Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 30, 2017 at 05:00 UT.

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data since 2003.01 (August 2, 2017)
Solar cycle Solar cycles 23-24 (August 1, 2017) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (August 1, 2017) Noon SDO sunspot count 1K / 4K (*)
  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, 2017) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12, 13, 14, 16 and 24 (August 1, 2017) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (July 16, 2017)  

Recent activity

The geomagnetic field was quiet to active on August 29, a brief disturbance was observed after 18h UT. Solar wind speed at SOHO ranged between 275 and 425 km/s.

Solar flux at 20h UTC on 2.8 GHz was 84.3 (increasing 9.9 over the previous solar rotation). The average 90 day 10.7 flux at 1 AU was 78.7. The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.1). Three hour interval K indices: 11111242 (planetary), 12222343 (Boulder)

The background x-ray flux is at the class B2 level.

At the time of counting spots (see image time), spots were observed in 7 active regions using 2K resolution (SN: 112) and in 4 active regions using 1K resolution (SN: 57) SDO images on the visible solar disk.

Region 12672 [N06W49] gained a few small spots and was quiet.
New region 12673 [S08E64] rotated into view early on August 28 and was numbered by SWPC the next day.
New region 12674 [N13E79] rotated fully into view revealing two large spots. Although the region is currently magnetically not very complex, an M class flare is possible.

Spotted regions not numbered (or interpreted differently) by SWPC:
S5773 [N20W44] reemerged with a tiny spot.
S5777 [N11W13] was quiet and stable.
New region S5780 [N18W57] emerged with a tiny spot.
New region S5781 [S07E05] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
C2.8 03:00   12674 GOES15  

Coronal mass ejections (CMEs)

August 27-29: 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 recurrent northern hemisphere coronal hole (CH822) will likely rotate across the central meridian on August 28-30.

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 poor.

Forecast

The geomagnetic field is expected to be quiet to unsettled on August 30. Quiet to active conditions are likely on August 31 - September 2 due to effects from CH822, minor storm intervals are possible.

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). 4K 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
12672 2017.08.19
2017.08.20
3 17 6 N06W50 0060 CSO CAO  
S5773 2017.08.27   1   N20W44 0002   AXX    
S5774 2017.08.27       N11W29            
S5775 2017.08.28       N43W34         cycle 25 region
12673 2017.08.28
2017.08.29
1 3 2 S08E62 0070 HSX CSO area: 0010
S5777 2017.08.28   2 1 N11W13 0006   AXX  
12674 2017.08.28
2017.08.29
1 17 8 N11E70 0260 DKO EKI area: 0940

location: N13E79

S5780 2017.08.29   1   N18W57 0001   AXX    
S5781 2017.08.29   1   S07E05 0001   AXX  

 

Total spot count: 5 42 17  
Sunspot number: 35 112 57  (total spot count + 10 * number of spotted regions)
Weighted SN: 25 62 37  (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): 39 62 46 k * (sunspot number)
As of May 7, 2016: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.80 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
2016.04 93.3 94.0 38.0 47.8 (-2.7) 9.03
2016.05 93.0 95.3 52.1 44.9 (-2.9) 11.65
2016.06 81.9 84.5 20.9 41.6 (-3.3) 8.44
2016.07 86.0 88.9 32.5 38.6 (-3.0) 9.43
2016.08 85.0 87.1 50.7 36.0 (-2.6) 9.61
2016.09 87.7 88.7 44.7 33.3 (-2.7) 14.54
2016.10 86.1 85.6 33.6 31.4 (-1.9) 15.33
2016.11 78.6 76.9 21.4 29.9 (-1.5) 9.11
2016.12 75.1 72.8 18.9 28.5 (-1.4) 9.34
2017.01 77.3 74.9 25.8 27.9 (-0.6) 9.45
2017.02 76.8 75.0 26.1 (25.9 projected, -2.0) 9.58
2017.03 74.6 73.9 17.7 (23.1 projected, -2.8) 14.20
2017.04 80.3 80.8 32.6 (21.1 projected, -2.0) 11.70
2017.05 73.6 75.2 18.8 (20.0 projected, -1.1) 8.09
2017.06 74.7 77.1 19.4 (19.0 projected, -1.0) 6.08
2017.07 77.4 79.9 18.3 (17.9 projected, -1.1) 8.97
2017.08 (77.1)   22.2 (2A) / 23.8 (2B) / 27.2 (2C) (16.4 projected, -1.5) (9.7)

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.