Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 6, 2024 at 14:30 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 (May 1, 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 levels on June 5. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux was at background levels at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 195.3 - decreasing 37.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 161.61. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 161.61 on December 6, 2023). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.9). Three hour interval K indices: 12222112 (planetary), 12233323 (Boulder), 12223433 (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 17 active regions using 2K resolution (SN: 342) and in 14 active regions using 1K resolution (SN: 234) SDO/HMI images.

Region 13691 [N26W82] decayed further and rotated quietly to the northwest limb.
Region 13695 [N28W67] decayed slowly and could soon become spotless.
Region 13697 [S19W31] decayed slowly losing spots and area, several C and M flares were observed.
Region 13698 [N21W43] was mostly quiet and stable.
Region 13699 [N04W76] decayed slowly and quietly.
Region 13700 [S04W86] rotated partly out of view and was quiet.
Region 13701 [S06W25] decayed slowly and was mostly quiet.
Region 13702 [N17E30] was quiet and stable.
Region 13703 [S08W09] developed slowly becoming a compact region. M class flaring is possible.
Region 13704 [S18E35] was quiet and stable.
Region 13706 [S12E15] decayed slowly and quietly.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9769 [N09E45] developed slowly and quietly.
S9771 [N32E26] was quiet and stable.
New region S9773 [S14W61] emerged with a tiny spot.
New region S9774 [S27E52] emerged with tiny spots.
New region S9775 [S14E71] rotated into view with tiny spots.
New region S9776 [S22E83] rotated partly into view.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment

Coronal mass ejections (CMEs)

June 3-5: 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 northern hemisphere coronal hole (CH1224) rotated across the central meridian on June 4-6.

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 to fair.

Forecast

The geomagnetic field is expected to be at quiet levels on June 6-7. June 8-9 could see a few unsetttled or active intervals due to effects from CH1224.

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
13691 2024.05.24
2024.05.25
2 1 1 N24W86 0030 CRO AXX

location: N26W82

area: 0010

13696 2024.05.25
2024.05.26
      N08W70          

location: N09W50

13695 2024.05.26
2024.05.26
2 1   N26W70 0010 BXO AXX

location: N28W67

are: 0002

13697 2024.05.27
2024.05.28
32 68 31 S18W33 0250 EKC EAC beta-gamma-delta

location: S19W31

area: 0430

13698 2024.05.28
2024.05.30
8 22 15 N21W43 0130 DAI DAI

beta-gamma

area: 0300

13699 2024.05.31
2024.05.31
2 3 1 N03W75 0020 CRO CRO  
13701 2024.05.31
2024.06.01
8 20 10 S05W25 0060 DAI DAO

location: S06W25

area: 0100

13703 2024.05.31
2024.06.03
8 28 23 S07W09 0150 DAI DAC location: S08E04

area: 0480

13700 2024.06.01
2024.06.01
3 1 1 S05W89 0110 DAO HSX

area: 0230

S9760 2024.06.01       N11W01            
13702 2024.06.01
2024.06.02
1 4 2 N17E30 0020 HSX HSX

area: 0160

S9762 2024.06.01       S14E07            
13705 2024.06.02
2024.06.03
1     N21W73 0005 AXX     location: N19W74

spotless

13704 2024.06.02
2024.06.03
1 2 1 S17E34 0030 HSX HAX area: 0050

location: S18E35

S9766 2024.06.02       S21W49            
S9767 2024.06.02       S40W03            
13706 2024.06.03
2024.06.04
5 7 2 S12E15 0020 BXO CRO area: 0025
S9769 2024.06.03   5 3 N09E45 0015   BXO  
S9770 2024.06.04       N15E03          
S9771 2024.06.04   1 1 N32E26 0003   AXX  
S9772 2024.06.04       S05E27          
S9773 2024.06.05   1   S14W61 0001   AXX    
S9774 2024.06.05   2   S27E52 0002   BXO    
S9775 2024.06.05   4 2 S14E71 0008   BXO    
S9776 2024.06.05   2 1 S22E83 0060   CAO    
Total spot count: 73 172 94  
Sunspot number: 193 342 234  (total spot count + 10 * number of spotted regions)
Weighted SN: 119 218 140  (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): 212 188 187  

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
2024.05 187.8 191.9 171.7 (SC25 peak) (126.7 projected, +1.1) 23.6
(current
SC25 peak)
2024.06 188.3 (1)   33.5 (2A) / 201.0 (2B) / 187.6 (2C) (125.9 projected, -0.8) (5.7)
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.