Solar Terrestrial Activity Report

Activity chart

Last major update issued on September 10, 2014 at 05:15 UTC. Update at 19:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[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)]

[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]

Recent activity

The geomagnetic field was quiet on September 9. Solar wind speed at SOHO ranged between 328 and 433 km/s, weakly under the influence of a low speed stream from CH634.

Solar flux at 20h UTC on 2.8 GHz was 159 (increasing 56.1 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 133.3. The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.1). Three hour interval K indices: 22121122 (planetary), 22113322 (Boulder).

The background x-ray flux is at the class B8 level.

At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 321) and 11 active regions using 1K resolution (SN: 216) SDO images on the visible solar disk.

Region 12155 [S20W06] has weak polarity intermixing and was quiet.
Region 12157 [S14E06] was mostly quiet. There is still a magnetic delta structure in the southern part of the largest penumbra. An M class flare is possible.
Region 12158 [N16E15] was quiet after the flare late on September 8. The region is losing its magnetic delta, however, there is still a chance of a major flare.
Region 12159 [S21E19] was quiet and stable.
Region 12161 [S13W48] was quiet and stable.
Region 12162 [N09W45] lost a few spots and was quiet.
Region 12163 [S16E37] was quiet and stable.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3791 [N14W32] decayed slowly and quietly.
S3808 [S09W33] decayed slowly and quietly.
New region S3811 [S23E34] was split off from AR 12159.
New region S3812 [S14E59] emerged with penumbra spots.
New region S3813 [N14E48] was observed with a penumbra spot.
New region S3814 [N13E02] emerged with a penumbra spot.

Minor update posted at 19:05 UTC on September 10: AR 12158 produced a long duration major X1.6 flare peaking at 17:45 UTC while near the center of the disk. A wave travelled quuckly across a large part of the visible solar disk after the peak of the flare. A large and fast CME is likely to have been generated and could reach Earth on September 12.

C2+ flares (GOES):

Magnitude Peak time (UTC) Location AR Comment
C3.2/1N 12:26 S08E12 12157  

Coronal mass ejections (CMEs)

September 7-8: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
September 9: An asymmetric full halo CME was observed after the M4.5 flare in AR 12158 late on Sept.8.

Coronal holes

[Coronal hole history (since October 2002)]
[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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on September 10. Late on September 11 or early on September 12 a CME could arrive and cause unsettled to minor storm conditions.

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.

Active solar regions

(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
detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlay
Comment
SWPC Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
S3781 2014.08.31       S08W48           plage
12154 2014.09.01
2014.09.02
      S16W58         plage
S3791 2014.09.03   2 1 N14W32 0008   HRX  
12155 2014.09.03 9 25 10 S21W08 0060 DAC DAI beta-gamma

location: S20W06

12157 2014.09.03
2014.09.04
39 70 42 S14E03 0480 EKC EKC beta-gamma-delta
12156 2014.09.03
2014.09.04
      N15W14           plage
12158 2014.09.04 25 49 31 N15E14 0420 DKC DKC beta-gamma

area: 0800

S3796 2014.09.04       N08W52           plage
12159 2014.09.05 5 12 5 S21E22 0010 BXO CRO location: S21E19
12162 2014.09.05
2014.09.06
7 7 4 N09W48 0030 CRO DRO area: 0050

location: N09W45

S3799 2014.09.05       S04W30           plage
12161 2014.09.06 1 2 2 S13W50 0010 HSX CRO location: S13W48
12163 2014.09.06
2014.09.07
6 16 8 S17E37 0110 DAO DSI  
S3806 2014.09.07       S09W51           plage
S3808 2014.09.08   1   S09W33 0003   AXX  
S3809 2014.09.08       N24W50         plage
S3811 2014.09.09   2   S23E34 0005   AXX    
S3812 2014.09.09   3 1 S14E59 0010   BXO    
S3813 2014.09.09   1 1 N14E48 0003   AXX    
S3814 2014.09.09   1 1 N13E02 0005   AXX    
Total spot count: 92 191 106  
Sunspot number: 162 321 216  (total spot count + 10 * number of spotted regions)
Weighted SN: 125 233 148  (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): 97 112 119 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number Average ap
(3)
Measured 1 AU
2013.05 131.4 134.3 78.7 59.9 (+2.0) 9.73
2013.06 110.1 113.7 52.5 62.6 (+2.7) 12.60
2013.07 115.5 119.3 57.0 65.5 (+2.9) 9.47
2013.08 114.6 118.3 66.0 69.0 (+3.5) 8.27
2013.09 102.6 103.7 36.9 73.1 (+4.1) 5.23
2013.10  132.1 131.2 85.6 75.0 (+1.9) 7.71
2013.11  148.3 145.1 77.6 75.4 (+0.4) 5.68
2013.12 147.7 143.1 90.3 76.0 (+0.6) 4.68
2014.01 157.4 152.4 81.8 77.3 (+1.3) 5.44
2014.02 170.3
(cycle peak)
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
2014.09 146.7 (1)   40.2 (2A) / 134.1 (2B) / 77.6 (2C) (65.9 projected, -4.2) (6.8)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
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.