Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 13, 2024 at 06:30 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 (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 severe storm levels on May 12. A solar wind shock was observed at ACE at 08:57 UT, likely the arrival of the May 10 CME. The high latitude magnetometer at Andenes recorded unsettled to very severe storm levels. The above 10 MeV proton flux was at 2.5 pfu at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 221.8 - increasing 29.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 159.56. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 159.56 on November 12, 2023). The Potsdam WDC planetary A index was 56 (STAR Ap - based on the mean of three hour interval ap indices: 55.9). Three hour interval K indices: 67442346 (planetary), 58542236 (Boulder), 87443477 (Andenes).

The background x-ray flux is at the class C3 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 18 active regions using 2K resolution (SN: 410) and in 18 active regions using 1K resolution (SN: 312) SDO/HMI images.

Region 13664 [S17W84] was quiet and stable.
Region 13667 [N27W30] decayed slowly and quietly.
Region 13670 [N17W08] decayed slowly and quietly.
Region 13671 [N20E05] was mostly quiet and stable.
Region 13672 [N19E20] decayed slowly and quietly.
Region 13673 [S09E42] was quiet and stable.
Region 13674 [S14E51] was mostly quiet and stable.
Region 13675 [S15W42] has minor polarity intermixing and produced a few flares.
New region 13676 [S21E09] emerged on May 10 and was numbered by SWPC 2 days later as development persisted. The region has a magnetic delta configuration in the central parts and further M class flares are possible.
New region 13677 [S03W38] emerged on May 11 with SWPC numbering the region the following day.
New region 13678 [N09E67] rotated into view on May 11 and received its NOAA number the next day.
New region 13679 [S08E75] rotated into view and may be capable of producing further M class flares.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9676 [S19W73] decayed slowly and is still a huge, very complex spot group. The largest magnetic delta configuration consists of a large area of positive polarity flux sandwiched between negative polarity areas. Another X class flare is possible while the region rotates over the southwest limb.
S9692 [N23W09] was mostly quiet and stable.
S9702 [S08W05] developed slowly and quietly.
New region S9706 [N18E78] rotated into view with a few small spots.
New region S9707 [N13E84] rotated partly into view.
New region S9708 [N12E28] was observed with tiny spots in an old plage area.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C6.4 00:28   S9689 GOES16  
M3.2 00:45 S20W68 S9676 GOES16  
C4.8 01:08   S9676 GOES16  
C7.1 01:55   S9676 GOES16  
C6.5 02:16   S9676 GOES16  
C6.8 02:26   S9700 GOES16  
C8.8 03:06   S9676 GOES16  
C6.4 03:48   S9676 GOES16  
C5.8 04:04   S9676 GOES16  
C4.6 04:32   13675 GOES16  
C5.0 04:45   S9676 GOES16  
C5.5 05:27   S9676 GOES16  
M2.4 05:52 northeast limb S9707 GOES16  
M1.0 06:26   S9676 GOES16  
C6.3 07:01   13676 GOES16  
C5.0 07:59   S9676 GOES16 simultaneous flare at the northeast limb
C8.3 08:40   S9676 GOES16  
C6.2 09:04   13675 GOES16  
C7.9 09:38   S9676 GOES16  
C9.2 10:22 S18W67 S9676 GOES16  
C7.9 10:41   S9676 GOES16  
C7.0 10:57   S9676 GOES16  
C7.0 11:34   13675 GOES16  
M1.6 12:41   S9676 GOES16  
M1.2 12:51   S9676 GOES16  
M1.0 13:47 S09E78 13679 GOES16  
M1.5 13:56 S21W70 S9676 GOES16 simultaneous flare in AR 13675
M1.2 14:21   S9676 GOES16  
C9.1 14:36   S9676 GOES16  
C7.4 14:44   S9676 GOES16  
C5.0 15:08   13675 GOES16  
C7.0 15:26 S20W75 S9676 GOES16  
C7.4 15:31   S9676 GOES16  
C7.3 15:44 northeast limb unassigned GOES16  
C6.3 16:06   13675 GOES16  
X1.0/1F 16:26 S18W72 S9676 GOES16  
M1.0 17:10   13675 GOES16  
M1.1 17:21   13675 GOES16  
C8.5 17:42   S9676 GOES16  
C7.5 18:02   S9676 GOES16 simultaneous flare in AR 13675
C7.6 18:11   S9676 GOES16  
C5.5 19:32   S9676 GOES16  
C7.2 19:47   S9676 GOES16  
C6.8 19:57   S9676 GOES16  
M4.8 20:32 S18W74 S9676 GOES16  
M1.2 21:10   S9676 GOES16  
M1.1 22:06 S16W80 S9676 GOES16  
M1.1 22:18   S9676 GOES16 incorrectly attributed to AR 13676 by SWPC
C6.7 23:06   S9676 GOES16  
M1.0 23:10 S17W77 S9676 GOES16  
C9.5 23:39   13676 GOES16 incorrectly attributed to AR 13664 (S9676) by SWPC

