Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 1, 2014 at 04:15 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 active on September 30. Solar wind speed at SOHO ranged between 347 and 418 km/s.

Solar flux at 20h UTC on 2.8 GHz was 162 (increasing 24.3 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 138.5. The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.6). Three hour interval K indices: 34232222 (planetary), 23343222 (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: 308) and 13 active regions using 1K resolution (SN: 208) SDO images on the visible solar disk.

Region 12171 [S10W74] rotated partly out of view.
Region 12172 [S11W59] decayed slowly. An M class flare is still possible.
Region 12173 [S16W65] decayed quickly and was mostly quiet.
Region 12175 [N16W75] decayed as the leading penumbra fragmented. There is still a small magnetic delta structure in a central penumbra. An M class flare is still possible.
Region 12176 [N07W24] developed slowly and quietly.
Region 12177 [N12E16] lost penumbral area and was quiet.
Region 12178 [S02E33] developed significantly in the trailing spot section with a magnetic delta structure forming. An M class flare is possible.
Region 12179 [S10E45] was quiet and stable.
New region 12180 [N12W10] emerged on September 29 and was numbered by SWPC the next day.
New region 12181 [S11E25] emerged on September 28 with SWPC numbering the region 2 days later.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3848 [S15W01] reemerged with penumbra spots.
S3858 [N04E44] was quiet and stable.
S3861 [N12E22] was quiet and stable.
S3866 [S04E46] was quiet and stable.
New region S3868 [S24E16] emerged with a penumbra spot.

C2+ flares (GOES):

Magnitude Peak time (UTC) Location AR Comment
C2.6 04:44 S15W56 12173  

Coronal mass ejections (CMEs)

September 28-30: 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 fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on October 1-3.

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
12171 2014.09.18
2014.09.19
1 1 1 S06W83 0040 HSX AXX location: S10W74

area: 0005

12173 2014.09.19
2014.09.20
9 28 9 S14W66 0100 EAI EAI

location: S16W65

12172 2014.09.20 14 22 11 S10W57 0320 FKC FKO

location: S11W59

area: 0600

12175 2014.09.21
2014.09.25
11 13 7 N17W79 0450 EKC DKC beta-delta

location: N16W75

12176 2014.09.22
2014.09.25
3 5 5 N08W25 0030 DRO DRO  
12177 2014.09.25 19 35 15 N12E16 0140 EAC DAC

 

S3848 2014.09.25   3   S15W01 0006   BXO    
S3850 2014.09.26       S16W27           plage
S3851 2014.09.26       N10W55           plage
12178 2014.09.27 5 17 12 S03E32 0120 DAO DAC area: 0350

location: S02E33

12179 2014.09.27
2014.09.28
1 3 2 S10E45 0030 HAX HSX area: 0080
S3858 2014.09.27   1   N04E44 0001   AXX  
S3859 2014.09.27       N11W00           plage
S3860 2014.09.27       S00W44           plage
S3861 2014.09.27   9 5 N12E22 0030   DRO  
12181 2014.09.28
2014.09.30
1 12 4 S09E23 0010 HRX CRO  
S3863 2014.09.28       S18W18         plage
S3864 2014.09.29       S07W08         plage
S3866 2014.09.29   1 1 S04E46 0005   AXX  
12180 2014.09.29
2014.09.30
2 7 5 N12W13 0010 BXO BXO location: N12W10

area: 0020

S3868 2014.09.30   1 1 S24E16 0003   AXX    
Total spot count: 66 158 78  
Sunspot number: 166 308 208  (total spot count + 10 * number of spotted regions)
Weighted SN: 117 207 127  (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): 100 108 114 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
2013.05 131.4 134.3 78.7 59.9 (+2.0) 9.73
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 (80.3 projected, +1.9) 4.88
2014.04 143.9 144.8 84.7 (81.0 projected, +0.7) 7.88
2014.05 129.7 132.9 75.2 (79.2 projected, -1.8) 5.75
2014.06 122.0 125.8 71.0 (76.6 projected, -2.6) 6.72
2014.07 137.4 141.8 72.5 (73.6 projected, -3.0) 4.50
2014.08 124.7 127.9 74.7 (70.1 projected, -3.5) 7.71
2014.09 146.2 (1)   130.0 (2A/2B) / 95.4 (2C) (65.9 projected, -4.2) (9.6)

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.