Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 24, 2013 at 06:30 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 August 20, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to active on August 23. Solar wind speed at SOHO ranged between 443 and 545 km/s under the influence of CME effects.

Solar flux measured at 20h UTC on 2.8 GHz was 124.1 (increasing 16.2 over the last solar rotation). The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.0). Three hour interval K indices: 43332222 (planetary), 43333232 (Boulder).

The background x-ray flux was at the class B4 level.

At midnight UTC the visible solar disk had 16 spotted active regions (in 2K resolution SDO images).

Region 11820 [S13W71] decayed slowly and quietly.
Region 11823 [S07W35] decayed slowly and quietly.
Region 11825 [N15W82] was quiet and stable.
Region 11827 [S18E07] decayed slowly and quietly.
Region 11828 [N15E15] decayed slowly and quietly.
Region 11830 [S06W67] was quiet and stable.
Region 11831 [N12W63] decayed slowly and quietly.
Region 11832 [N24W62] decayed quickly and quietly.
New region 11833 [N19E06] emerged on August 22 and decayed on August 23 when it was numbered by SWPC.

Spotted regions not numbered by SWPC:
S2611 [S10W03] was quiet and stable.
S2623 [S19W12] reemerged with penumbra spots.
S2628 [S05W59] was quiet and stable.
New region S2629 [N07E51] emerged with a penumbra spot.
New region S2630 [N07E10] emerged with two spots.
New region S2631 [N13E81] rotated into view with penumbra spots.
New region S2632 [S18W31] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

August 21-23: 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 trans equatorial coronal hole (CH581) was in an Earth facing position on August 22.

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 fair to good.

Forecast

The geomagnetic field is expected to be quiet to unsettled on August 24-26 with a chance of active intervals on August 25-26 due to effects from CH581.

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
11820 2013.08.11
2013.08.13
3 3 1 S12W73 0070 CAO DAO  
11823 2013.08.14
2013.08.15
1 3 1 S06W37 0100 HSX CSO

area: 0170

11822 2013.08.15       S11W56           plage
S2608 2013.08.16       S21W59           plage
11827 2013.08.17
2013.08.18
8 16 4 S18E05 0030 CRO DRO  
S2611 2013.08.17   3   S10W03 0004   AXX  
11826 2013.08.17
2013.08.18
      N13W55           plage, SWPC/USAF moved this region to the location of AR S2617

real location: N08W47

11825 2013.08.17
2013.08.18
1 2 1 N15W86 0030 HAX CSO  
11828 2013.08.18
2013.08.19
3 16 4 N15E15 0020 CRO CRO area: 0030
S2617 2013.08.18       N14W49           plage
S2621 2013.08.19       N20E10           plage
S2622 2013.08.19       S28W54           plage
S2623 2013.08.20   6   S19W12 0008   BXO    
11831 2013.08.20
2013.08.21
7 9 6 N14W63 0060 DAO DSO area: 0120
11832 2013.08.20
2013.08.21
6 5 3 N25W61 0030 CRO BXO  
11829 2013.08.20
2013.08.21
      N05W89         plage
11830 2013.08.21 5 6 3 S05W64 0070 DAO DSO location: S06W67
11833 2013.08.22
2013.08.23
3 2   N18E07 0010 BXO AXX area: 0006
S2628 2013.08.22   4 2 S05W59 0030   CRO  
S2629 2013.08.23   1   N07E51 0002   AXX    
S2630 2013.08.23   2 2 N07E10 0010   CRO    
S2631 2013.08.23   2   N13E81 0006   AXX    
S2632 2013.08.23   1   S18W31 0001   AXX    
Total spot count: 37 81 27  
Sunspot number: 127 241 127  (total spot count + 10 * number of spotted regions)
Weighted SN: 71 118 64  (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): 76 84 70 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
2013.08 116.1 (1) 75.3 (2A) / 101.4 (2B) / 62.6 (2C) (57.6 projected, -0.1) (7.98)

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.