Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 17, 2024 at 05:30 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 to active levels on June 16 under the influence of weak CME effects. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at  background levels at the end of the day. Solar wind speed increased after 03h UT on June 17 at ACE, probably the arrival of a high speed stream from CH1226.

Solar flux density measured at 20h UT on 2.8 GHz was 167.3 - decreasing 32.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 162.21. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 162.21 on December 17, 2023). The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.9). Three hour interval K indices: 31233334 (planetary), 21032332 (Boulder), 41233553 (Andenes).

The background x-ray flux is at the class C1 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 302) and in 8 active regions using 1K resolution (SN: 165) SDO/HMI images.

Region 13708 [S20W57] decayed slowly and quietly.
Region 13709 [S08W52] decayed slowly and quietly.
Region 13711 [S12W38] gained a few spots and was quiet.
Region 13712 [S26E01] expanded further and produced many C flares. Some decay was observed in the trailing spot section. While there are still multiple magnetic delta configurations within the spot group, they decreased in size and the region looks less magnetically complex compared to one day ago. A major flare remains a possibility. C1 flares: C1.9 @ 00:53. C1.8 @ 03:52, C1.9 @ 12:05, C1.9 @ 14:19, C1.5 @ 16:38, C1.8 @ 20:10 UT
Region 13713 [S13E18] decayed further and was mostly quiet.
Region 13714 [N14W28] was quiet and stable.
Region 13715 [N18W01] reemerged with tiny spots.
Region 13716 [N10E09] gained area and became a compact spot group. Although the spot group currently is not very complex, an M flare is possible
Region 13717 [N08W45] decayed slowly and quietly.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
New region S9803 [S06W17] was observed with tiny spots in an old plage area.
New region S9804 [N17E22] emerged with tiny spots.
New region S9805 [S11E67] rotated into view with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.2 01:11 S24E10 13712 GOES16  
C3.7 02:01   13712 GOES16  
C2.9 02:20   13712 GOES16  
C2.6 02:40   13712 GOES16  
C2.9 03:04   13713 GOES16  
C2.3 03:20   13712 GOES16  
C2.3 04:09   13712 GOES16  
C2.4 04:44   13712 GOES16  
C2.6 04:54   13712 GOES16  
C3.3 05:21   13712 GOES16  
C3.2 05:31   13712 GOES16  
          SWPC GOES16 data gap 06:00 - 10:50
C2.8 11:28   13712 GOES16  
C2.3 11:47 S25E12 13712 GOES16  
C2.0 11:59   13712 GOES16  
C2.1 12:31   13712 GOES16  
C3.1 12:39 S24E09 13712 GOES16  
C4.0 12:57 S25E12 13712 GOES16  
C2.8 14:10   13712 GOES16  
C3.2/1F 14:39 S24E09 13712 GOES16  
C4.9 15:15   13712 GOES16  
C6.7/1F 15:46 S25E05 13712 GOES16  
C3.1 16:04   13712 GOES16  
C4.7 16:11   13712 GOES16  
C3.3 17:01   13712 GOES16  
C4.0 17:09 N10E13 13716 GOES16  
C3.5 17:16   13712 GOES16  
C2.0 18:32   13716 GOES16 incorrectly attributed to AR 13712 by SWPC
C2.2 18:39   13712 GOES16  
C3.5 19:15   13712 GOES16  
C2.4 19:32   13712 GOES16  
C5.2 20:20   13712 GOES16  
C2.3 20:44   13712 GOES16  
C6.6/1N 21:24 S25W00 13712 GOES16  
C2.3 21:42   13712 GOES16  
C2.2 21:58   13716 GOES16  
C4.4 22:28 S24E01 13712 GOES16  

Coronal mass ejections (CMEs)

June 14-16: No obviously Earth directed CME 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]

A positive polarity trans equatorial coronal hole (CH1226) was Earth facing on June 13-14.

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.

Forecast

The geomagnetic field is expected to be quiet to unsettled on June 17-18 due to effects CH1226. Quiet conditions are likely on June 19-20.

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
13707 2024.06.05
2024.06.06
      S14W75            
13708 2024.06.05
2024.06.06
1 3 1 S21W58 0020 HSX CAO area: 0030

location: S20W57

13709 2024.06.06
2024.06.07
3 8 4 S08W53 0010 CAO CAO area: 0070

location: S08W52

13711 2024.06.07
2024.06.09
5 15 7 S11W42 0020 HRX BXO

area: 0030

13714 2024.06.08
2024.06.12
  9 4 N14W32 0020   AXX location: N14W28
S9791 2024.06.10       S24W45            
13715 2024.06.11
2024.06.12
  4   N17W07 0006   BXO   location: N18W01
13712 2024.06.11
2024.06.12
31 56 29 S26E01 1000 EKC EKC beta-gamma-delta

area: 1070

13713 2024.06.11
2024.06.12
18 27 12 S15E15 0200 ESO ESI beta-gamma

location: S13E18

S9796 2024.06.11       N27W17            
S9798 2024.06.11       S20W32            
13716 2024.06.12 20 41 22 N09E09 0180 DAC DAC beta-gamma

area: 0500

location: N10E09

S9800 2024.06.13       N29W12            
13717 2024.06.14
2024.06.15
4 11 6 N08W47 0010 BXO BXI  
S9802 2024.06.15       S32E39          
S9803 2024.06.16   5   S06W17 0007   BXO    
S9804 2024.06.16   2   N17E22 0002   BXO    
S9805 2024.06.16   1   S11E67 0001   AXX    
Total spot count: 82 182 85  
Sunspot number: 152 302 165  (total spot count + 10 * number of spotted regions)
Weighted SN: 110 212 115  (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): 167 166 132  

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)
2024.06 179.5 (1)   83.1 (2A) / 155.9 (2B) / 160.5 (2C) (125.9 projected, -0.8) (8.9)
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.