Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 11, 2013 at 04:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update October 1, 2013)] [Cycle 24 progress (last update October 1, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update October 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update October 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update October 9, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated October 10, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to active on October 10. Solar wind speed at SOHO ranged between 442 and 526 km/s under the influence of CME effects.

Solar flux measured at 20h UTC on 2.8 GHz was 120.7 (increasing 28.6 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 111.8. The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.5). Three hour interval K indices: 43221111 (planetary), 34221102 (Boulder).

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

At the time of counting spots (see image time) spots were observed in 10 active regions in 2K resolution (SN: 235) and 9 active regions in 1K resolution (SN: 151) SDO images on the visible solar disk.

Region 11856 [N06W36] decayed slowly and quietly.
Region 11857 [S08W37] was quiet and stable.
Region 11861 [S10E22] developed quickly and has magnetic delta structures in both the largest leading and trailing penumbrae. M class flares are likely and further development will make even X class flares possible.
Region 11862 [S23W60] developed slowly and quietly.
Region 11863 [S19W07] developed slowly and quietly.
Region 11864 [S23E42] was generally unchanged and features a magnetic delta structure in the trailing spot section. M class flaring is possible.

New region 11867 [N22E08] emerged on October 9 and was numbered by SWPC the next day.

Spotted regions not numbered by SWPC:
New region S2745 [N05E28] emerged slowly and quietly.
New region S2746 [S25E23] emerged with a penumbra spot.
New region S2747 [S20W69] emerged with several spots.

Coronal mass ejections (CMEs)

October 8: A partial halo CME was observed after a filament eruption late in the day. There's a small chance of this CME reaching Earth on October 11 or 12.
October 9-10
: 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 (CH589) in the northern hemisphere was in an Earth facing position on October 5-8. A recurrent trans equatorial coronal hole (CH590) will rotate into an Earth facing position on October 11.

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 to unsettled on October 11 and quiet on October 12-13. Effects from CH590 could cause some unsettled and active intervals on October 14-15.

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
11857 2013.10.01
2013.10.02
1 9 3 S08W37 0100 HSX CSO area: 0170

 

11856 2013.10.01
2013.10.02
2 7 3 N07W36 0010 BXO AXX  
11866 2013.10.02
2013.10.09
      S16W77         plage
S2732 2013.10.03       S25W29           plage
11862 2013.10.03
2013.10.07
8 12 5 S23W61 0040 DAO CRO

 

S2734 2013.10.04       N24W59           plage
11861 2013.10.06
2013.10.07
23 51 17 S10E22 0200 EAC EAC gamma-delta

area: 0450

11860 2013.10.06
2013.10.07
      S28W01           plage
11863 2013.10.06
2013.10.08
5 14 9 S19W08 0030 DRO DRO  
11864 2013.10.07
2013.10.08
2 28 17 S23E34 0060 HAX FAC beta-gamma-delta

area: 0400

location: S23E42

11865 2013.10.08 15     S22E45 0220 DAI       part of AR 11864
S2739 2013.10.07       N17W42           plage
S2740 2013.10.08       N05W08           plage
11867 2013.10.09
2013.10.10
2 4 2 N23E07 0010 AXX CRO  
S2743 2013.10.09       S12E02         plage
S2744 2013.10.09       S26W27         plage
S2745 2013.10.10   4 2 N05E28 0014   CRO    
S2746 2013.10.10   1   S25E23 0001   AXX    
S2747 2013.10.10   5 3 S20W69 0020   BXO    
Total spot count: 58 135 61  
Sunspot number: 138 235 151  (total spot count + 10 * number of spotted regions)
Weighted SN: 51 119 69  (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): 83 82 83 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
2012.06 119.6 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 58.4 (-0.3) 6.11
2013.03 111.3 57.9 57.5 (-0.9) 10.56
2013.04 124.8 72.4 (56.2 projected, -1.3) 5.40
2013.05 131.4 78.7 (55.8 projected, -0.4) 9.73
2013.06 110.1 52.5 (56.0 projected, +0.2) 12.60
2013.07 115.5 57.0 (56.1 projected, +0.1) 9.47
2013.08 114.6 66.0 (55.9 projected, -0.2) 8.27
2013.09 102.6 36.9 (55.4 projected, -0.5) 5.23
2013.10  110.8 (1) 26.6 (2A) / 79.9 (2B) / 45.5 (2C) (53.9 projected, -1.5) (12.35)

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.