Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 14, 2024 at 05:35 UT. Minor update posted at  17:00 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 to major storm levels on May 13. The high latitude magnetometer at Andenes recorded quiet to major storm levels. The above 10 MeV proton flux was at 83 pfu at the end of the day, slowly increasing.

Solar flux density measured at 20h UT on 2.8 GHz was 215.4 - increasing 16.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 159.77. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 159.77 on November 13, 2023). The Potsdam WDC planetary A index was 29 (STAR Ap - based on the mean of three hour interval ap indices: 29.0). Three hour interval K indices: 66334332 (planetary), 67434333 (Boulder), 36433222 (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 21 active regions using 2K resolution (SN: 450) and in 16 active regions using 1K resolution (SN: 267) SDO/HMI images.

Region 13667 [N27W42] decayed slowly and quietly.
Region 13670 [N15W23] was quiet and stable.
Region 13671 [N19W20] was mostly quiet and stable.
Region 13672 [N19E07] decayed slowly and was mostly quiet.
Region 13673 [S09E29] was quiet and stable.
Region 13674 [S13E39] was mostly quiet and stable.
Region 13675 [S14W56] decayed slowly and was mostly quiet.
Region 13676 [S20W06] decayed and lost the magnetic delta configuration.
Region 13677 [S02W51] decayed slowly and quietly.
Region 13678 [N09E52] was quiet and stable.
Region 13679 [S09E62] developed slowly and was mostly quiet.
New region 13680 [N18E65] rotated into view on May 12 and was numbered the next day by SWPC.
New region 13681 [S08W20] emerged on May 11 with SWPC numbering the region 2 days later. Slow decay was observed on May 13.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9676 [S19W84] rotated partly out of view producing many M and C flares. An X1.6 flare was recorded at 02:09 UT on May 14. Further X class proton flares are possible today and tomorrow as the spot group rotates over and behind the southwest limb.
S9689 [S09E17] reemerged with tiny spots.
S9692 [N23W22] was mostly quiet and stable.
S9700 [S23E23] reemerged with tiny spots.
S9705 [S24E14] reemerged with tiny spots.
S9707 [N13E72] was quiet and stable.
S9708 [N17E22] was quiet and stable.
New region S9710 [N05W12] emerged with a tiny spot.

Minor update posted at 17:00 UT: AR S9676 produced the largest flare of SC25, an X8.7 flare at 16:51 UT. This could be a significant proton flare as well, the next hours will tell.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C6.4 00:09   S9676 GOES16 simultaneous flare in AR 13676
C6.5 00:32   S9676 GOES16  
C6.0 00:59   13671 GOES16  
C9.4 01:09   S9676 GOES16 simultaneous flare in AR 13671
C9.5 01:30   S9676 GOES16  
M1.2 01:33 S20W72 S9676 GOES16  
C7.9 01:42   S9676 GOES16  
C6.5 02:07   S9676 GOES16  
C4.8 02:30   S9676 GOES16 simultaneous flare in AR 13676
C5.8 02:46   S9676 GOES16  
C5.0 03:01   S9676 GOES16  
C4.6 03:11   S9676 GOES16  
C4.3 03:50   S9676 GOES16  
C5.1 04:03   S9676 GOES16  
C4.1 04:15   S9676 GOES16  
C3.6 05:08   S9676 GOES16  
C4.3 05:32   S9676 GOES16  
C5.3 05:47   S9676 GOES16  
C5.3 05:57   S9676 GOES16  
C5.4 06:11   S9676 GOES16  
C4.5 06:23   S9676 GOES16  
C4.3 07:07   S9676 GOES16 simultaneous flare in AR 13671
C6.4 07:35 S20E06 13676 GOES16 simultaneous flare in AR S9676
M1.3 08:20 S19W80 S9676 GOES16  
M1.4 08:29   S9676 GOES16  
M2.2 09:12   13676 GOES16  
M4.9 09:33   S9676 GOES16  
M6.6 09:44   S9676 GOES16 LDE, full halo CME
moderate type II and IV radio sweeps
M3.7 13:11   S9676 GOES16  
M1.6 13:32   S9676 GOES16  
M1.3 13:51   13676 GOES16  
M1.4 14:07   13676 GOES16  
M1.5 14:15   S9676 GOES16  
C8.8 15:25   13676 GOES16  
C7.6 16:02   S9676 GOES16  
C6.5 16:33   S9676 GOES16  
M1.0 17:47   13674 GOES16  
M1.0 18:09   13674 GOES16  
M1.1 18:48   S9676 GOES16  
C5.3 19:57   S9676 GOES16  
C5.4 20:52   S9676 GOES16  
C5.1 21:21   S9676 GOES16  
M1.6 21:59   S9676 GOES16  
C5.2 22:29   S9676 GOES16  

