were observed in
available LASCO imagery.
September 18: A CME was observed off the south pole and parts of the southwest and southeast limbs after the C2 LDE in AR 12415. There is a minor chance that the northernmost parts of the CME could reach Earth on September 21.
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 narrow recurrent trans equatorial coronal hole (CH690) was in an Earth facing position on September 16-17. Another recurrent trans equatorial coronal hole (CH691) could rotate across the central meridian on September 21-22.
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 poor to fair.
The geomagnetic field is expected to be quiet to unsettled on September 20 due to effects from CH690, isolated active intervals are possible. Quiet conditions are likely on September 21-23. There is a slight chance of a weak CME impact on September 21, if that occurs unsettled to active conditions will be likely. Effects from CH691 could cause quiet to minor storm conditions on September 24-25.
|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:||31||55||23|
|Sunspot number:||61||105||73||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||51||85||53||(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||58||62||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||(93.2)||33.9 (2A) / 53.5 (2B) / 69.2 (2C)||(67.0 projected, +0.3)||(18.0)|
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.