Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 28, 2015 at 04:05 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 major storm on August 27. Solar wind speed at SOHO ranged between 304 and 404 km/s. The disturbance (source unknown) caused by a low speed, high density and cold stream and which began on August 26 and which is still strong early on August 28, continued to be associated with a moderately strong interplanetary magnetic field with a southward Bz.

Solar flux at 20h UTC on 2.8 GHz was 110.2 (increasing 9.5 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 115.0. The Potsdam WDC planetary A index was 48 (STAR Ap - based on the mean of three hour interval ap indices: 48.0). Three hour interval K indices: 56543546 (planetary), 47544424 (Boulder).

The background x-ray flux is at the class B4 level.

At the time of counting spots (see image time), spots were observed in 6 active regions using 2K resolution (SN: 121) and 4 active regions using 1K resolution (SN: 75) SDO images on the visible solar disk.

Region 12403 [S15W57] lost spots and penumbral area. As there is still one magnetic delta in the leading spot section, another M class flare is possible.
New region 12405 [S21E49] was first observed with spots on August 26 and was numbered by SWPC the next day as the region developed slowly.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4703 [N16W08] was quiet and stable.
New region S4714 [S03E18] was observed with a penumbra spot.
New region S4715 [N11E27] was observed with penumbra spots.
New region S4716 [S08W69] emerged with a penumbra spot to the northwest of AR 12403.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C2.5 05:02   12403 GOES15 C1.9 @ SDO/EVE
M2.9/1N (LDE) 05:44 S14W45 12403 GOES15  
C3.2 07:30   12403 SDO/EVE  

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

Coronal mass ejections (CMEs)

August 25-27: No obviously Earth directed CMEs were observed.

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. Another recurrent trans equatorial coronal hole (CH686) will likely rotate across the central meridian on August 30.

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 28 and quiet to active on August 29 becoming quiet to unsettled on August 30-31

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
25 41 24 S15W57 0890 FKC FKC beta-gamma-delta
12404 2015.08.19
2015.08.20
      N14W74          
S4703 2015.08.22   10 6 N16W08 0025   BXO images/AR_S4703_20150827_2345.png images/AR_S4703_20150826_2345.png  
S4704 2015.08.22       S23W43            
S4706 2015.08.23       S15W22            
S4709 2015.08.24       N22W56            
S4710 2015.08.25       N05W58            
S4711 2015.08.25       S02W41            
S4712 2015.08.25       S13W33          
12405 2015.08.26
2015.08.27
1 5 4 S21E45 0010 AXX BXO area: 0020

location: S21E49

S4714 2015.08.27   1   S03E18 0002   AXX    
S4715 2015.08.27   3 1 N11E27 0007   AXX    
S4716 2015.08.27   1   S08W69 0002   AXX    
Total spot count: 26 61 35  
Sunspot number: 46 121 75  (total spot count + 10 * number of spotted regions)
Weighted SN: 36 71 45  (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): 51 67 64 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 (106.5)   55.0 (2A) / 63.1 (2B) / 77.3 (2C) (69.0 projected, -1.2) (13.7)

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.