Solar Terrestrial Activity Report

Activity chart

Last major update issued on September 23, 2014 at 03:15 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update September 1, 2014)] [Cycle 24 progress (last update September 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update September 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update September 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 September 22. Solar wind speed at SOHO ranged between 372 and 463 km/s.

Solar flux at 20h UTC on 2.8 GHz was 130 (increasing 1.9 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 135.3. The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.4). Three hour interval K indices: 12223222 (planetary), 13323322 (Boulder).

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

At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 236) and 9 active regions using 1K resolution (SN: 143) SDO images on the visible solar disk.

Region 12167 [N06W38] reemerged with penumbra spots.
Region 12168 [S22W19] reemerged with penumbra spots.
Region 12169 [N04W01] decayed slowly and quietly.
Region 12170 [N10E01] decayed slowly and quietly.
Region 12171 [S11E26] decayed and has a fairly simple magnetic layout.
Region 12172 [S11E51] was mostly quiet and stable. The region has minor polarity intermixing and could produce C and M class flares.
Region 12173 [S16E39] decayed slowly and quietly.
New region 12174 [N16W77] emerged on September 17 and was numbered by SWPC 5 days later.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3821 [S10W36] was quiet and stable.
S3835 [N16E33] was quiet and stable.
New region S3836 [S11E08] emerged with penumbra spots.
New region S3837 [N15E15] emerged with a few spots.
New region S3839 [N08E81] rotated into view with a penumbra spot.

C2+ flares (GOES):

Magnitude Peak time (UTC) Location AR Comment
         

Coronal mass ejections (CMEs)

September 20-22: 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 northern hemisphere coronal hole (CH635) was in an Earth facing position on September 20 and early on Sept.21. A recurrent southern hemisphere coronal hole will rotate into an Earth facing positon on September 22-24.

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 conditions with a chance of isolated active intervals on September 23-27 due to coronal hole effects.

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
12165 2014.09.10
2014.09.11
      S08W86           plage
12166 2014.09.12       N11W69          
12167 2014.09.13
2014.09.14
  2   N09W56 0002   AXX   location: N06W38
S3821 2014.09.14   4   S10W36 0010   BXO images/AR_S3821_20140921_2345.png  
12169 2014.09.16
2014.09.17
2 11 5 N05W02 0030 HSX CRO

location: N04W01

12170 2014.09.16
2014.09.17
1 9 5 N11W01 0040 HAX CAO images/AR_12170_20140921_2345.png area: 0080

location: N10E01

12168 2014.09.16
2014.09.17
  3   S22W24 0004   AXX    
12174 2014.09.17
2014.09.22
1 4 3 N15W79 0010 AXX CAO area: 0070

location: N16W77

12171 2014.09.18
2014.09.19
11 19 11 S10E25 0150 EAO EAO

area: 0300

S3831 2014.09.18       S23E10           plage
12173 2014.09.19
2014.09.20
1 4 2 S15E37 0010 HRX CRO location: S16E39
12172 2014.09.20 11 36 19 S11E50 0430 EKC EKC beta-gamma

location: S11E51

area: 0720

S3835 2014.09.21   4 3 N16E33 0010   AXX  
S3836 2014.09.22   2 1 S11E08 0004   BXO    
S3837 2014.09.22   7 4 N15E15 0025   DRO    
S3839 2014.09.22   1   N08E81 0003   AXX    
Total spot count: 27 106 53  
Sunspot number: 87 236 143  (total spot count + 10 * number of spotted regions)
Weighted SN: 55 140 87  (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): 52 83 79 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
2014.09 140.1 (1)   87.3 (2A) / 124.7 (2B) / 84.3 (2C) (65.9 projected, -4.2) (8.8)

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.