Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 12, 2024 at 08:25 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 very severe to extremely severe storm levels on May 11. Another CME was observed arriving at SOHO at 17:49 UT with a subsequent increase in solar wind speed to above 1000 km/sec. May 11, 2024 now ranks as the geomagnetically second most disturbed day in recorded history. November 13, 1960 is the only day ahead when the daily average Ap was 280. The minimum Kp during the day was 8, the first time this has happened. The high latitude magnetometer at Andenes recorded major to very severe storm levels. The above 10 MeV proton flux was at 42 pfu at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 213.7 - increasing 35.3 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 159.34. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 159.34 on November 11, 2023). The Potsdam WDC planetary A index was 274 (STAR Ap - based on the mean of three hour interval ap indices: 274.3). Three hour interval K indices: 98899888 (planetary), 97997666 (Boulder), 78878687 (Andenes).

The background x-ray flux is at the class C7 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 18 active regions using 2K resolution (SN: 401) and in 15 active regions using 1K resolution (SN: 272) SDO/HMI images.

Region 13664 [S17W71] was quiet and stable.
Region 13667 [N27W17] was quiet and stable.
Region 13670 [N17E02] decayed slowly and quietly.
Region 13671 [N20E05] was quiet and stable.
Region 13672 [N19E34] was mostly quiet and stable.
New region 13673 [S09E55] rotated into view on May 9 and was numbered by SWPC 2 days later.
New region 13674 [S13E66] rotated into view on May 10 and received its NOAA number the following day.
New region 13675 [S15W28] emerged on May 9 with SWPC numbering the region 2 days later when growth intensified.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9676 [S19W60] lost several magnetic delta configurations, as well as area and spots, however, the largest delta remains and consists of a large area of positive polarity flux sandwiched between negative polarity areas. Another X class flare is possible.
S9689 [S10E46] was quiet and stable.
S9692 [N23E04] developed slowly and was mostly quiet.
S9697 [S21E23] developed further and was quiet.
New region S9700 [S20E50] emerged with tiny spots.
New region S9701 [N08E80] emerged near the northeast limb with tiny spots.
New region S9702 [S09E09] emerged with tiny spots.
New region S9703 [S03W25] emerged with tiny spots.
New region S9704 [N10E12] was observed with tiny spots in an old plage area.
New region S9705 [S23E41] emerged with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C7.0 00:28 behind northwest limb 13663 GOES16  
M1.0 01:05   S9676 GOES16  
X5.8/2B 01:23 S15W45 S9676 GOES16 full halo CME
moderate type IV and strong type II radio sweeps
M1.1 03:32   S9676 GOES16  
M1.0 03:59   S9676 GOES16  
M1.0 04:20   S9676 GOES16  
M1.4 04:40   S9676 GOES16  
M1.1 05:24   S9676 GOES16  
M1.1 05:50   S9676 GOES16  
M1.2 07:42   S9676 GOES16  
M1.2 08:07   S9676 GOES16  
M1.3 08:18   13672 GOES16  
M1.4 08:56   S9676 GOES16  
M1.7 09:14   S9676 GOES16  
M3.1 10:18   S9676 GOES16  
M1.6 10:56 behind northwest limb 13663 GOES16 SWPC attributes this to AR 13664 (S9676)
X1.5 11:44   S9676 GOES16  
M2.3 12:38   S9676 GOES16  
M2.0 12:59   S9676 GOES16  
M1.2 13:34   S9676 GOES16  
M1.8/1N 13:49   S9676 GOES16  
M1.3 14:18   S9676 GOES16  
M1.4 14:57   S9676 GOES16  
M6.9 15:13 behind northeast limb   GOES16  
M8.8/2N 15:25 S15W49 S9676 GOES16  
M2.8 16:55   S9676 GOES16  
M1.1 17:41   S9676 GOES16  
C6.6 19:01   S9676 GOES16  
C5.3 19:21   S9676 GOES16  
C5.5 19:32   S9676 GOES16 simultaneous flare in AR 13670
C7.2 19:47 N16E56 13672 GOES16  
C6.5 20:04   S9676 GOES16  
M1.2 20:41   S9676 GOES16  
C9.4 21:07   S9676 GOES16  
C7.3 21:42   S9676 GOES16  
C7.8 21:58   S9676 GOES16  
C6.2 22:39 behind northeast limb   GOES16  
C6.6 23:29   S9676 GOES16  

Coronal mass ejections (CMEs)

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.
May 9
: A full halo CME  was observed following an X2 flare in AR S9676.

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) was 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 very poor to useless. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be at active to severe storm levels on May 12-14 due to inbound CMEs from flare activity in AR S9676.

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
43 1 1 S18W62 2100 FKC HSX

area: 0140

location: S17W71

SWPC includes AR S9676 in this spot group

13665 2024.05.01
2024.05.02
      S05W60        

location: S06W41

SWPC location is way off

13669 2024.05.02
2024.05.05
      S09W41        

location: S10W34

13668 2024.05.03
2024.05.05
      S15W55           merged with AR S9676 on May 9
S9670 2024.05.03       N04W50            
13667 2024.05.03
2024.05.04
1 4 3 N27W18 0140 HSX HAX

area: 0230

location: N27W17

S9672 2024.05.03       S33W47            
S9676 2024.05.05   81 49 S19W60 2360   FKC beta-gamma-delta
13670 2024.05.05
2024.05.06
4 15 5 N18E02 0030 CSO BXO

location: N17E02

S9679 2024.05.06       N15W33            
13671 2024.05.06
2024.05.09
7 11 7 N24E04 0030 CRO DRO

location: N20E05

SWPC location on May 10 was N19E17, the new location seems to be that of AR S9692

S9682 2024.05.07       N15W43            
S9683 2024.05.07       S26W34            
S9684 2024.05.07       S24W02            
13672 2024.05.08
2024.05.09
4 16 10 N18E30 0090 DAO DSO beta-gamma

location: N19E34

area: 0130

S9687 2024.05.08       S07W24            
S9689 2024.05.08   3 1 S10E46 0005   BXO  
13675 2024.05.09
2024.05.11
5 12 6 S15W29 0030 CRO DAO area: 0100

location: S15W28

13673 2024.05.09
2024.05.11
1 1 1 S09E54 0030 HSX HSX area: 0050

location: S09E55

S9692 2024.05.09   28 15 N23E04 0070   DRI  
S9693 2024.05.09       N13W32          
S9694 2024.05.09       S04E13            
S9695 2024.05.09       S21W51          
S9696 2024.05.09       S30W36            
S9697 2024.05.10   24 16 S21E23 0130   DRI  
13674 2024.05.10 3 11 5 S14E64 0080 CSO DAO area: 0170

location: S13E66

S9700 2024.05.11   2   S20E50 0002   AXX  

 

 
S9701 2024.05.11   3 1 N08E80 0006   BXO  

 

 
S9702 2024.05.11   4 1 S09E09 0008   BXO  

 

 
S9703 2024.05.11   2 1 S03W25 0006   BXO  

 

 
S9704 2024.05.11   2   N10E12 0002   BXO  

 

 
S9705 2024.05.11   1   S23E41 0002   AXX  

 

 
Total spot count: 68 221 122  
Sunspot number: 148 401 272  (total spot count + 10 * number of spotted regions)
Weighted SN: 109 270 171  (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): 163 221 218  

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
2024.05 186.3 (1)   49.9 (2A) / 140.5 (2B) / 198.8 (2C) (118.3 projected, +1.2) (45.0)
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.