Solar Terrestrial Activity Report

Activity chart

Last major update issued on September 2, 2014 at 03:40 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 August 9, 2014)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated July 18, 2014]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was quiet to unsettled on September 1. Solar wind speed at SOHO ranged between 356 and 452 km/s under the influence of a high speed stream from CH632.

Solar flux at 20h UTC on 2.8 GHz was 125 (decreasing 14 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 132.7. The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.0). Three hour interval K indices: 32223223 (planetary), 34343323 (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: 215) and 11 active regions using 1K resolution (SN: 163) SDO images on the visible solar disk.

Region 12149 [N09W62] decayed slowly but could still produce a minor M class flare.
Region 12150 [S13W58] was quiet and stable.
Region 12151 [S07W47] was quiet and stable.
Region 12152 [S15E02] developed at a slower rate than on the previous days. An M class flare is still possible.
Region 12153 [S10W24] developed slowly and quietly.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3774 [N06W07] reemerged with penumbra spots.
S3776 [N09E22] reemerged with penumbra spots.
S3779 [N10E08] reemerged with a penumbra spot.
S3781 [S07E64] decayed slowly and quietly.
New region S3783 [S17E45] emerged with penumbra spots.
New region S3784 [S28E11] was observed with penumbra spots.
New region S3785 [N26W29] emerged with a penumbra spot.

An active region a few days behind the northeast limb produced a large flare at 11:05 UTC, the flare was associated with a massive CME and enhanced proton flux levels.

C2+ Flares (GOES):

Magnitude Peak time (UTC) Location AR
C2.1 07:44   12149

Coronal mass ejections (CMEs)

August 30 - September 1: 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]

A recurrent southern hemisphere coronal hole (CH633) apparently closed on September 1 due to the activity in AR 12152.

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 fair.

Forecast

The geomagnetic field is expected to be quiet on September 2-4.

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
12149 2014.08.21 5 9 5 N09W77 0230 DAC DAC

 

12150 2014.08.22 1 1 1 S13W60 0060 HSX HSX area: 0090
12151 2014.08.22
2014.08.23
1 6 4 S07W48 0100 HSX CSO area: 0180
S3764 2014.08.25       N03W52           plage
S3765 2014.08.26       N13W24           plage
12153 2014.08.26
2014.08.29
5 13 8 S10W24 0030 CAO DAO area: 0090
12152 2014.08.26
2014.08.28
32 48 28 S16E01 0220 DAC EAC

area: 0400

S3768 2014.08.26       N18W58         plage
S3772 2014.08.29       S07W11           plage
S3774 2014.08.29   5 2 N06W07 0012   BXO    
S3776 2014.08.30   5 1 N09E22 0010   AXX    
S3778 2014.08.30       S13W29           plage
S3779 2014.08.30   1 1 N10E08     AXX    
S3781 2014.08.31   1   S07E62 0001   AXX  
S3782 2014.08.31       N22E10         plage
S3783 2014.09.01   3 1 S17E45 0007   BXO    
S3784 2014.09.01   2 1 S28E11 0005   AXX    
S3785 2014.09.01   1 1 N26W29 0003   AXX    
Total spot count: 44 95 53  
Sunspot number: 94 215 163  (total spot count + 10 * number of spotted regions)
Weighted SN: 69 120 88  (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): 56 75 90 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 (79.8 projected, +1.4) 4.88
2014.04 143.9 144.8 84.7 (79.2 projected, -0.6) 7.88
2014.05 129.7 132.9 75.2 (76.6 projected, -2.6) 5.75
2014.06 122.0 125.8 71.0 (74.0 projected, -2.6) 6.72
2014.07 137.4 141.8 72.5 (71.0 projected, -3.0) 4.50
2014.08 124.6   74.7 (67.5 projected, -3.5) 7.7
2014.09 125 (1)   3.1 (2A) / 94 (2B) / 72.3 (2C) (63.3 projected, -4.2) (9.0)

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.