Solar Terrestrial Activity Report

Activity chart

Last major update issued on September 5, 2014 at 04:05 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 August 9, 2014)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated July 18, 2014]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was quiet to unsettled on September 4. Solar wind speed at SOHO ranged between 354 and 414 km/s.

Solar flux at 20h UTC on 2.8 GHz was 146 (increasing 23 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 133.5. The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.9). Three hour interval K indices: 32221111 (planetary), 22243321 (Boulder).

The background x-ray flux is at the class B9 level.

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 219) and 9 active regions using 1K resolution (SN: 139) SDO images on the visible solar disk.

Region 12152 [S14W38] decayed slowly producing a few C flares.
Region 12153 [S10W65] matured and was mostly quiet.
Region 12154 [S18E09] was quiet and stable.
Region 12155 [S20E61] was quiet and stable.
New region 12156 [N15E57] emerged on September 3 and was numbered the next day by SWPC.
New region 12157 [S12E73] rotated fully into view revealing a large and complex region capable of producing a major flare.
New region 12158 [N15E80] rotated into view with a large penumbra. A major flare is possible.

Spotted regions not numbered (or interpreted differently) by SWPC:
S3776 [N10W12] was quiet and stable.
S3781 [S07E21] reemerged with penumbra spots.
S3786 [S22W11] was quiet and stable.
S3791 [N18E35] reemerged with penumbra spots.
New region S3796 [N08E13] emerged with penumbra spots.

C2+ Flares (GOES):

Magnitude Peak time (UTC) Location AR
C2.4 02:28   12149
C3.1 10:11 S10E78 12157
C2.2 11:22   12152
C6.3 13:30   12152
C5.7 16:32   12157
C3.9 19:31   12157

Coronal mass ejections (CMEs)

September 3-4: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
September 2: A filament eruption, mainly in the northwest quadrant and with extensions into the southwest and northeast quadrant was observed from approximately 16h UTC. A partial halo CME was observed later in LASCO 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 recurrent trans equatorial extension of a northern hemisphere coronal hole (CH634) will rotate into an Earth facing position on September 5.

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 September 5-6 with a chance of active intervals if the CME observed on September 2 reaches Earth. On September 7 quiet conditions are likely.

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
12151 2014.08.22
2014.08.23
2     S08W88 0060 HAX     rotated out of view
12153 2014.08.26
2014.08.29
9 10 5 S09W65 0190 DAI DAO area: 0310
12152 2014.08.26
2014.08.28
16 24 13 S15W38 0310 EKI EAO

beta-gamma

area: 0290

S3772 2014.08.29       S07W50           plage
S3774 2014.08.29       N05W49           plage
S3776 2014.08.30   3 1 N10W12 0008   BXO  
S3779 2014.08.30       N10W32           plage
S3781 2014.08.31   2   S07E21     BXO    
S3782 2014.08.31       N24W28           plage
12154 2014.09.01
2014.09.02
10 21 11 S18E09 0020 CRI DRI area: 0060
S3784 2014.09.01       S28W28           plage
S3786 2014.09.02   1   S23W22 0002   AXX  
S3787 2014.09.02       N45E22           plage
S3788 2014.09.02       S31W09           plage
S3791 2014.09.03   3   N18E35     AXX    
12155 2014.09.03 3 10 4 S20E59 0170 DAO CAO area: 0410
12157 2014.09.03
2014.09.04
12 16 8 S13E68 0200 DAI EKC beta-gamma-delta

area: 0600

location: S12E73

12156 2014.09.03
2014.09.04
2 3 3 N15E56 0010 BXO CRO  
12158 2014.09.04 2 4 3 N16E83 0100 HAX CKO   area: 0380

location: N15E80

S3796 2014.09.04   2 1 N08E13 0008   BXO    
Total spot count: 56 99 49  
Sunspot number: 136 219 139  (total spot count + 10 * number of spotted regions)
Weighted SN: 94 140 90  (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): 62 65 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 (79.8 projected, +1.4) 4.88
2014.04 143.9 144.8 84.7 (79.2 projected, -0.6) 7.88
2014.05 129.7 132.9 75.2 (76.6 projected, -2.6) 5.75
2014.06 122.0 125.8 71.0 (74.0 projected, -2.6) 6.72
2014.07 137.4 141.8 72.5 (71.0 projected, -3.0) 4.50
2014.08 124.6   74.7 (67.5 projected, -3.5) 7.71
2014.09 136.3 (1)   14.6 (2A) / 109.8 (2B) / 71.0 (2C) (63.3 projected, -4.2) (7.6)

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.