Solar Terrestrial Activity Report

Activity chart

Last major update issued on September 22, 2014 at 04:30 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 21. Solar wind speed at SOHO ranged between 421 and 553 km/s under the influence of a high speed coronal hole stream.

Solar flux at 20h UTC on 2.8 GHz was 124 (decreasing 13.3 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 134.9. The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.6). Three hour interval K indices: 13111111 (planetary), 23122221 (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 9 active regions using 2K resolution (SN: 177) and 9 active regions using 1K resolution (SN: 136) SDO images on the visible solar disk.

Region 12166 [N14W44] decayed slowly and produced the largest flare of the day.
Region 12169 [N05E12] was quiet and stable.
Region 12170 [N10E14] was quiet and stable.
Region 12171 [S10E40] developed slowly and could produce C and minor M class flares.
Region 12172 [S11E65] is a compact region with M class flare potential. The region was mostly quiet during the day.
Region 12173 [S15E53] was quiet and stable.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3821 [S14W32] was quiet and stable.
S3829 [N15W64] developed slowly and quietly.
New region S3835 [N15E46] emerged with penumbra spots.

C2+ flares (GOES):

Magnitude Peak time (UTC) Location AR Comment
C2.0 07:14   12172  
C5.2/1F (LDE) 11:53 N11W40 12166  

Coronal mass ejections (CMEs)

September 19-21: 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 likely 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.

Forecast

The geomagnetic field is expected to be quiet on September 22. On September 23-27 coronal hole effects could cause quiet to unsettled conditions with a chance of isolated active intervals.

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
      S08W72           plage
12166 2014.09.12   4 3 N11W55 0010   BXO location: N14W44
12167 2014.09.13
2014.09.14
      N09W42         location: N07W31
S3821 2014.09.14   2 1 S14W32 0005   BXO images/AR_S3821_20140921_2345.png  
12169 2014.09.16
2014.09.17
2 7 6 N05E14 0040 CAO CAO

area: 0070

12170 2014.09.16
2014.09.17
1 15 7 N11E13 0050 HAX CSO images/AR_12170_20140921_2345.png area: 0100

location: N10E14

12168 2014.09.16
2014.09.17
      S22W10         plage
S3829 2014.09.17   4 1 N15W64 0013   BXO  
12171 2014.09.18
2014.09.19
8 21 13 S10E39 0160 EAI EAI

beta-gamma

area: 0330

S3831 2014.09.18       S23E23           plage
12173 2014.09.19
2014.09.20
1 6 1 S15E51 0020 HRX CRO location: S15E53
S3833 2014.09.19       N07W58           plage
12172 2014.09.20 10 24 12 S11E63 0320 EKC EKC beta-gamma

location: S11E65

area: 0650

S3835 2014.09.21   4 2 N14E46 0010   BXO    
Total spot count: 22 87 46  
Sunspot number: 72 177 136  (total spot count + 10 * number of spotted regions)
Weighted SN: 50 115 74  (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): 43 62 75 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.