Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 24, 2018 at 06:05 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 (June 9, 2018)
Solar cycle Solar cycles 23-24 (June 1, 2018) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (June 1, 2018) / Cycle 25 spots (June 1, 2018) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (July 17, 2015) POES auroral activity level October 2009 - December 2012]
  Comparison of cycles 21, 22, 23 and 24 (June 1, 2018) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12, 13, 14, 16 and 24 (June 1, 2018) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (May 10, 2018)  

Recent activity

The geomagnetic field was quiet to active on June 23 under the influence of effects from CH870. Solar wind speed at SOHO ranged between 299 and 474 km/s.

Solar flux at 20h UTC on 2.8 GHz was 77.1 (increasing 4.2 over the previous solar rotation). The average 90 day 10.7 flux at 1 AU was 72.2. The Potsdam WDC planetary A index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 15.0). Three hour interval K indices: 23244334 (planetary), 24233324 (Boulder)

The background x-ray flux is at the class B1 level.

At the time of counting spots (see image time), spots were observed in 2 active regions using 2K resolution (SN: 37) and in 2 active regions using 1K resolution (SN: 30) SDO images on the visible solar disk.

Region 12713 [N04W80] decayed slowly and was mostly quiet.
Region 12715 [N08W20] lost area, however, opposite polarity umbrae within the largest penumbra are now closer and a weak magnetic delta has formed. There is a small chance of a minor M class flare.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
           

Coronal mass ejections (CMEs)

June 21-23: 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 extension (CH870) of the northern polar coronal hole was in an Earth facing position on June 19-21. A recurrent trans equatorial coronal hole (CH871) will likely rotate across the central meridian on June 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.

Forecast

The geomagnetic field is expected to be quiet to unsettled on June 24 due to effects from CH870. Quiet conditions are likely on June 25-26.

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
12713 2018.06.11
2018.06.12
6 5 3 N05W79 0070 DAO DAO

location: N04W80

area: 0050

12715 2018.06.18
2018.06.19
8 12 7 N08W21 0120 DAC DAC beta-delta
S5990 2018.06.21       N15E23            
S5991 2018.06.21       S03W09            
S5992 2018.06.21       S55E09          

 

Total spot count: 14 17 10  
Sunspot number: 34 37 30  (total spot count + 10 * number of spotted regions)
Weighted SN: 24 27 20  (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): 37 20 24 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)
Smoothed sunspot number (4) Average ap
(3)
Measured 1 AU
2014.02 170.3
(cycle peak)
166.3 146.1 (cycle peak) 110.5 10.70
2014.04 143.9 144.8 112.5 116.4 (solar max) 7.88
2016.11 78.6 76.9 21.4 29.9 (-1.6) 9.11
2016.12 75.1 72.8 18.9 28.5 (-1.4) 9.34
2017.01 77.3 74.9 25.8 27.8 (-0.7) 9.45
2017.02 76.8 75.0 26.1 26.5 (-1.3) 9.58
2017.03 74.6 73.9 17.7 25.7 (-0.8) 14.20
2017.04 80.3 80.8 32.6 24.8 (-0.9) 11.70
2017.05 73.6 75.2 18.8 23.3 (-1.5) 8.09
2017.06 74.7 77.1 19.4 22.2 (-1.1) 6.08
2017.07 77.4 79.9 18.3 21.0 (-1.2) 8.97
2017.08 77.9 79.8 33.1 19.5 (-1.5) 10.66
2017.09 91.3 92.3 43.6 18.2 (-1.3) 18.22 (cycle peak)
2017.10 76.4 75.6 13.2 16.6 (-1.6) 10.30
2017.11 72.2 70.6 5.7 15.4 (-1.2) 10.06
2017.12 71.6 69.3 8.2 (14.7 projected, -0.7) 7.33
2018.01 69.9 67.7 6.7 (13.7 projected, -1.0) 5.53
2018.02 72.0 70.2 10.6 (11.9 projected, -1.8) 6.40
2018.03 68.3 67.6 2.5 (9.0 projected, -2.9) 7.91
2018.04 70.0 70.5 8.9 (7.1 projected, -1.9) 6.80
2018.05 70.8 72.4 13.2 (6.7 projected, -0.4) 7.16
2018.06 (73.0)   13.5 (2A) / 17.6 (2B) / 15.7 (2C) (6.4 projected, -0.3) (5.6)

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.

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.