Coronal mass ejections (CMEs)

May 13: A full halo CME was observed after the M6.6 long duration event peaking at 09:44 UT in AR S9676. This CME could reach Earth on May 15 and cause unsettled to major geomagnetic storming.
May 12
: Several CMEs were observed during the first half of the day. While none of them are obviously earthbound, there's a chance of a weak CME impact on May 15.
May 11
: The X5 flare in AR S9676 at 01:23 UT was associated with a bright halo CME.

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 positions.

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 at quiet to minor storm levels on May 14. The likely arrival of another CME on May 15 could cause unsettled to major storm intervals that day and quiet to minor storm on May 16.

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
13664 2024.04.30
2024.05.01
15     S19W87 1170 FKC    

rotated out of view

location: S17W96

SWPC includes AR S9676 in this spot group

13669 2024.05.02
2024.05.05
      S09W69          

location: S10W60

13668 2024.05.03
2024.05.05
      S15W83           merged with AR S9676 on May 9
13667 2024.05.03
2024.05.04
4 5 3 N27W46 0080 HAX HAX

area: 0140

location: N27W42

S9676 2024.05.05   11 7 S19W84 1400   EKC beta-gamma-delta
13670 2024.05.05
2024.05.06
5 12 4 N19W23 0020 DAO BXO

location: N15W23

SWPC has moved AR 13670 to the position of AR 13671 and AR 13671 to the position of AR S9692. What a mess!

S9679 2024.05.06       N15W59            
13671 2024.05.06
2024.05.09
6 21 13 N24W24 0020 DRO DRI

location: N19W20

SWPC location on May 10 was N19E17, then they changed that to the location of AR S9692

area: 0090

S9684 2024.05.07       S24W28            
13672 2024.05.08
2024.05.09
4 19 9 N19E03 0060 CSO CAO

location: N19E07

area: 0100

S9687 2024.05.08       S07W50            
S9689 2024.05.08   10   S09E17 0020   AXX    
13675 2024.05.09
2024.05.11
13 20 10 S05W57 0140 DSI DAI

location: S14W56

SWPC location is probably a type

13673 2024.05.09
2024.05.11
1 4 2 S11E27 0010 HSX CAO area: 0040

location: S09E29

S9692 2024.05.09   23 12 N23W22 0050   DRI  
S9693 2024.05.09       N13W58            
S9694 2024.05.09       S04W13            
13676 2024.05.10
2024.05.12
12 29 15 S21W05 0100 DSI DSC beta-gamma

location: S20W06

area: 0160

13674 2024.05.10 6 27 9 S11E39 0090 CAO CAO area: 0140

location: S13E39

S9700 2024.05.11   4   S23E23 0005   AXX    
13678 2024.05.11
2024.05.12
1 9 3 N09E51 0010 HRX CRO location: N09E52

area: 0015

13681 2024.05.11
2024.05.13
3 6 3 S07W20 0012 AXX BXO  
13677 2024.05.11
2024.05.12
  1   S02W53 0001   AXX location: S02W51
S9704 2024.05.11       N10W14            
S9705 2024.05.11   3   S24E14 0007   AXX    
13679 2024.05.12 4 15 8 S08E59 0060 DAO EAO location: S09E62

area: 0300

13680 2024.05.12
2024.05.13
3 4 4 N17E65 0030 DAO HAX area: 0050

location: N18E65

S9707 2024.05.12   5 3 N13E72 0100   DSO  
S9708 2024.05.12   11 2 N17E22 0020   AXX  
S9710 2024.05.13   1   N05W12 0001   AXX    
Total spot count: 77 240 107  
Sunspot number: 207 450 267  (total spot count + 10 * number of spotted regions)
Weighted SN: 138 304 171  (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): 228 248 214  

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) 9.69
2024.05 191.3 (1)   62.5 (2A) / 149.2 (2B) / 205.9 (2C) (118.3 projected, +1.2) (44.8)
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.