Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 7, 2013 at 04:25 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 September 5, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated September 24, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was very quiet on October 6. Solar wind speed at SOHO ranged between 270 and 335 km/s. A weak disturbance began after 01h UTC on October 7.

Solar flux measured at 20h UTC on 2.8 GHz was 106.5 (increasing 12.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 112.1. The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.0). Three hour interval K indices: 00000001 (planetary), 00012211 (Boulder).

The background x-ray flux was at the class B3 level.

At the time of counting spots (see image time) spots were observed in 9 active regions in 2K resolution (SN: 141) and 9 active regions in 1K resolution (SN: 114) SDO images on the visible solar disk.

Region 11855 [S13W69] decayed further and was quiet.
Region 11856 [N08E17] decayed slowly and quietly.
Region 11857 [S07E17] was quiet and stable.
Region 11859 [S15W36] was quiet and stable.

Spotted regions not numbered by SWPC:
S2729 [S13W21] reemerged with penumbra spots.
S2733 [S23W07] developed slowly and quietly.
New region S2735 [S11E74] rotated into view.
New region S2736 [S28E56] emerged with several spots.
New region S2737 [S17E46] emerged with penumbra spots.

Coronal mass ejections (CMEs)

October 4-6: 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 will rotate into an Earth facing position on October 5-7.

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 to unsettled on October 7. Effects from CH589 could cause a few unsettled intervals on October 8-9 and unsettled to active conditions on October 10.

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
11854 2013.09.27
2013.09.28
      N05W54           plage

location: N07W45

11855 2013.09.28
2013.09.30
7 2 2 S13W67 0040 CAO HRX

location: S13W69

area: 0020

11857 2013.10.01
2013.10.02
1 3 1 S08E14 0110 HSX CSO area: 0180

location: S07E17

11856 2013.10.01
2013.10.02
4 16 7 N08E18 0040 CAO CRO  
S2729 2013.10.02   2 2 S13W21 0009   AXX   plage
S2730 2013.10.02       N11W34           plage
11859 2013.10.02
2013.10.04
1 3 2 S15W37 0010 AXX AXX  
S2732 2013.10.03       S25E24           plage
S2733 2013.10.03   15 5 S23W07 0040   CRO  
S2734 2013.10.04       N24W07           plage
S2735 2013.10.06   2 2 S11E74 0020   BXO    
S2736 2013.10.06   4 2 S28E56 0017   DRO    
S2737 2013.10.06   4 1 S17E46 0014   BXO    
Total spot count: 13 51 24  
Sunspot number: 53 141 114  (total spot count + 10 * number of spotted regions)
Weighted SN: 28 68 41  (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): 32 49 63 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) 5.29
2013.10  108.4 (1) 12.1 (2A) / 62.5 (2B) / 38.9 (2C) (53.9 projected, -1.5) (10.4)

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.