Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 18, 2013 at 06:40 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, 2013)] [Cycle 24 progress (last update August 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update August 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update August 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update August 4, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated July 28, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet on August 17. Solar wind speed at SOHO ranged between 558 and 734 km/s under the influence of a high speed stream from CH579, slowly decreasing all day.

Solar flux measured at 17h UTC on 2.8 GHz was 123.2 (increasing 13.8 over the last solar rotation, the measurements at 20 and 23h UTC were both influenced by the LDE in AR 11818). 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: 22212112 (planetary), 22322222 (Boulder).

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

At midnight UTC the visible solar disk had 13 spotted active regions (in 2K resolution SDO images).

Region 11817 [S21W60] decayed slowly and quietly. The region has a magnetically simple spot layout.
Region 11818 [S06W33] has all umbrae within a single penumbral structure. Further M class flares are possible as long as the magnetic delta structure in the northern part remains. C5+ events: M3.3/2B at 18:24 and a long duration M1.4 event peaking at 19:33 UTC. An asymmetric full halo CME was observed in LASCO imagery after these events.
Region 11820 [S14E08] decayed slowly and quietly.
Region 11822 [S07E31] decayed slowly and quietly.
Region 11823 [S07E45] was quiet and stable.
New region 11824 [S15W12] emerged quickly and could produce C flares.

Spotted regions not numbered by SWPC:
S2601 [S19E19] was quiet and stable.
New region S2610 [S19E83] rotated into view.
New region S2611 [S10E78] rotated into view with a penumbra spot.
New region S2612 [N07E36] emerged with umbra forming in one spot.
New region S2613 [N25E18] emerged with a penumbra spot.
New region S2614 [S16W23] emerged with penumbra spots.
New region S2615 [N15E03] emerged with several penumbra spots.

Coronal mass ejections (CMEs)

August 15-16: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
August 17: An asymmtric full halo CME was observed after the M class events in AR 11818. The CME could reach Earth on August 19 or on August 20.

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 coronal hole (CH579) in the northern hemisphere rotated across the central meridian on August 11-15. A recurrent trans equatorial coronal hole (CH580) will rotate into an Earth facing position on August 18-19.

Coronal hole map

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and 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 with a chance of unsettled intervals on August 18-19 due to effects from CH579. The halo CME observed on August 17 could reach Earth either late on August 19 or on August 20 and cause unsettled to minor storm conditions. Quiet to active conditions are likely on August 21-22 as a high speed stream from CH580 becomes geoeffective.

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: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% 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 STAR SDO SWPC STAR Current Previous
2K 1K
11814 2013.08.06
2013.08.07
      S27W74           plage
11816 2013.08.06
2013.08.07
      S22W77           plage
11817 2013.08.08
2013.08.10
8 10 5 S21W57 0150 ESO CAO location: S21W60
11819 2013.08.09
2013.08.10
      S16W46         plage
11818 2013.08.09
2013.08.10
13 21 6 S07W33 0300 DKO DKC beta-delta
11820 2013.08.11
2013.08.13
5 19 6 S13E10 0010 BXO BXO  
S2599 2013.08.12       N20W23           plage
S2601 2013.08.13   7 1 S19E19 0012   BXO  
S2602 2013.08.13       N20W03         images\AR_S2602_20130816_2345.jpg  
11821 2013.08.14       N01W65           plage
11823 2013.08.14
2013.08.15
1 3 1 S07E43 0120 HSX CSO area: 0170
S2605 2013.08.14       S22W31           plage
11822 2013.08.15 3 5 4 S08E30 0010 BXO BXO area: 0020
S2606 2013.08.15       N14W39           plage
S2608 2013.08.16       S21E19         plage
S2609 2013.08.16       S29W02         plage
11824 2013.08.17 6 15 6 S14W13 0040 DAO DAO   area: 0200
S2610 2013.08.17   2 1 S19E83 0100   HAX    
S2611 2013.08.17   1   S10E78 0003   AXX    
S2612 2013.08.17   2 1 N07E36 0012   CRO    
S2613 2013.08.17   2 1 N25E18 0007   AXX    
S2614 2013.08.17   3   S16W33 0007   AXX    
S2615 2013.08.17   6 2 N15E03 0014   BXO    
Total spot count: 36 96 34  
Sunspot number: 96 226 144  (total spot count + 10 * number of spotted regions)
Weighted SN: 61 129 67  (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): 62 60 56 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
2011.11 153.5 (cycle peak) 96.7 (cycle peak) 61.1 (+1.2) 5.55
2012.02 106.5 32.9 66.9 (+1.4)
likely cycle 24 max
8.81
2012.05 121.5 69.0 61.7 (-2.9) 7.06
2012.06 119.6 64.5 58.9 (-2.8) 10.08
2012.07 133.9 66.5 57.8 (-1.1) 13.90
2012.08 115.4 63.0 58.2 (+0.4) 7.96
2012.09 122.9 61.4 58.1 (-0.1) 8.07
2012.10 123.3 53.3 58.6 (+0.5) 9.97
2012.11 121.3 61.8 59.7 (+1.1) 7.08
2012.12 108.6 40.8 59.6 (-0.1) 3.44
2013.01 127.1 62.9 58.7 (-0.9) 4.69
2013.02 104.3 38.0 (57.8 projected, -0.9) 6.11
2013.03 111.3 57.9 (57.3 projected, -0.5) 10.56
2013.04 124.8 72.4 (57.3 projected, 0.0) 5.40
2013.05 131.4 78.7 (57.3 projected, 0.0) 9.73
2013.06 110.1 52.5 (57.6 projected, +0.3) 12.60
2013.07 115.5 57.0 (57.7 projected, +0.1) 9.47
2013.08 111.7 (1) 49.1 (2A) / 89.5 (2B) / 53.8 (2C) (57.6 projected, -0.1) (7.71)

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 SIDC 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 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.