Solar Terrestrial Activity Report

Activity chart

Last major update issued on September 12, 2014 at 05:20 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 to unsettled on September 11. Solar wind speed at SOHO ranged between 325 and 446 km/s. A weak to moderate solar wind shock was observed at SOHO at 23:02 UTC, the arrival of the September 9 CME. While the interplanetary magnetic field initially saw some moderately southward swings, the IMF has been mostly weakly northwards since 03h UTC on Sept.12.

Solar flux at 20h UTC on 2.8 GHz was 151 (increasing 37.9 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 133.0. The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices:9.8). Three hour interval K indices: 33221113 (planetary), 33444313 (Boulder).

The background x-ray flux is at the class B7 level.

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 272) and 11 active regions using 1K resolution (SN: 187) SDO images on the visible solar disk.

Region 12155 [S19W31] decayed slowly and quietly.
Region 12157 [S14W19] decayed significantly and lost the magnetic delta structure. C and minor M class flaring is possible.
Region 12158 [N16W12] decayed with the large penumbra splitting in the northern section. The northernmost penumbra developed a weak magnetic delta structure. An M class flare is possible.
Region 12159 [S21W07] decayed slowly and quietly.
Region 12161 [S12W80] decayed slowly and quietly.
Region 12163 [S16E09] was mostly quiet and stable.
New region 12164 [S13E27] emerged on September 9 and was numbered by SWPC 2 days later.
New region 12165 [S08E64] rotated into view on September 10 with SWPC numbering the region the next day.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3808 [S13W62] reemerged with a penumbra spot.
S3811 [S24E08] was quiet and stable.
New region S3816 [S10E38] emerged with penumbra spots.
New region S3817 [N11E44] emerged with penumbra spots.

An interesting active region just behind the northeast limb produced most of the flares recorded during the day.

C2+ flares (GOES):

Magnitude Peak time (UTC) Location AR Comment
C4.4 03:35 NE limb    
C2.0 11:54   12163  
C2.4 14:30   12157  
M2.1 15:20 NE limb    
M1.4 21:01 NE limb    

Coronal mass ejections (CMEs)

September 9: An asymmetric full halo CME was observed after the M4.5 flare in AR 12158 late on Sept.8.
September 10: A large and wide Earth directed asymmetric full halo CME was observed after the X1 event in AR 12158.
September 11: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

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. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet to major storm on September 12-13 due to CME effects, isolated severe storm intervals are possible when the Sept.10 CME arrives. Quiet to unsettled conditions are likely on September 14.

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
12154 2014.09.01
2014.09.02
      S16W86           plage
S3791 2014.09.03       N10W57         plage
12155 2014.09.03 5 9 6 S19W34 0030 BXO BXO location: S19W31
12157 2014.09.03
2014.09.04
34 66 30 S14W24 0260 EKC EAC beta-gamma

location: S14W19

12156 2014.09.03
2014.09.04
      N15W42           plage
12158 2014.09.04 23 40 22 N16W12 0400 DKC DKC beta-gamma-delta

area: 0640

12159 2014.09.05 2 7 2 S21W09 0010 AXX BXO  
12162 2014.09.05
2014.09.06
2     N10W71 0010 BXO    

spotless

S3799 2014.09.05       S04W43           plage
12161 2014.09.06 1 1 1 S12W79 0030 AXX AXX area: 0003
12163 2014.09.06
2014.09.07
2 11 5 S17E10 0050 CAO CSO  
S3808 2014.09.08   1 1 S13W62 0003   AXX    
S3811 2014.09.09   3 3 S24E08 0012   AXX  
12164 2014.09.09
2014.09.11
2 3 2 S13E28 0020 CRO HAX  
S3813 2014.09.09       N15E20         plage
S3814 2014.09.09       N13W24           plage
12165 2014.09.10
2014.09.11
3 6 4 S08E63 0020 CAO CRO  
S3816 2014.09.11   2 1 S10E38 0003   AXX    
S3817 2014.09.11   3   N11E44 0005   BXO    
Total spot count: 74 152 77  
Sunspot number: 164 272 187  (total spot count + 10 * number of spotted regions)
Weighted SN: 107 180 105  (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): 98 95 103 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
2014.09 148.5 (1)   51.1 (2A) / 139.3 (2B) / 81.7 (2C) (65.9 projected, -4.2) (7.0)

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.