Solar Terrestrial Activity Report

Activity chart

Last major update issued on September 19, 2014 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 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 18. Solar wind speed at SOHO ranged between 320 and 376 km/s. A disturbance began after 17h UTC and is causing active conditions early on September 19.

Solar flux at 20h UTC on 2.8 GHz was 120 (decreasing 6.4 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 134.1. The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.1). Three hour interval K indices: 21101123 (planetary), 21112223 (Boulder).

The background x-ray flux is at the class B6 level.

At the time of counting spots (see image time), spots were observed in 9 active regions using 2K resolution (SN: 158) and 7 active regions using 1K resolution (SN: 101) SDO images on the visible solar disk.

Region 12164 [S14W64] decayed slowly, a weak magnetic delta structure is still present in the largest penumbra.
Region 12166 [N12W10] decayed slowly and was quiet.
Region 12167 [N07E07] reemerged with penumbra spots.
Region 12168 [S22E32] was mostly quiet and stable.
Region 12169 [N04E54] was the most active region on the visible disk producing C flares and a minor M class flare. Magnetically the region has a simple structure.
Region 12170 [N10E54] was quiet and stable.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3821 [S12E04] was quiet and stable.
New region S3830 [S10E80] rotated into view and could produce C flares.
New region S3831 [S23E62] emerged with one spot.

C2+ flares (GOES):

Magnitude Peak time (UTC) Location AR Comment
C6.4 07:09 N05E70 12169  
M1.2 08:41 N08E70 12169  
C3.4 17:30   12169  

Coronal mass ejections (CMEs)

September 16-18: 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]

An extension of a large southern hemisphere coronal hole was in an Earth facing position on September 15.

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 active on September 19 and quiet on September 20-21.

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
12163 2014.09.06
2014.09.07
      S15W86           plage
12164 2014.09.09
2014.09.11
8 12 5 S13W66 0030 CAO DAC beta-delta

location: S14W64

12165 2014.09.10
2014.09.11
      S08W30          
S3816 2014.09.11       S08W54           plage
S3817 2014.09.11       N09W54           plage
12166 2014.09.12 9 19 10 N13W14 0030 CAO BXO  
12167 2014.09.13
2014.09.14
  12 3 N08W03 0020   BXO   location: N07E07
S3821 2014.09.14   2   S12E04 0006   BXO  
S3822 2014.09.14       N16W41           plage
S3823 2014.09.15       S07E16           plage
S3824 2014.09.15       S09W43         plage
12169 2014.09.16
2014.09.17
2 5 3 N05E53 0050 CAO CSO area: 0100
12170 2014.09.16
2014.09.17
1 2 1 N10E51 0040 HAX HSX area: 0120

location: N10E54

12168 2014.09.16
2014.09.17
5 13 7 S21E30 0020 CAO CRO area: 0040
S3829 2014.09.17       N15W24         plage
S3830 2014.09.18   2 2 S10E80 0220   DSO    
S3831 2014.09.18   1   S23E62 0002   AXX    
Total spot count: 25 68 31  
Sunspot number: 75 158 101  (total spot count + 10 * number of spotted regions)
Weighted SN: 50 91 54  (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): 45 55 56 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
2014.09 143.2 (1)   79.4 (2A) / 132.3 (2B) / 84.9 (2C) (65.9 projected, -4.2) (8.1)

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.