Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 25, 2024 at 07:40 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 (July 3, 2024)
Solar cycle Solar cycles 23-25 (July 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (July 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 (July 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (July 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 July 24. The high latitude magnetometer at Andenes recorded quiet levels. The above 10 MeV proton flux was at background levels at the time of this update.

Solar flux density measured at 20h UT on 2.8 GHz was 174.8 - decreasing 7.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 164.36. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 164.36 on January 24, 2024). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.3). Three hour interval K indices: 10111131 (planetary), ******** (Boulder), 11122112 (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 19 active regions using 2K resolution (SN: 353) and in 13 active regions using 1K resolution (SN: 214) SDO/HMI images.

AR 13751 [S08W73] decayed losing mature penumbra on the trailing spots, however, the spot group still managed to produce 2 M flares.
AR 13754 [N25W45] decayed slowly and quietly.
AR 13755 [N03W47] was quiet and stable.
AR 13756 [S17W39] was quiet and stable.
AR 13757 [N18W34] decayed slowly and quietly.
AR 13761 [S09W58] decayed slowly and was mostly quiet. C1 flares: C1.6 @ 03:47 UT
AR 13762 [S13E17] was mostly quiet and still has a magnetic delta configuration and M flare potential. The main spot section drifted away from what was previously considered to be the leading spot section. Due to the development of AR S9925 those former spots of AR 13762 will (barring new development) be counted with AR S9925. C1 flares: C1.6 @ 08:40, C1.5 @ 09:48, C1.6 @ 09:57, C1.6 @ 10:39 UT
AR 13763 [N04E46] decayed slowly in the trailing spot section.
AR 13764 [S04E52] was mostly quiet and stable. C1 flare: C1.9 @ 22:28 UT
AR 13765 [S11E61] was mostly quiet and stable. C1 flare: C1.7 @ 16:45 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9925 [S11E08] developed quickly in the leading and trailing spot sections. M class flaring is likely.
S9931 [N19E10] was quiet and stable.
S9941 [N23W06] was quiet and stable.
S9943 [S24W12] was quiet and stable.
S9948 [N29E19] was quiet and stable.
S9949 [S05W24] was quiet and stable.
S9953 [S27E38] was quiet and stable.
S9954 [S02E00] was quiet and stable.
New region S9956 [N20W58] emerged with tiny spots.

A C1.9 flare was recorded at 14:15 UT from a location behind the northwest limb.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
M3.6/2B 07:42 S06W81 13751 GOES16 moderate type II and IV radio sweeps
C3.0 10:57 S11E17 S9925 GOES16  
C2.4 12:02   13751 GOES16  
M3.0/1F 17:21 S07W71 13751 GOES16 moderate type II radio sweep
C6.8 18:26 behind southwest limb 13759 GOES16  
C4.9 19:01   S9925 GOES16  
C3.7 19:24   13762 GOES16  
C2.0 21:04   13751 GOES16  
C2.8 21:48 S09E11 S9925 GOES16  
C2.1 23:29   13762 GOES16  
C2.8 23:36 S14E18 13762 GOES16  
C2.2 23:56   13765 GOES16  

Coronal mass ejections (CMEs)

July 22-24: No obviously Earth directed CMEs were observed.
July 25: A filament eruption began at approximately 00:30 UT and triggered activity in ARs 13762 and AR S9925 and areas to the north of those two spot groups well into the northern hemisphere. The first traces of a CME was observed over the northern limbs and the north pole starting at 00:36 UT. Due to the short time interval between these observations, it is not yet certain if the CME was frontsided or farsided. A full halo CME was observed later on in LASCO imagery.

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

Forecast

The geomagnetic field is expected to be quiet to unsettled on July 24-25 with a possibility of active intervals due to the current CME disturbance. Quiet conditions are likely on July 26-27.

