Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 22, 2015 at 03:50 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 quiet on August 21 under the decreasing influence of a high speed stream from CH683. Solar wind speed at SOHO ranged between 398 and 481 km/s.

Solar flux at 17h UTC on 2.8 GHz was 111.0 (increasing 17.0 over the last solar rotation, the measurement at 20h was flare enhanced). The 90 day 10.7 flux at 1 AU was 113.5. The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.9). Three hour interval K indices: 11212111 (planetary), 12312321 (Boulder).

The background x-ray flux is at the class B7 level.

At the time of counting spots (see image time), spots were observed in 5 active regions using 2K resolution (SN: 133) and 4 active regions using 1K resolution (SN: 83) SDO images on the visible solar disk.

Region 12401 [S10W56] decayed slowly and quietly.
Region 12403 [S15E23] developed quickly and became more complex with significant polarity intermixing and several magnetic deltas. A major flare is possible.
Region 12404 [N14E14] was quiet and stable.

Spotted regions not numbered (or interpreted differently) by SWPC:
New region S4700 [S16W06] was observed with a penumbra spot.
New region S4701 [S22W32] emerged with a penumbra spot.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
M1.2/1F (LDE) 02:15 S16E39 12403 GOES15  
M1.4/2B 09:48 S17E26 12403 GOES15  
C6.9 19:59 S14E26 12403 SDO/EVE  
M1.1/1N (LDE) 20:34 S12E26 12403 GOES15  
C4.8 21:49 S14E27 12403 SDO/EVE
Holloman @ 21:48
 

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

Coronal mass ejections (CMEs)

August 19-21: 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 (CH684) was in an Earth facing position on August 19-20. Another recurrent trans equatorial coronal hole (CH685) will likely rotate across the central meridian on August 24.

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 active from late on August 22 until August 24 due to effects from CH684.

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
12401 2015.08.12
2015.08.13
2 2 1 S11W58 0010 HRX BXO

reversed polarities

area: 0005

S4687 2015.08.13       S07W50            
S4690 2015.08.14       N09W23            
12402 2015.08.16
2015.08.18
      N05W83            
12403 2015.08.17
2015.08.18
43 72 37 S14E23 0350 DKC EKC beta-gamma-delta

area: 0750

S4697 2015.08.18       S22E34            
12404 2015.08.19
2015.08.20
3 7 4 N14E13 0020 CRO CRO  
S4699 2015.08.20       N19W56          
S4700 2015.08.21   1   S16W06 0001   AXX    
S4701 2015.08.21   1 1 S22W32 0004   AXX    
Total spot count: 48 83 43  
Sunspot number: 78 133 83  (total spot count + 10 * number of spotted regions)
Weighted SN: 64 96 59  (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): 86 73 71 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 (103.0)   42.5 (2A) / 62.7 (2B) / 74.1 (2C) (69.0 projected, -1.2) (12.0)

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.