Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 14, 2013 at 05:20 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 very quiet on October 13. Solar wind speed at SOHO ranged between 288 and 353 km/s. Solar wind speed is increasing early on Oct.14, most likely due to the arrival of a stream from CH590.

Solar flux measured at 20h UTC on 2.8 GHz was 129.3 (increasing 34.8 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 112.2. 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: 10000011 (planetary), 10001200 (Boulder).

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

At the time of counting spots (see image time) spots were observed in 14 active regions in 2K resolution (SN: 237) and 10 active regions in 1K resolution (SN: 148) SDO images on the visible solar disk.

Region 11857 [S08W77] was quiet and stable.
Region 11860 [S29W35] reemerged with a penumbra spot.
Region 11861 [S09W18] was mostly unchanged. An M class flare is still possible.
Region 11863 [S19W48] developed slowly and quietly.
Region 11864 [S23E03] decayed slowly. Another M class flare is possible.
C5+ flare: M1.7 at 00:43 UTC.
Region 11867 [N22W29] was quiet and stable.
New region 11868 [N18E49] rotated into view on October 11 and was numbered by SWPC 2 days later.
New region 11869 [N18E67] rotated into view on October 12 and got its NOAA number the next day.

Spotted regions not numbered by SWPC:
S2740 [N03W52] decayed slowly and quietly.
S2745 [N04W11] reemerged with penumbra spots.
New region S2753 [N17E77] rotated into view. The leading polarity area is close to the trailing spots of AR 11869.

Coronal mass ejections (CMEs)

October 11-12: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
October 13: A partial halo CME was observed after an M1 flare in AR 11864 early in the day. There is a 20-30% chance the CME could reach Earth late on October 15 or on October 16.

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 trans equatorial coronal hole (CH590) was in an Earth facing position on October 11-12.

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

Forecast

The geomagnetic field is expected to be quiet to active on October 14-15 due to effects from CH590. If the CME observed early on October 13 reaches Earth, unsettled and active intervals will be possible on October 16, otherwise quiet conditions are likely.

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 1 1 S08W78 0070 HSX HSX  

 

11856 2013.10.01
2013.10.02
      N07W81           plage
11861 2013.10.06
2013.10.07
12 22 9 S09W19 0400 DHI DHI

area: 0540

11860 2013.10.06
2013.10.07
  1   S28W43 0003   AXX   location: S29W35
11863 2013.10.06
2013.10.08
4 6 4 S18W50 0020 CRO DRO area: 0040
11864 2013.10.07
2013.10.08
1 27 15 S23W07 0060 HSX FAC beta-gamma-delta

area: 0280

location: S23E03

11865 2013.10.08 16     S22E06 0270 DKC       part of AR 11864
S2740 2013.10.08   2   N03W52 0003   BXO  
11867 2013.10.09
2013.10.10
7 19 10 N24W32 0050 DAO DRO  
S2743 2013.10.09       S12W37           plage
S2745 2013.10.10   2 1 N04W11     BXO    
S2746 2013.10.10       S25W16         plage
11868 2013.10.11
2013.10.13
1 1 1 N18E51 0010 AXX HRX  
S2751 2013.10.11       N24E02           plage
11869 2013.10.12
2013.10.13
3 3 2 N19E66 0040 DSO CRO  
S2753 2013.10.13   3 2 N17E77 0040   CAO    
S2754 2013.10.13   1   N23E05 0003   AXX    
S2755 2013.10.13   7 3 S14E08 0025   DRO    
S2756 2013.10.13   2   S08E57 0002   BXO    
Total spot count: 45 97 48  
Sunspot number: 125 237 148  (total spot count + 10 * number of spotted regions)
Weighted SN: 88 137 88  (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): 75 83 81 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  114.9 (1) 36.9 (2A) / 88.1 (2B) / 49.4 (2C) (53.9 projected, -1.5) (10.27)

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.