Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 9, 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 (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 (July 18, 2015)  

Recent activity

The geomagnetic field was quiet to unsettled on August 8 under the influence of a high speed stream associated with CH680. Solar wind speed at SOHO ranged between 448 and 529 km/s.

Solar flux at 20h UTC on 2.8 GHz was 121.0 (increasing 5.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 117.6. The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 10.1). Three hour interval K indices: 12333223 (planetary), 23333233 (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: 128) and 6 active regions using 1K resolution (SN: 98) SDO images on the visible solar disk.

Region 12393 [N19W72] decayed slowly and quietly.
Region 12394 [N12W50] decayed slowly and was quiet.
Region 12395 [N12W03] decayed and could soon become spotless.
Region 12396 [S17W11] lost the central magnetic deltas and developed a minor delta in a trailing penumbra. Although the region has the potential to produce an M class flare, flare activity has decreased over the last day. Some leading polarity penumbral area was lost while new spots and incresed penumbral area was observed in the trailing polarity.
Region 12398 [N15E48] was quiet and stable.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4671 [N10W53] decayed slowly and quietly.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
           

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

Coronal mass ejections (CMEs)

August 6-8: 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 small coronal hole (CH681) near the equator was in an Earth facing location on August 6 and may be capable of causing a weak disturbance on August 9-10. A recurrent trans equatorial coronal hole (CH682) will likely rotate into an Earth facing position on August 12-13.

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 August 9-10 with a chance of active conditions on August 9-10 due to effects from a small coronal hole (CH681) and quiet on August 11-12.

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
12393 2015.07.27
2015.07.30
1 1 1 N19W72 0010 HRX AXX area: 0005
12394 2015.07.29
2015.07.30
4 4 3 N12W52 0080 CSO CSO

area: 0120

12395 2015.08.02
2015.08.03
1 4 2 N12W01 0000 AXX AXX  
12396 2015.08.03 23 53 29 S17W11 0800 EKC EKC beta-gamma-delta

area: 1080

S4663 2015.08.03       S10W29            
12397 2015.08.03
2015.08.05
1     S12W83 0010 AXX     spotless
S4667 2015.08.04       S18E15            
S4668 2015.08.05       S27W47            
12398 2015.08.06
2015.08.07
2 4 2 N15E47 0020 HAX HRX  
S4670 2015.08.06       N22E08          
S4671 2015.08.06   2 1 N10W53 0005   AXX  
S4672 2015.08.06       S15W57            
S4673 2015.08.06       N05W23            
S4675 2015.08.07       N05W03          
S4676 2015.08.07       N31E02          
S4677 2015.08.07       S18W27          
S4678 2015.08.07       N12W35          
Total spot count: 32 68 38  
Sunspot number: 92 128 98  (total spot count + 10 * number of spotted regions)
Weighted SN: 55 86 56  (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): 101 70 83 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) 8.8
2015.08 (111.1)   19.0 (2A) / 73.6 (2B) / 75.8 (2C) (69.0 projected, -1.2) (8.3)

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.