Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 11, 2013 at 05:30 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 10. Solar wind speed at SOHO ranged between 364 and 461 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 102.5 (decreasing 10.4 over the last solar rotation). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.0). Three hour interval K indices: 11122011 (planetary), 22222221 (Boulder).

The background x-ray flux was at the class B2 level.

At midnight UTC the visible solar disk had 8 spotted active regions (in 2K resolution SDO images).

Region 11809 [N11W67] decayed slowly and quietly.
Region 11813 [S13W46] decayed losing all umbrae.
Region 11814 [S26E22] was quiet and stable.
Region 11816 [S20E21] decayed slowly and quietly.
New region 11817 [S22E36] rotated into view on August 8 and was numbered by SWPC 2 days later. The region developed on August 10 and has minor polarity intermixing. Further C class flaring is possible.
New region 11818 [S07E61] rotated into view on August 9 and got its NOAA number the next day.
New region 11819 [S19E51] emerged on August 9 and was numbered by SWPC the next day.

Spotted regions not numbered by SWPC:
New region S2597 [S21W20] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

August 8-10: 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 coronal hole (CH579) in the northern hemisphere will likely rotate into an Earth facing position on August 11-14.

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

Forecast

The geomagnetic field is expected to be quiet on August 11-13. A high speed stream from CH579 could cause quiet to minor storm conditions on August 14-17.

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
11809 2013.07.30 2 4 2 N10W67 0020 HRX BXO

 

11810 2013.07.31       S24W62         plage
S2585 2013.08.03       N13W43           plage
S2586 2013.08.03       N17W28           plage
S2587 2013.08.03       N24W42           plage
11813 2013.08.04
2013.08.07
8 11 4 S14W47 0030 CRO BXO  
11814 2013.08.06
2013.08.07
1 2 1 S26E22 0020 HAX HAX area: 0050
11816 2013.08.06
2013.08.07
  2 1 S22E20 0008   BXO  
S2593 2013.08.06       S12W59           plage
11815 2013.08.07       N08W86           plage
11817 2013.08.08
2013.08.10
3 17 5 S22E34 0017 CRO CRI beta-gamma

area: 0090

11819 2013.08.09
2013.08.10
1 1 1 S20E49 0010 AXX HRX area: 0015
11818 2013.08.09
2013.08.10
1 8 3 S07E58 0020 HRX CAO beta-gamma

area: 0100

S2596 2013.08.10   1   S21W20 0001   AXX    
Total spot count: 16 46 17  
Sunspot number: 76 126 87  (total spot count + 10 * number of spotted regions)
Weighted SN: 33 62 33  (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): 46 44 48 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
2013.08 106.1 (1) 26.3 (2A) / 81.5 (2B) / 52.1 (2C) (57.6 projected, -0.1) (6.25)

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.