Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 11, 2024 at 03:35 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 (March 3, 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 to active levels on June 10. A solar wind shock was observed at 16:34 UT at ACE, the arrival of the June 8 CME. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux was at 1.3 pfu at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 177.8 - decreasing 42.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 161.92. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 161.92 on December 11, 2023). The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.0). Three hour interval K indices: 21111342 (planetary), 20122332 (Boulder), 30112342 (Andenes).

The background x-ray flux is at the class C3 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 243) and in 10 active regions using 1K resolution (SN: 144) SDO/HMI images.

Region 13702 [N17W35] decayed slowly and quietly.
Region 13703 [S07W73] decayed further and was quiet.
Region 13704 [S17W31] decayed slowly and quietly.
Region 13707 [S14E06] decayed slowly and was mostly quiet.
Region 13708 [S22E20] was quiet and stable.
Region 13709 [S09E27] was mostly unchanged and could produce M class flares.
Region 13710 [S16W65] decayed slowly and quietly.
Region 13711 [S09E39] decayed slowly and quietly.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9778 [N16W12] was quiet and stable
S9781 [S24E07] was quiet and stable.
S9785 [N17E52] was quiet and stable.
S9789 [N22E05] was quiet and stable.
New region S9790 [N22W58] emerged before noon with tiny spots.
New region S9791 [S24E33] emerged with tiny spots.

An active region behind the southeast limb produced several C flares and may be capable of M class flaring.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.6 00:22   13697 GOES16  
C4.4 03:53   13697 GOES16  
C5.9 04:32 behind southeast limb   GOES16  
M3.3 06:09   13697 GOES16  
C2.7 08:31   13697 GOES16  
C2.8 08:57   13697 GOES16  
C2.5 09:09   13697 GOES16  
M1.6 09:54 behind southwest limb 13697 GOES16  
M2.2 10:06 behind southwest limb 13697 GOES16  
M5.3 10:57 behind southwest limb 13697 GOES16  
X1.5 11:08 S19W90+, behind southwest limb 13697 GOES16  
M1.3 13:29 behind southwest limb 13697 GOES16  
C7.4 14:34 behind southwest limb 13697 GOES16  
C5.6 15:18 behind southwest limb 13697 GOES16  
C6.0 15:29 behind southeast limb   GOES16  
C4.9 16:25 behind southwest limb 13697 GOES16  
C5.7 17:37 behind southwest limb 13697 GOES16  
M9.5 18:40 behind southwest limb 13697 GOES16 weak type II radio sweep
C5.3 21:38 behind southwest limb 13697 GOES16  
C7.4 21:58 behind southwest limb 13697 GOES16  
C5.1 23:41 behind southeast limb   GOES16  

Coronal mass ejections (CMEs)

June 9-10: No obviously Earth directed CME observed.
June 8: A partial halo CME was observed after the M9 flare in AR 13697 at 01:49 UT. The CME reached Earth on June 10.

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 southern hemisphere negative polarity coronal hole (CH1225) would have been Earth facing on June 10. CH1225 seems to have closed before rotating across the central meridian.

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. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be at quiet to minor storm levels on June 11 due to CME effects and quiet to unsettled on June 12-13.

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
13697 2024.05.27
2024.05.28
13     S19W99 0250 EKC     rotated out of view

SWPC reports the same number of spots as on the previous day. This is questionable at best

13703 2024.05.31
2024.06.03
2 9 2 S07W74 0070 DAO CRO

location: S07W73

area: 0040

13702 2024.06.01
2024.06.02
3 8 2 N17W35 0080 CSO CSO

area: 0130

S9762 2024.06.01       S14W45            
13704 2024.06.02
2024.06.03
1 1   S18W32 0010 AXX AXX

location: S17W31

area: 0002

13706 2024.06.03
2024.06.04
      S12W55           location: S12W60
S9769 2024.06.03       N09W24          
S9771 2024.06.04       N36W35            
S9772 2024.06.04       S05W38            
S9774 2024.06.05       S27W13            
13707 2024.06.05
2024.06.06
5 13 6 S15E03 0040 CSO DAO

location: S14E06

13708 2024.06.05
2024.06.06
2 5 3 S22E18 0060 HSX CSO area: 0100

location: S22E20

13710 2024.06.06
2024.06.09
4 6 3 S16W64 0020 CSO CRO location: S16W65
S9778 2024.06.06   3 2 N16W12 0006   AXX  
13709 2024.06.06
2024.06.07
23 31 18 S08E28 0250 DKI DKI area: 0420

location: S09E27

S9781 2024.06.07   8   S23E08 0012   BXO  
S9782 2024.06.07       S09E19          
13711 2024.06.07
2024.06.09
3 9 5 S08E39 0060 DAO DRO location: S09E39
S9784 2024.06.08       S09W40            
S9785 2024.06.08   1   N17E52 0002   AXX  
S9786 2024.06.08       S23W11          
S9787 2024.06.09       S23W35          
S9789 2024.06.09   3   N13E13 0008   BXO  
S9790 2024.06.10   4 2 N22W58 0015   CRO    
S9791 2024.06.10   2 1 S24E33 0006   BXO    
Total spot count: 56 103 44  
Sunspot number: 146 243 144  (total spot count + 10 * number of spotted regions)
Weighted SN: 106 140 81  (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): 161 134 115  

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)
2024.06 186.7 (1)   58.0 (2A) / 174.1 (2B) / 176.9 (2C) (125.9 projected, -0.8) (9.0)
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.