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
13749 2024.07.12
2024.07.13
      S33W80         location: S32W77
13751 2024.07.13
2024.07.13
6 9 4 S08W70 0100 DAO CKO

location: S08W58

area: 0270

13752 2024.07.13
2024.07.14
      N22W69        

location: N24W57

13754 2024.07.14   1   N25W52 0002   AXX

location: N25W45

13760 2024.07.14
2024.07.18
      N20W88            
S9907 2024.07.15       N22W49            
13755 2024.07.15
2024.07.16
1 3 2 N02W49 0010 AXX CRO location: N03W47

area: 0015

13756 2024.07.15
2024.07.16
1 1 1 S17W41 0080 HSX CSO

area: 0100

location: S17W39

13757 2024.07.15
2024.07.16
1 5 1 N17W32 0010 HRX HRX

location: N18W34

area: 0030

S9917 2024.07.16       N19W54            
13761 2024.07.18
2024.07.19
10 15 11 S10W56 0170 DAO EKO

area: 0340

S9925 2024.07.19   42 29 S11E08 0310   EAC beta-gamma-delta

(including leading spot section of AR 13762 due to the complex spot layout)

13762 2024.07.19 29 23 15 S12E10 0230 EAI DAC beta-delta

area: 0200

location: S13E17

SWPC includes AR S9925 in this AR

S9927 2024.07.19       N10W08            
S9928 2024.07.19       S04W27            
S9931 2024.07.20   1 1 N19E10 0003   AXX  
13763 2024.07.21
2024.07.22
2 3 2 N03E48 0100 CSO DSO location: N04E46

area: 0230

S9936 2024.07.21       N22E39            
S9937 2024.07.21       N28E19            
S9938 2024.07.21       S25W31            
S9939 2024.07.21       N09W56            
13764 2024.07.22
2024.07.22
3 16 9 S03E48 0040 HAX EAI

area: 0150

location: S04E65

SWPC has split the easternmost spots into AR 13766

S9941 2024.07.22   12 2 N23W06 0020   AXX  
S9942 2024.07.22       N08W12            
S9943 2024.07.22   5   S17W12 0010   AXX  
S9944 2024.07.22       S03W18            
S9945 2024.07.22       S18W22            
13765 2024.07.23
2024.07.23
1 8 5 S12E59 0110 HSX ESO

area: 0250

location: S11E61

S9948 2024.07.23   5   N29E19 0008   BXO  
S9949 2024.07.23   6 2 S05W24 0013   BXO  
S9950 2024.07.23       N20E06          
S9951 2024.07.23       N13E20          
S9952 2024.07.23       S28E11          
S9953 2024.07.23   3   S27E38 0005   BXO  
S9954 2024.07.23   3   S02E00 0006   BXO  
13766 2024.07.24 6     S08E58 0030 CRO       trailing spot section of AR 13764
S9956 2024.07.24   2   N20W58 0002   BXO    
Total spot count: 60 163 84  
Sunspot number: 160 353 214  (total spot count + 10 * number of spotted regions)
Weighted SN: 101 219 140  (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): 176 194 171  

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  176.4 182.2 160.0 124.6 (-0.7) 8.15
2023.08  153.7 157.6 114.8 124.3 (-0.3) 7.19
2023.09  154.4 156.0 134.2 124.0 (-0.3) 14.26
2023.10  142.8 141.9 99.4 124.8 (+0.8) 8.16
2023.11 153.5 150.2 105.4 127.8 (+3.0) 12.20
2023.12 151.1 146.4 114.2 129.4 (+1.6) 9.60
2024.01 164.6 159.3 126.0 (128.9 projected, -0.5) 5.46
2024.02 172.5 168.3 123.0 (129.4 projected, +0.5) 5.31
2024.03 154.4 152.9 103.7 (130.3 projected, +0.9) 11.03
2024.04 161.3 162.6 136.5 (131.0 projected, +0.7) 9.69
2024.05 187.7
(cycle peak)
191.9 171.7 (SC25 peak) (133.2 projected, +2.2) 23.56
(SC25 peak)
2024.06 184.3 190.2 164.2 (134.9 projected, +1.7) 10.24
2024.07 194.8 (1)   141.7 (2A) / 183.0 (2B) / 211.5 (2C) (134.7 projected, -0.2) (5.4)
2024.08       (134.1 projected, -0.6)  
2024.09       (134.4 projected, +0.1)  
2024.10       (134.3 projected, -0.1)  
2024.11       (132.3 projected, -2.0)  
2024.12       (128.0 projected, -4.3)  
2025.01       (124.0 projected, -4.0)  

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 July 5, 2024

Sunspot counts in June 2024 were almost at the level of May 2024 and the second highest month during solar cycle 25. Looking at the projected activity for the remainder of this year, solar max now looks likely to occur between May and October 2024. A big decrease in sunspot formation in July 2024 and over the next months could change the projected maximum to earlier in 2024 or even to December 2023.

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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.