Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 26, 2024 at 07:20 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, 2024)
Solar cycle Solar cycles 23-25 (June 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (June 1, 2024) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (July 1, 2020) POES auroral activity level [October 2009 - December 2012]
  Comparison of cycles 21-25 (June 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (June 1, 2024) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (June 17, 2024) Cycle 25 spots (final update December 25, 2019)
  Solar cycles 24-25 transition using 365d smoothing Research: Solar Cycle 25 Started on November 17, 2019 with 365 Days Smoothing
Calculating the Strength of Solar Cycle 25 Using 365-day Smoothing

Recent activity

The geomagnetic field was at quiet levels on June 25. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux returned to background levels.

Solar flux density measured at 20h UT on 2.8 GHz was 193.7 - increasing 23.2 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 162.90. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 162.90 on December 26, 2023). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.4). Three hour interval K indices: 11222221 (planetary), 21432432 (Boulder), 12222422 (Andenes).

The background x-ray flux is at the class C2 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 338) and in 13 active regions using 1K resolution (SN: 213) SDO/HMI images.

Region 13719 [S16W15] decayed early in the day, then gained a few spots late in the day.
Region 13720 [S06E00] displayed no major changes and could produce M flares.
Region 13721 [N25E25] was mostly quiet and stable.
Region 13722 [S12E23] was quiet and stable.
Region 13723 [S19E45] decayed slowly. The region has a magnetic delta configuration in the intermediate spot section. The leading spot section has both polarities and could be split off into a separate region.
Region 13725 [N19E10] was quiet and stable.
Region 13726 [S05E41] was quiet and stable.
New region 13727 [S18E61] rotated into view on June 24 and was numbered the next day by SWPC.
New region 13728 [S27E58] rotated into view on June 23 and received its NOAA number 2 days later.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9815 [N16W05] decayed slowly and quietly.
S9824 [N25W24] reemerged with tiny spots.
S9828 [S19W59] developed slowly and quietly.
S9830 [S05E61] was quiet and stable.
New region S9831 [S03E82] rotated into view with several spots. M flares are possible.
New region S9832 [N06E19] was observed with tiny spots in an old plage area.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
          Data gaps before 12:00 UT
C3.1 02:08 southeast limb S9831 GOES16  
C2.7 04:10   13723 GOES16  
M1.0 12:44 S18E58 13723 GOES16  
C3.8 14:43 southwest limb S9829 GOES16  
C5.0 14:55 southeast limb S9831 GOES16  
C3.2 15:17 southeast limb S9831 GOES16  
C3.7 15:49   13723 GOES16  
C4.0 16:04 southwest limb S9829 GOES16  
C3.9 17:50   13720 GOES16  
C3.2 18:50   S9831 GOES16  
C5.6 19:25 S19E46 13723 GOES16  
C3.3 20:13 S19E48 13723 GOES16  
C3.3 20:26   13719 GOES16  
C3.7 22:04   13727 GOES16  
C3.9 22:31   13720 GOES16  
C3.0 23:55 southwest limb S9829 GOES16  

Coronal mass ejections (CMEs)

June 23-25: No obviously Earth directed CMEs observed. A large filament eruption in the southwestern quadrant late on June 24 was associated with a CME. If there are any Earth directed components a weak disturbance will be possible on June 28.

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 positive polarity southern hemisphere coronal hole will be Earth facing on June 25-26.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to active on June 26 and quiet to unsettled on June 27-28.

Coronal holes (1) Coronal mass ejections (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 officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. 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. SWPC data considered to be not sufficiently precise (location, area, classification) are colored red.

Active region SWPC date numbered
STAR detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlays
Comment
SWPC/
USAF
Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
S9805 2024.06.16       S11W50            
13718 2024.06.18
2024.06.19
      N12W69           location: N17W62
13719 2024.06.19
2024.06.19
13 20 11 S14W12 0150 DSO DHO

area: 0370

location: S16W15

13720 2024.06.19
2024.06.19
15 40 23 S06W03 0130 DAI DAI

area: 0190

location: S06E00

S9815 2024.06.19   7 1 N16W05 0012   BXO  
S9816 2024.06.20       S17W56            
13725 2024.06.20
2024.06.23
  13 1 N18E13 0020   AXX location: N19E10
13721 2024.06.21
2024.06.21
2 12 3 N25E24 0100 HAX CAO area: 0160
13722 2024.06.21
2024.06.21
1 18 8 S12E22 0050 HSX CSO area: 0280

