Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 2, 2014 at 05:10 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, 2014)] [Cycle 24 progress (last update October 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update October 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update October 1, 2014)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update September 6, 2014)]

[New: Noon SDO count 1K 4K (large file)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated September 6, 2014]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was quiet to unsettled on October 1. Solar wind speed at SOHO ranged between 350 and 438 km/s, weakly under the influence of a low speed stream from CH637.

Solar flux at 20h UTC on 2.8 GHz was 155 (increasing 9.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 138.2. 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: 32222212 (planetary), 33333321 (Boulder).

The background x-ray flux is at the class C1 level.

At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 265) and 15 active regions using 1K resolution (SN: 215) SDO images on the visible solar disk.

Region 12172 [S11W72] decayed slowly. There's a minor chance of an M class flare.
Region 12173 [S15W75] developed in the trailing spot section while the leading spots disappeared. C and minor M class flaring is possible.
Region 12175 [N17W84] decayed further and may still be capable of M class flaring as the region rotates over the northwest limb.
Region 12176 [N08W38] developed slowly and quietly.
Region 12177 [N12E02] decayed slowly and quietly.
Region 12178 [S02E19] decayed in the trailing spot section. C and minor M class flares are possible.
Region 12179 [S10E31] was quiet and stable.
Region 12181 [S10E10] decayed slowly and quietly.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3848 [S16W13] was quiet and stable.
S3858 [N05E32] was quiet and stable.
S3861 [N12E09] was quiet and stable.
S3866 [S04E32] was quiet and stable.
New region S3869 [S13E54] emerged with penumbra spots.
New region S3870 [N13E82] rotated into view.
New region S3871 [S32E15] emerged with a penumbra spot.

C2+ flares (GOES):

Magnitude Peak time (UTC) Location AR Comment
C6.7 (LDE) 03:06 S12W64 12172  

Coronal mass ejections (CMEs)

September 29 - October 1: 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 small southern hemisphere coronal hole (CH637) was in an Earth facing position on September 28.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over 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 2-4.

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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% 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 Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12173 2014.09.19
2014.09.20
12 9 5 S14W79 0100 DAI DAO

location: S15W75

12172 2014.09.20 13 13 5 S09W69 0200 FAO FKO

location: S11W72

area: 0500

12175 2014.09.21
2014.09.25
3 3 2 N18W90 0140 DAO DAO

location: N17W84

12176 2014.09.22
2014.09.25
7 10 4 N09W39 0020 CRO CAO area: 0050
12177 2014.09.25 19 21 14 N12E03 0070 DAO DAO

 

S3848 2014.09.25   2 2 S16W13 0006   AXX  
S3850 2014.09.26       S16W40           plage
12178 2014.09.27 12 22 13 S02E19 0180 DAC DSC area: 0320
12179 2014.09.27
2014.09.28
1 9 3 S11E29 0040 HAX CAO area: 0070

location: S10E31

S3858 2014.09.27   3 2 N05E32 0008   BXO  
S3859 2014.09.27       N11W13           plage
S3860 2014.09.27       S00W57           plage
S3861 2014.09.27   5 4 N12E09 0014   BXO  
12181 2014.09.28
2014.09.30
5 7 4 S12E10 0010 BXO CRO location: S10E10
S3863 2014.09.28       S18W31           plage
S3864 2014.09.29       S07W21           plage
S3866 2014.09.29   6 3 S04E32 0012   AXX  
12180 2014.09.29
2014.09.30
2     N13W27 0010 BXO     spotless
S3868 2014.09.30       S24E03         plage
S3869 2014.10.01   4 2 S13E54 0016   CRO    
S3870 2014.10.01   1 1 N13E82 0006   HRX    
S3871 2014.10.01   1 1 S32E15 0004   AXX    
Total spot count: 74 115 65  
Sunspot number: 164 265 215  (total spot count + 10 * number of spotted regions)
Weighted SN: 107 164 114  (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): 98 93 118 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number Average ap
(3)
Measured 1 AU
2013.06 110.1 113.7 52.5 62.6 (+2.7) 12.60
2013.07 115.5 119.3 57.0 65.5 (+2.9) 9.47
2013.08 114.6 118.3 66.0 69.0 (+3.5) 8.27
2013.09 102.6 103.7 36.9 73.1 (+4.1) 5.23
2013.10  132.1 131.2 85.6 75.0 (+1.9) 7.71
2013.11  148.3 145.1 77.6 75.4 (+0.4) 5.68
2013.12 147.7 143.1 90.3 76.0 (+0.6) 4.68
2014.01 157.4 152.4 81.8 77.3 (+1.3) 5.44
2014.02 170.3
(cycle peak)
166.3 102.3 (cycle peak) 78.4 (+1.1) 10.70
2014.03 149.9 148.5 91.9 80.8 (+2.4) 4.88
2014.04 143.9 144.8 84.7 (82.7 projected, +1.9) 7.88
2014.05 129.7 132.9 75.2 (82.3 projected, -0.4) 5.75
2014.06 122.0 125.8 71.0 (81.1 projected, -1.2) 6.72
2014.07 137.4 141.8 72.5 (79.4 projected, -1.7) 4.50
2014.08 124.7 127.9 74.7 (77.1 projected, -2.3) 7.71
2014.09 146.2   87.6 (73.8 projected, -3.3) 9.6
2014.10 155 (1)   5.3 (2A) / 164 (2B) / 96.4 (2C) (71.4 projected, -2.4) (8.5)

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 WDC-SILSO 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 GFZ 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.