Solar Terrestrial Activity Report

Activity chart

Last major update issued on September 15, 2015 at 04:35 UT.

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data from 2003.01 (September 1, 2015)
Solar cycle Solar cycles 23-24 (September 1, 2015) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (September 1, 2015) Noon SDO sunspot count 1K Reference: 4K (large file) (*)
  Solar cycles 1-24 (July 17, 2015) POES auroral activity level October 2009 - December 2012
  Comparison of cycles 21, 22, 23 and 24 (September 1, 2015) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12, 13, 14, 16 and 24 (September 1, 2015) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs solar cycles (August 18, 2015)  

Recent activity

The geomagnetic field was quiet to active on September 14 under the influence of effects from CH689. Solar wind speed at SOHO ranged between 371 and 544 km/s. As expected solar wind speed increased when the southernmost extension of CH689 rotated into a geoeffective position.

Solar flux at 20h UTC on 2.8 GHz was 97 (increasing 8.3 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 108.0. The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.5). Three hour interval K indices: 22122433 (planetary), 23333432 (Boulder).

The background x-ray flux is at the class B3 level.

At the time of counting spots (see image time), spots were observed in 6 active regions using 2K resolution (SN: 94) and 5 active regions using 1K resolution (SN: 71) SDO images on the visible solar disk.

Region 12414 [S10W58] decayed further with only 2 spots remaining.
Region 12415 [S20E26] decayed in the trailing spot section. New flux emerged to the southwest of the largest penumbra increasing the magnetic complexity of the region. The region has become more active and will likely produce C flares. There's a minor chance of a small M flare.
Region 12418 [S16E58] was quiet and stable.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4755 [N12E64] developed slowly and quietly.
S4756 [S02W30] was quiet and stable.
New region S4757 [N03E28] emerged with a penumbra spot.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
           

Flare activity (SDO/EVE/ESP XRS-B proxy)

Coronal mass ejections (CMEs)

September 12-14: No obviously Earth directed CMEs were observed in available 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 large northern hemisphere coronal hole (CH689) will be in an Earth facing position on September 9-16. A recurrent trans equatorial coronal hole (CH690) will rotate into an Earth facing position on September 16-17. CH690 appears to be merging with CH689.

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 to unsettled on September 15-18 due to effects from CH689. Quiet to active conditions are possible on September 19-20 as CH690 becomes geoeffective.

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 overlays
Comment
SWPC Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12411 2015.09.03
2015.09.04
      N15W68          
12412 2015.09.05
2015.09.06
      S07W50          
S4743 2015.09.07       N10W48          
S4744 2015.09.07       N07W24            
12417 2015.09.07
2015.09.12
      N25W76            
12414 2015.09.08
2015.09.09
5 2 2 S10W61 0170 ESO ESO

area: 0330

12415 2015.09.10
2015.09.11
16 24 14 S22E28 0150 CAI EAI beta-gamma

area: 0270

location: S20E26

12416 2015.09.10
2015.09.11
      S14W78            
S4752 2015.09.11       S01E10          
12418 2015.09.12
2015.09.13
1 1 1 S15E56 0200 HSX HKX area: 0320
S4755 2015.09.13   5 3 N12E64 0030   CRO  
S4756 2015.09.13   1 1 S02W30 0003   AXX  
S4757 2015.09.14   1   N03E28 0003   AXX    
Total spot count: 22 34 21  
Sunspot number: 52 94 71  (total spot count + 10 * number of spotted regions)
Weighted SN: 37 57 44  (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): 57 52 60 k * (sunspot number)
As of July 1, 2015: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.85 for MSN 1K (MSN=Magnetic Sunspot Number)

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO) (4)
Smoothed sunspot number (4) Average ap
(3)
Measured 1 AU
2014.02 170.3
(cycle peak)
166.3 146.1 (cycle peak) 110.5 (+1.2) 10.70
2014.04 143.9 144.8 112.5 116.4 (+2.1) (solar max) 7.88
2014.05 129.7 132.9 112.5 115.0 (-1.4) 5.75
2014.06 122.0 125.8 102.9 114.1 (-0.9) 6.72
2014.07 137.4 141.8 100.2 112.6 (-1.5) 4.50
2014.08 124.7 127.9 106.9 108.3 (-4.3) 7.71
2014.09 146.6 148.1 130.0 101.9 (-6.4) 9.78
2014.10 153.4 152.9 90.0 97.4 (-4.5) 8.96
2014.11 154.8 151.4 103.6 95.0 (-2.4) 9.33
2014.12 158.7 153.8 112.9 92.6 (-2.4) 11.24
2015.01 141.9 137.3 93.0 89.8 (-2.8) 9.46
2015.02 129.1 126.0 66.7 86.6 (-3.2) 9.92
2015.03 125.9 124.6 54.5 (82.1 projected, -4.5) 16.14
2015.04 128.8 129.7 78.0 (78.0 projected, -4.1) 10.73
2015.05 120.0 122.6 90.0 (75.3 projected, -2.7) 8.29
2015.06 122.3 126.1 68.3 (71.6 projected, -3.7) 13.15
2015.07 107.0 110.8 66.4 (67.9 projected, -3.7) 8.83
2015.08 105.4 108.0 64.6 (66.7 projected, -1.2) 14.58
2015.09 (89.0)   22.8 (2A) / 48.8 (2B) / 66.3 (2C) (67.0 projected, +0.3) (19.9)

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).
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.
4) Updated to new data set from WDC-SILSO on July 1, 2015

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 Universal Time. Comments and suggestions are always welcome.

SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.