Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 8, 2024 at 03:40 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 (May 1, 2024)
Solar cycle Solar cycles 23-25 (May 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (May 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 (May 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (May 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 May 7. 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 203.6 - increasing 72.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 158.67. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 158.71 on October 28, 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: 12112212 (planetary), ******** (Boulder), 13223433 (Andenes).

The background x-ray flux is at the class C5 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 16 active regions using 2K resolution (SN: 381) and in 12 active regions using 1K resolution (SN: 242) SDO/HMI images.

Region 13661 [N23W40] decayed slowly and quietly.
Region 13663 [N25W58] decayed further losing spot and area. There is still a magnetic delta configuration in the trailing spot section and further major flares are possible. An X1.0 flare was recorded at 01:41 UT on May 8.
Region 13664 [S19W15] lost parts of its trailing spots to AR S9676 as that region continued its extreme development. Further M class flares are possible due to a magnetic delta configuration in the trailing spot section.
Region 13665 [S06E12] was quiet and stable.
Region 13666 [N07W39] was quiet and stable.
Region 13667 [N26E33] was quiet and stable.
Region 13668 [S16E00] gained a few spots and was mostly quiet. The leader spots continue to interact with the northeastern spots of AR S9676.
Region 13669 [S09E17] decayed slowly and quietly.
Region 13670 [N17E56] gained a trailing spot and was quiet.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9660 [N09W22] was quiet and stable.
S9676 [S20W07] developed quickly and merged with what was formerly the trailing spots of AR 13664. Due to extreme complexity and many magnetic delta configurations the spot group flares almost continuously. Major flares are possible. This is currently the largest spot group in area of SC25.
S9679 [N15E19] was quiet and stable.
S9680 [N20E60] was quiet and stable.
New region S9682 [N15E09] emerged with a tiny spot.
New region S9683 [S26E18] emerged with tiny spots.
New region S9684 [S24E50] emerged with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
M1.1 00:09   13664 GOES16  
M1.1 00:30   S9676 GOES16  
M2.6 00:58 N27W40 13663 GOES16  
M2.2 01:14   S9676 GOES16  
M1.6 01:34   S9676 GOES16  
C5.9 02:25   13663 GOES16  
C6.7 02:34   S9676 GOES16  
C6.2 02:57   13663 GOES16  
C9.4 03:12   S9676 GOES16  
C9.6 03:20   S9676 GOES16  
C5.7 03:37   S9676 GOES16  
C4.2 03:59   S9676 GOES16  
C4.7 04:09   S9676 GOES16 simultaneous flare in AR 13663
C4.9 04:28   13664 GOES16 simultaneous flares in ARs 13663 and S9676
C4.5 04:34   S9676 GOES16 simultaneous flare in AR 13663
C3.7 04:57   S9676 GOES16  
C3.8 05:36   S9676 GOES16  
C5.7 05:46   S9676 GOES16 simultaneous flare in AR 13663
M5.1 06:16   13663 GOES16  
M2.2 06:42   13664 GOES16  
M1.4 07:03   S9676 GOES16 simultaneous flare in AR 13663
M1.5 07:17   S9676 GOES16  
M1.1 07:33   13663 GOES16  
M1.3 08:23   13663 GOES16  
M1.4 08:31   S9676 GOES16  
C9.2 08:42   S9676 GOES16 simultaneous flare in AR 13663
C5.5 09:17   S9676 GOES16  
C5.5 09:54   13663 GOES16  
C9.5/1F 10:42   13663 GOES16 simultaneous flare in AR S9676
M2.4/2N 11:50 S18E03 S9676 GOES16  
M1.5 12:54   13663 GOES16  
M1.0 13:25   13663 GOES16  
M1.0 13:35   13663 GOES16  
C7.5 13:55   S9676 GOES16  
C4.7 14:40   13663 GOES16  
C3.8 15:17   13663 GOES16  
C5.0 15:35   S9676 GOES16  
C4.7 15:43   13663 GOES16  
M8.2 16:30   13663 GOES16  
C7.2 17:38   S9676 GOES16  
C5.3 17:52   S9676 GOES16  
C5.6 18:29   13663 GOES16 simultaneous flare in AR S9676
C8.4 18:56   S9676 GOES16  
C6.5 19:16   S9676 GOES16  
C8.8 20:09   S9676 GOES16  
M2.1 20:22   13664 GOES16  
M1.2 20:47   S9676 GOES16  
M1.2 20:52   S9676 GOES16  
M1.1 21:06   13663 GOES16  
M1.1 21:11   13663 GOES16 simultaneous flare in AR S9676
M3.3 21:26   13663 GOES16  
M3.2 21:53   S9676 GOES16  
M3.3 21:59   13663 GOES16  
M1.5 23:04   13663 GOES16 simultaneous flare in AR 13663
M1.4 23:24   S9676 GOES16  
M1.6 23:31   S9676 GOES16  

Coronal mass ejections (CMEs)

May 5: LASCO imagery was unavailable.
May 6-7
: No obviously Earth directed CMEs were 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 (CH1221) will become Earth facing on May 8-9.

