Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 15, 2024 at 05:40 UT. Minor update added at 15:05 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 unsettled levels on May 14. The high latitude magnetometer at Andenes recorded quiet to unsettled levels. The above 10 MeV proton flux was at 26 pfu at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 219.8 - increasing 3.3 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 160.01. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 160.01 on November 14, 2023). The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.6). Three hour interval K indices: 12132221 (planetary), 22123322 (Boulder), 21133231 (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: 354) and in 17 active regions using 1K resolution (SN: 252) SDO/HMI images.

Region 13667 [N27W55] was quiet and stable.
Region 13670 [N14W38] decayed slowly and quietly.
Region 13671 [N19W33] developed slowly and was mostly quiet.
Region 13672 [N19W05] decayed slowly and quietly.
Region 13673 [S09E17] decayed slowly and quietly.
Region 13674 [S13E26] was mostly quiet and stable.
Region 13675 [S15W70] decayed slowly and quietly.
Region 13676 [S20W20] decayed further and was quiet.
Region 13678 [N09E39] decayed slowly and quietly.
Region 13679 [S09E48] developed slowly and could produce M flares.
Region 13680 [N17E50] decayed slowly and quietly.
Region 13681 [S10W32] decayed slowly and quietly.
New region 13682 [N13E58] rotated into view on May 12 and was numbered by SWPC 2 days later. Further M class flaring is possible.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9689 [S11W03] was quiet and stable.
S9692 [N22W33] decayed slowly and quietly.
S9700 [S24E07] developed slowly and quietly as new flux emerged.
S9708 [N16E13] was quiet and stable.
New region S9711 [N27W04] emerged with a tiny spot.

Minor update posted at 15:05 UT: It's rare that 2 different spot groups produce X class flares the same day. AR S9676 behind the southwest limb was the source of an X3.4 flare at 08:37 UT while newly numbered AR S9714 at the southeast limb was the origin of an X2.9 flare at 14:38 UT. The latter spot group is rotating into view and produced several flares yesterday while behind the limb.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
M2.5 01:48   13671 GOES16  
X1.7 02:09   S9676 GOES16 moderate type II radio sweep
C8.1 03:27   S9676 GOES16  
C6.5 04:08   13679 GOES16  
C6.5 04:57   S9676 GOES16  
C6.6 05:09   S9676 GOES16  
C6.8 05:29 behind southeast limb   GOES16  
C8.2 08:27   S9676 GOES16  
M1.1 10:08 spotless plage northeast quadrant   GOES16  
C8.4 11:13   S9676 GOES16  
C8.1 11:25   S9676 GOES16  
C7.1 12:10   S9676 GOES16  
X1.2 12:55   S9676 GOES16 moderate type II radio sweep
C5.9 14:52   S9676 GOES16  
C9.6 15:28   S9676 GOES16  
C6.0 16:07   13679 GOES16  
X8.7 16:51 S19W90 S9676 GOES16 partial halo CME, largest flare of SC25
modewrate type II and weak type IV radio sweeps
M4.4/2N 17:38 N19E72 13682 GOES16 moderate type II radio sweep, CME
M3.9 18:08   13682 GOES16  
M1.2 20:01   13679 GOES16  
C6.3 22:14 behind southeast limb   GOES16  
C7.2 23:14   S9676 GOES16 incorrectly attributed to AR 13679 by SWPC
C6.3 23:56 behind southeast limb   GOES16 simultaneous flare in AR S9676

Coronal mass ejections (CMEs)

May 14: A partial halo CME was observed after the X8.7 flare in AR S9676. Due to a flare in AR 13682 and a subsequent CME near the east limb a little later, it was impossible to determine if the first CME was a full halo CME. Any effects from the CME could reach Earth on May 17.
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.

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 15-17 assuming that the May 12 and 13 CMEs reach Earth. Quiet to active is likely on May 17.

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
13669 2024.05.02
2024.05.05
      S09W83          

location: S10W73

13667 2024.05.03
2024.05.04
4 1 1 N27W60 0080 HSX HSX

area: 0110

location: N27W55

13670 2024.05.05
2024.05.06
5 5 2 N19W37 0060 DAO BXO

location: N14W38

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

13671 2024.05.06
2024.05.09
6 17 10 N23W38 0020 CRO DAI

location: N19W33

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

area: 0140

S9684 2024.05.07       S24W41            
13672 2024.05.08
2024.05.09
4 13 5 N19W11 0060 CSO CAO

location: N19W05

area: 0080

SWPC location is way off

S9689 2024.05.08   5   S11W03 0012   AXX  
13675 2024.05.09
2024.05.11
8 7 3 S15W71 0030 DRO DRO

location: S15W70

13673 2024.05.09
2024.05.11
1 4 3 S09E13 0010 HRX CSO area: 0040

location: S09E17

S9692 2024.05.09   13 8 N22W33 0040   DRI  
S9694 2024.05.09       S04W26            
13676 2024.05.10
2024.05.12
9 13 5 S22W19 0120 DSI DSC

location: S20W20

area: 0160

13674 2024.05.10 11 27 16 S12E25 0140 CSO DAO area: 0170

location: S13E26

S9700 2024.05.11   15 6 S24E07 0050   DRI  
13678 2024.05.11
2024.05.12
3 2 1 N09E37 0010 AXX BXO location: N09E39
13681 2024.05.11
2024.05.13
  1 1 S07W35 0005   AXX  
13677 2024.05.11
2024.05.12
      S02W67         location: S02W64
S9704 2024.05.11       N10W27            
S9705 2024.05.11       S24E01          
13679 2024.05.12 6 15 6 S09E46 0230 DSO EKI beta-gamma

location: S09E48

area: 0390

13680 2024.05.12
2024.05.13
3 9 3 N18E51 0010 DAO CRO area: 0030

location: N17E50

13682 2024.05.12
2024.05.14
5 16 8 N15E59 0130 DAO CAO location: N13E58
S9708 2024.05.12   10 3 N16E13 0025   BXO  
S9710 2024.05.13       N05W25          
S9711 2024.05.14   1 1 N27W04 0003   AXX    
Total spot count: 65 174 82  
Sunspot number: 185 354 252  (total spot count + 10 * number of spotted regions)
Weighted SN: 114 231 139  (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): 204 195 202  

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
2024.05 193.3 (1)   68.5 (2A) / 151.7 (2B) / 207.5 (2C) (118.3 projected, +1.2) (42.1)
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.