Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 27, 2015 at 04:30 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 (August 1, 2015)
Solar cycle Solar cycles 23-24 (August 1, 2015) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (August 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 (August 1, 2015) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12, 13, 14, 16 and 24 (August 1, 2015) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs solar cycles (August 18, 2015)  

Recent activity

The geomagnetic field was unsettled to active on August 26. Solar wind speed at SOHO ranged between 350 and 424 km/s. A disturbance (source unknown) was observed beginning at SOHO near 08:15 UT. For the remainder of the day the solar wind was low speed, high density and fairly cold while the interplanetary magnetic field slowly became stronger with an increasingly more southward Bz. Early on August 27 minor to major geomagnetic storming is being observed.

Solar flux at 23h UTC on 2.8 GHz was 118.7 (increasing 16.7 over the last solar rotation, the measurements at 17 and 20h UT were flare enhanced). The 90 day 10.7 flux at 1 AU was 114.9. The Potsdam WDC planetary A index was 25 (STAR Ap - based on the mean of three hour interval ap indices: 25.1). Three hour interval K indices: 33344444 (planetary), 33355333 (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 5 active regions using 2K resolution (SN: 121) and 3 active regions using 1K resolution (SN: 67) SDO images on the visible solar disk.

Region 12403 [S15W43] decayed slowly in the trailing spot section with penumbral fragmentation observed and the loss of a magnetic delta. The leading spot section has two magnetic deltas and there is a fair chance of an M class event before the region rotates out of view. losing penumbral area and spots.
Region 12404 [N14W58] decayed slowly and quietly.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4703 [N16E22] gained more trailing polarity penumbra spots and was quiet.
S4712 [S13W20] was quiet and stable.
New region S4713 [S21E62] was observed with penumbra spots.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C9.5/2N (LDE) 13:53 S11W41 12403 GOES15  
C5.0 15:07   12403 GOES15  
C2.6 19:11   12403 SDO/EVE triggered extensive filament eruption to the north of AR 12403
C2.8 19:43     SDO/EVE  
C2.3 00:08 (Aug.27, began at 23:51)     GOES15 source probably 12403, simultaneous activity in AR S4713

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

Coronal mass ejections (CMEs)

August 24-25: No obviously Earth directed CMEs were observed.
August 26: A CME was observed off the west limb from 20:36 UT in LASCO C2 imagery. This was likely associated with an extensive filament eruption to the north and northeast of AR 12403. Further LASCO imagery will be required to determine if the CME has any Earth directed components.

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 coronal hole (CH685) was in an Earth facing position on August 25-26.

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 fair to good.

Forecast

The geomagnetic field is expected to be unsettled to major storm on August 27. A high speed stream associated with CH685 could become geoeffective late on August 27 and may cause quiet to active conditions on August 28-29.

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
12403 2015.08.17
2015.08.18
35 53 31 S16W44 1100 FKC FKC beta-gamma-delta

area: 0850

12404 2015.08.19
2015.08.20
  1   N14W60 0001   AXX  
S4703 2015.08.22   14 5 N16E22 0030   BXO images/AR_S4703_20150826_2345.png  
S4704 2015.08.22       S23W30            
S4706 2015.08.23       S15W09            
S4707 2015.08.23       S12W55            
S4709 2015.08.24       N22W43            
S4710 2015.08.25       N05W45          
S4711 2015.08.25       S02W28          
S4712 2015.08.25   1   S13W20 0001   AXX  
S4713 2015.08.26   2 1 S21E62 0006   AXX    
Total spot count: 35 71 37  
Sunspot number: 45 121 67  (total spot count + 10 * number of spotted regions)
Weighted SN: 45 81 47  (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): 50 67 57 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
2014.03 149.9 148.5 128.7 114.3 (+3.8) 4.88
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 (86.8 projected, -3.0) 9.92
2015.03 125.9 124.6 54.5 (83.1 projected, -3.7) 16.14
2015.04 128.8 129.7 78.0 (79.8 projected, -3.3) 10.73
2015.05 120.0 122.6 90.0 (77.4 projected, -2.4) 8.29
2015.06 122.3 126.1 68.3 (73.9 projected, -3.5) 13.15
2015.07 107.0 110.8 66.4 (70.2 projected, -3.7) 8.83
2015.08 (106.3)   53.5 (2A) / 63.8 (2B) / 78.2 (2C) (69.0 projected, -1.2) (12.4)

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.