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 May 8-10. Quiet to active conditions are possible on May 11-12 due to effects from CH1221

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
13660 2024.04.26
2024.04.27
      N11W75           location: N10W69
13662 2024.04.27
2024.04.29
      N27W85        

location: N29W84

13661 2024.04.28
2024.04.29
1 5 1 N22W42 0010 AXX AXX  
13663 2024.04.29
2024.04.30
15 34 21 N25W57 0400 FKC FAC beta-delta

area: 0680

location N25W58

13664 2024.04.30
2024.05.01
37 30 19 S20W09 0630 FKC DAC beta-gamma-delta

area: 0420

location: S19W15

SWPC includes AR S9676 in this spot group

S9660 2024.04.30   6 1 N09W22 0010   BXO  
S9661 2024.04.30       S22W54            
S9662 2024.05.01       N20W59            
13665 2024.05.01
2024.05.02
  6   S05W00 0010   BXO

location: S06E12

13666 2024.05.02
2024.05.03
2 9 6 N07W40 0080 HSX CAO

area: 0160

location: N07W39

13669 2024.05.02
2024.05.05
1 1   S09E15 0010 AXX AXX area: 0003

location: S09E17

S9668 2024.05.02       N12W50            
13668 2024.05.03
2024.05.05
6 31 21 S16E01 0030 CSO DRI see AR 13664 beta-gamma

area: 0100

location: S16E00

S9670 2024.05.03       N04E02            
13667 2024.05.03
2024.05.04
1 2 1 N26E32 0150 HSX HSX

area: 0240

location: N26E33

S9672 2024.05.03       S33E05            
S9673 2024.05.04       S11W35            
S9674 2024.05.04       N01W38            
S9675 2024.05.05       S10W30            
S9676 2024.05.05   81 46 S20W07 2060   EKC see AR 13664 beta-gamma-delta
13670 2024.05.05
2024.05.06
1 2 2 N16E55 0040 HSX DSO area: 0070

location: N17E56

S9679 2024.05.06   2   N15E19 0005   BXO  
S9680 2024.05.06   8 2 N20E60 0012   BXO  
S9681 2024.05.06       S31W31          
S9682 2024.05.07   1 1 N15E09 0002   AXX    
S9683 2024.05.07   2   S26E18 0003   BXO    
S9684 2024.05.07   1 1 S24E50 0002   AXX    
Total spot count: 64 221 122  
Sunspot number: 144 381 242  (total spot count + 10 * number of spotted regions)
Weighted SN: 104 259 160  (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): 158 210 194  

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
(current
SC25 peak)
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)
(SC25 solar max candidate)
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 (125.2 projected, +0.4) 12.20
2023.12 151.1 146.4 114.2 (121.9 projected, -3.3) 9.60
2024.01 164.6 159.3 123.0 (118.5 projected, -3.4) 5.46
2024.02 172.5 168.3 124.7 (117.7 projected, -0.8) 5.31
2024.03 154.4 152.9 104.9 (117.1 projected, -0.6) 11.03
2024.04 161.3 162.6 136.5 (117.1 projected, -0.0) 9.5
2024.05 164.6 (1)   30.0 (2A) / 132.9 (2B) / 184.6 (2C) (118.3 projected, +1.2) (13.8)
2024.06       (117.4 projected, -0.9)  
2024.07       (115.7 projected, -1.7)  
2024.08       (113.8 projected, -1.9)  
2024.09       (112.5 projected, -1.3)  
2024.10       (111.1 projected, -1.4)  
2024.11       (108.6 projected, -2.5)  

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 April 28, 2024

The big increase in sunspot counts during the April 14-27 interval caused a major uptick in the smoothed SNs and solar flux. It's not yet clear when the next peak will be, anytime between October 28 and December 20, 2023 looks possible. The 365d smoothed solar flux exceeded the June 27 peak on October 28, while the 365d smoothed ISN and NOAA SN both exceeded the June 2023 peak in late October 2023. It should be noted that the current peak using 13-month smoothing is still in June 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.