Coronal mass ejections (CMEs)

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.
May 10
: The X3 flare in AR S9676 at 06:54 UT was associated with another 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 major storm levels on May 13-14 due to CMEs from flare activity in AR S9676. Quiet to active conditions are likely on May 15.

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
28 1 1 S19W75 1920 FKC HSX

area: 0140

location: S17W83

SWPC includes AR S9676 in this spot group

13665 2024.05.01
2024.05.02
      S05W75          

location: S06W54

SWPC location is way off

13669 2024.05.02
2024.05.05
      S09W55          

location: S10W47

13668 2024.05.03
2024.05.05
      S15W69           merged with AR S9676 on May 9
13667 2024.05.03
2024.05.04
2 7 5 N27W32 0090 HAX HAX

area: 0160

location: N27W30

S9676 2024.05.05   40 24 S19W73 1850   FKC beta-gamma-delta
13670 2024.05.05
2024.05.06
2 13 6 N19W09 0020 CSO BXO

location: N17W08

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       N15W46            
13671 2024.05.06
2024.05.09
8 16 8 N24W10 0030 DRO DRI

location: N20W09

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

S9682 2024.05.07       N15W56            
S9683 2024.05.07       S26W47            
S9684 2024.05.07       S24W15            
13672 2024.05.08
2024.05.09
4 14 5 N18E17 0080 CSO DAO

location: N19E20

area: 0120

S9687 2024.05.08       S07W37            
S9689 2024.05.08       S10E33          
13675 2024.05.09
2024.05.11
5 24 16 S14W43 0060 DSI DAI area: 0250

location: S15W42

13673 2024.05.09
2024.05.11
1 1 1 S10E41 0030 HSX HSX area: 0050

location: S09E42

S9692 2024.05.09   27 15 N23W09 0070   DRI  
S9693 2024.05.09       N13W45            
S9694 2024.05.09       S04W00            
S9696 2024.05.09       S30W49            
13676 2024.05.10
2024.05.12
10 33 21 S22E09 0130 DAI DSC beta-delta

location: S21E09

area: 0200

13674 2024.05.10 3 18 10 S14E53 0110 CSO CAO area: 0170

location: S14E51

S9700 2024.05.11       S20E37        

 

 
13678 2024.05.11
2024.05.12
1 2 2 N08E65 0010 HSX CAO location: N08E67

area: 0030

S9702 2024.05.11   18 9 S08W05 0040   DRI

 

 
13677 2024.05.11
2024.05.12
1 4 2 S02W38 0010 AXX CRO location: S03W38
S9704 2024.05.11       N10W01          
S9705 2024.05.11       S23E28          
13679 2024.05.12 1 5 3 S09E73 0020 HSX DAO   location: S08E75

area: 0100

S9706 2024.05.12   3 2 N18E78 0050   HAX    
S9707 2024.05.12   1 1 N13E84 0100   HSX    
S9708 2024.05.12   3 1 N12E28 0007   AXX    
Total spot count: 66 230 132  
Sunspot number: 186 410 312  (total spot count + 10 * number of spotted regions)
Weighted SN: 124 307 209  (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): 205 226 250  

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
2024.05 189.3 (1)   55.9 (2A) / 144.3 (2B) / 202.7 (2C) (118.3 projected, +1.2) (46.2)
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.