Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 25, 2024 at 03:25 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 24. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux became slightly elevated after 16h UT.

Solar flux density measured at 20h UT on 2.8 GHz was 198.7 - increasing 32.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 162.80. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 162.80 on December 25, 2023). The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4). Three hour interval K indices: 20000112 (planetary), 31122422 (Boulder), 41001103 (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 13 active regions using 2K resolution (SN: 268) and in 9 active regions using 1K resolution (SN: 156) SDO/HMI images.

Region 13719 [S15W02] was mostly quiet and stable.
Region 13720 [S06E13] developed slowly producing several flares.
Region 13721 [N25E38] was quiet and stable.
Region 13722 [S12E37] was mostly quiet and stable.
Region 13723 [S19E58] is the most complex region on the visible disk and could produce a major flare.
Region 13725 [N21E23] decayed slowly and quietly.
Region 13726 [S04E51] decayed slowly and quietly.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9815 [N17E11] developed as new flux emerged.
S9825 [S27E70] was quiet and stable.
New region S9827 [S18E74] rotated into view with a large, mature spot.
New region S9828 [S19W41] emerged before noon, then decayed slowly.
New region S9829 [S10W74] emerged with a tiny spot.
New region S9830 [S04E76] rotated into view with tiny spots.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C4.0 00:02   13716 GOES16  
C7.2 01:02 southwest limb 13712 GOES16  
C7.2 01:05   13720 GOES16  
C6.3 01:29 southwest limb 13712 GOES16  
C6.3 01:40   13720 GOES16  
M1.3 04:17 southwest limb 13712 GOES16 simultaneous flare in AR 13720
M1.8 04:52 southwest limb 13712 GOES16  
M1.2 07:01 southwest limb 13713 GOES16  
M1.0 07:46 southwest limb 13712 GOES16  
M1.0 07:56 southwest limb 13712 GOES16  
C9.5 08:28 southwest limb 13713 GOES16 simultaneous flare in AR S9825
C9.5 09:52 southwest limb 13713 GOES16  
C9.5 10:24 southwest limb 13713 GOES16  
C9.6 11:02 northwest limb 13716 GOES16 simultaneous flare in AR 13723
M1.1/1F 11:13   13720 GOES16  
M1.5 11:48 southwest limb 13713 GOES16  
C9.3 12:04 southwest limb 13713 GOES16  
C8.6 13:24 southwest limb 13712 GOES16 incorrectly attributed to AR 13713 by SWPC
C6.8 13:36 southwest limb 13713 GOES16  
C6.0 13:45   13723 GOES16  
C7.5/1N 13:57   13720 GOES16  
C5.6 14:15 southwest limb 13712 GOES16 simultaneous flare in AR S9825
C7.9 15:12   13723 GOES16  
C7.4 15:41   13723 GOES16  
C8.3 16:10   13723 GOES16  
C6.9 16:45 behind southeast limb   GOES16 simultaneous flares in ARs 13720 and 13713
C7.8 17:13   13723 GOES16  
C4.4 18:41 southwest limb 13713 GOES16  
M1.1 19:10 southwest limb 13713 GOES16 incorrectly attributed to AR 13712 by SWPC
C5.8 19:26 northwest limb 13716 GOES16  
C5.4 19:49 northwest limb 13716 GOES16  
C4.1 20:54   13719 GOES16 simultaneous flare in AR 13720
          Data gap after 21:25 UT

Coronal mass ejections (CMEs)

June 22-24: No obviously Earth directed CMEs 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]

No obvious coronal holes are currently in or near Earth facing locations.

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 on June 25-27.

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
13713 2024.06.11
2024.06.12
6     S14W88 0360 EKC     rotated out of view
13716 2024.06.12 4     N09W95 0200 EAO     rotated out of view
S9805 2024.06.16       S11W37            
13718 2024.06.18
2024.06.19
      N12W55           location: N17W49
S9812 2024.06.18       N27W55            
13719 2024.06.19
2024.06.19
14 22 16 S14E02 0250 CKI CKI

area: 0380

location: S15W02

13720 2024.06.19
2024.06.19
15 43 17 S06E11 0150 DAI DAI

beta-gamma

area: 0260

location: S06E13

S9815 2024.06.19   10 7 N17E11 0030   BXO  
S9816 2024.06.20       S17W43            
13725 2024.06.20
2024.06.23
  9   N18E27 0012   BXO location: N21E23
13721 2024.06.21
2024.06.21
1 3 2 N25E38 0100 HAX CSO area: 0180
13722 2024.06.21
2024.06.21
1 12 2 S12E34 0050 HSX CSO area: 0290

location: S12E37

S9820 2024.06.21       N04W33            
13723 2024.06.22
2024.06.23
7 25 17 S19E54 0180 DSO FAC beta-delta

area: 0430

location: S19E58

13726 2024.06.22
2024.06.23
2 2 1 S04E51 0000 BXO BXO

area: 0007

13724 2024.06.23 1     S14E35 0050 HSX       SWPC decided to split this off from AR 13722. This doesn't make much sense as the latitudinal separation between the southermost location of one of the two penumbrae and the northernmost location of the other penumbra is less than 1 degree. Additionally the two spots share the trailing positive polarity area.
S9824 2024.06.23       S26W21          
S9825 2024.06.23   3 2 S27E70 0020   CRO  
S9826 2024.06.23       N08W21          
S9827 2024.06.24   2 2 S18E74 0300   HHX    
S9828 2024.06.24   3   S19W41 0003   AXX    
S9829 2024.06.24   1   S10W74 0001   AXX    
S9830 2024.06.24   3   S04E76 0006   AXX    
Total spot count: 51 138 66  
Sunspot number: 141 268 156  (total spot count + 10 * number of spotted regions)
Weighted SN: 101 181 110  (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): 154 147 125  

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)
2024.06 184.7 (1)   124.1 (2A) / 155.1 (2B) / 156.3 (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.