location: S12E23

S9820 2024.06.21       N04W46            
13723 2024.06.22
2024.06.23
12 34 17 S19E44 0210 FAI FAC beta-gamma-delta

area: 0270

location: S19E45

13726 2024.06.22
2024.06.23
  6 1 S04E35 0010   BXO location: S05E41
13724 2024.06.23 1     S14E22 0050 HSX       SWPC split this off from AR 13722
S9824 2024.06.23   2   N26W34 0003   AXX    
13728 2024.06.23
2024.06.25
4 5 4 S25E55 0010 BXO CRO area: 0020

location: S27E58

S9826 2024.06.23       N08W34            
13727 2024.06.24
2024.06.25
1 13 7 S18E59 0080 HSX CHO area: 0310

location: S18E61

S9828 2024.06.24   5 2 S19W59 0015   CRO  
S9830 2024.06.24   4 1 S05E61 0007   BXO  
S9831 2024.06.25   6 4 S03E82 0270   DAO    
S9832 2024.06.25   3   N06E19 0008   BXO    
Total spot count: 49 188 83  
Sunspot number: 129 338 213  (total spot count + 10 * number of spotted regions)
Weighted SN: 84 239 134  (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): 142 186 170  

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 (SC24 peak) 110.5 10.70
2014.04 143.9 144.8 112.5 116.4 (SC24 solar max) 7.88
2017.09 91.3 92.3 43.6 18.2 (-1.3) 18.22
(SC24 peak)
2019.11 70.2 68.7 0.5 2.0 (-0.6)
(Solar minimum using 365d smoothing:
November 17, 2019)
4.19
2019.12 70.8 68.6 1.6 1.8 (-0.2)
(ISN 13 months smoothed
solar minimum)
3.22
2022.10 133.5 132.7 95.5 98.9 (+2.4) 11.16
2022.11 123.4 120.7 80.5 101.2 (+2.3) 9.33
2022.12 147.9 143.4 112.8 106.7 (+5.5) 10.99
2023.01 182.4 176.6 144.4 113.3 (+6.6) 8.73
2023.02 167.2 163.2 111.3 117.8 (+3.5) 14.48
2023.03 157.2 155.6 123.3 121.1 (+3.3) 14.42
2023.04 145.4 146.4 97.6 122.9 (+1.8) 13.40
2023.05 155.6 159.2 137.4 124.2 (+1.3) 10.67
2023.06 161.7 166.8 160.5 125.3 (+1.1) 8.95
2023.07  176.4 182.2 160.0 124.4 (-0.9) 8.15
2023.08  153.7 157.6 114.8 124.1 (-0.3) 7.19
2023.09  154.4 156.0 134.2 123.9 (-0.2) 14.26
2023.10  142.8 141.9 99.4 124.8 (+0.9) 8.16
2023.11 153.5 150.2 105.4 127.8 (+3.0) 12.20
2023.12 151.1 146.4 114.2 (128.7 projected, +0.9) 9.60
2024.01 164.6 159.3 123.0 (127.0 projected, -1.7) 5.46
2024.02 172.5 168.3 124.7 (126.2 projected, -0.8) 5.31
2024.03 154.4 152.9 104.9 (125.6 projected, -0.6) 11.03
2024.04 161.3 162.6 136.5 (125.6 projected, -0.0) 9.69
2024.05 187.7
(cycle peak)
191.9 171.7 (SC25 peak) (126.7 projected, +1.1) 23.56
(current
SC25 peak)
2024.06 185.0 (1)   128.4 (2A) / 154.1 (2B) / 156.8 (2C) (125.9 projected, -0.8) (8.1)
2024.07       (124.2 projected, -1.7)  
2024.08       (122.2 projected, -2.0)  
2024.09       (121.0 projected, -1.2)  
2024.10       (119.6 projected, -1.4)  
2024.11       (114.5 projected, -5.1)  
2024.12       (109.1 projected, -5.4)  

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz and any corrections applied to that measurement.
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) Source: WDC-SILSO, Royal Observatory Of Belgium, Brussels

Solar cycles 24-25

Smoothed SF and sunspot numbers

Update on the progress of solar cycle 25 as of June 6, 2024

May 2024 easily became the month with the highest sunspot counts during solar cycle 25, and early June has seen no change in that pattern of many spot groups, some of which are large and complex. The next candidate for solar max is still uncertain, however, May 20-21, 2024 has all of the smoothed 365d sunspot numbers as well as the 365d smoothed solar flux signalling a peak on those days.

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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.