Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 25, 2014 at 04:50 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update August 1, 2014)] [Cycle 24 progress (last update August 13, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update August 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update August 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 very quiet on August 24. Solar wind speed at SOHO ranged between 273 and 308 km/s.

Solar flux at 20h UTC on 2.8 GHz was 141 (increasing 8.8 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 130.9. The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 1.6). Three hour interval K indices: 10001000 (planetary), 01121111 (Boulder).

The background x-ray flux is at the class B5 level.

At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 210) and 10 active regions using 1K resolution (SN: 158) SDO images on the visible solar disk.

Region 12141 [N17W76] decayed slowly and quietly.
Region 12142 [N10W74] was mostly quiet and stable.
Region 12143 [S04W80] decayed slowly and was mostly quiet.
Region 12146 [N08W30] developed further becoming a compact region with most spots inside a large penumbra. An M class flare is possible.
Region 12147 [S11W22] decayed slowly and quietly.
Region 12148 [N07W13] decayed slowly and lost all trailing umbrae.
Region 12149 [N10E33] decayed in the trailing spot section slowly losing the magnetic delta structure. The leading penumbra increased its area.
Region 12150 [S13E48] was quiet and stable.
Region 12151 [S07E60] produced a major flare and was otherwise mostly quiet and unchanged.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3759 [N13W34] decayed slowly and quietly.
New region S3762 [N18W33] emerged with penumbra spots.

C2+ Flares (GOES):

Magnitude Peak time (UTC) Location AR
C5.5/1N 05:02 N12E45 12149
C2.8 07:40 S04W69 12143
M5.9/2B 12:17 S06E71 12151
C2.2 19:23   12142

Coronal mass ejections (CMEs)

August 22-23: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
August 24: A wide CME was observed after the M5 event in AR 12151. While the core of the CME is not Earth directed, there is a slight chance of a solar wind shock on August 27.

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 August 25-27.

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
12143 2014.08.13
2014.08.14
6 4 4 S04W80 0070 CAO CAO  
12142 2014.08.13
2014.08.14
3 4 2 N09W77 0030 CAO CRO  
12141 2014.08.13
2014.08.14
1 2 1 N17W76 0040 HSX HAX  
12146 2014.08.16 10 21 13 N09W33 0280 DKI DKC

beta-delta

location: N08W30

12147 2014.08.17   3 1 S08W24 0006   BXO location: S11W22
S3746 2014.08.18       N20W36           plage
S3747 2014.08.18       N13W40           plage
12148 2014.08.19
2014.08.20
10 29 16 N07W13 0050 CAO CAO  
12149 2014.08.21 16 26 16 N11E35 0190 EAC EAI beta-gamma

location: N10E33

S3755 2014.08.21       N13W52           plage
12150 2014.08.22 1 3 1 S13E46 0120 HSX CSO area: 0220
12151 2014.08.22
2014.08.23
1 3 2 S07E58 0110 HAX CSO area: 0180
S3759 2014.08.23   3 2 N13W34 0008   CRO  
S3760 2014.08.23       S16W16         plage
S3761 2014.08.23       S42W18         plage
S3762 2014.08.24   2   N18W33 0003   BXO    
Total spot count: 48 100 58  
Sunspot number: 128 210 158  (total spot count + 10 * number of spotted regions)
Weighted SN: 93 146 104  (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): 77 74 87 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
2013.04 124.8 125.9 72.4 57.9 (+0.4) 5.40
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) (78.1 projected, +0.8) 10.70
2014.03 149.9 148.5 91.9 (79.0 projected, +0.9) 4.88
2014.04 143.9 144.8 84.7 (78.1 projected, -0.9) 7.88
2014.05 129.7 132.9 75.2 (75.6 projected, -2.5) 5.75
2014.06 122.0 125.8 71.0 (72.9 projected, -2.7) 6.72
2014.07 137.4 141.8 72.5 (69.9 projected, -3.0) 4.50
2014.08 124.6 (1)   87.5 (2A) / 113.0 (2B) / 80.6 (2C) (66.5 projected, -3.4) (6.0)

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.