Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 4, 2024 at 07:10 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 (September 1, 2024)
Solar cycle Solar cycles 23-25 (October 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (October 1, 2024) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (August 1, 2020) POES auroral activity level [October 2009 - December 2012]
  Comparison of cycles 21-25 (October 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (October 1, 2024) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (June 17, 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 October 3. Solar wind speed at SOHO ranged between 341 and 397 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled 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 311.9 - increasing 63.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 177.49. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 177.49 on April 4, 2024). The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.0). Three hour interval K indices: 11223122 (planetary), 01223332 (Boulder), 21113122 (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 20 active regions using 2K resolution (SN: 510) and in 16 active regions using 1K resolution (SN: 311) SDO/HMI images.

AR 13835 [S20W79] reemerged with a tiny spot.
AR 13836 [S13W61] was mostly quiet and stable.
AR 13839 [S14W20] was quiet and stable.
AR 13841 [N13W22] decayed quickly and lost the magnetic delta configuration. Flare activity decreased strongly after noon.
AR 13842 [S16W08] gained area in the leading spot section. The largest penumbra has multiple magnetic delta configurations and another X class flare is possible.
AR 13843 [S09W42] produced a major flare and has a magnetic delta configuration in the trailing spot section.
AR 13844 [S15W30] displayed impressive growth and redeveloped a magnetic delta configuration. A major flare is possible.
AR 13845 [N17W68] developed slowly and quietly.
AR 13847 [S28E35] decayed slowly and quietly.
AR 13848 [N13E56] was mostly unchanged and less active than during the previous day.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S10169 [S21W39] was quiet and stable.
S10171 [S04W15] was quiet and stable.
S10177 [N16W53] reemerged with tiny spots.
S10186 [N17E11] was quiet and stable.
S10189 [N10W09] was quiet and stable.
S10190 [S17E09] was quiet and stable.
New region S10191 [S06E78] rotated into view with large spots. It is not yet clear if this is one or two spot groups.
New region S10192 [S10W00] emerged with tiny spots.
New region S10193 [S22E35] was observed with tiny spots in an old plage area.
New region S10194 [S12E47] was observed with tiny spots in an old plage area.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C4.9 01:06   13842 GOES16  
C5.9 01:58   13842 GOES16  
M1.1 02:34 N13W08 13841 GOES16  
C8.1 03:00   13844 GOES16  
C8.0 03:11   13841 GOES16  
M1.5 03:40   13842 GOES16  
C6.7 04:35   13848 GOES18 simultaneous flares in ARs 13842 and 13844
C9.8 04:47   13841 GOES18  
C6.7 05:18   13841 GOES18  
C6.2 05:42   13835 GOES18  
C5.8 06:00   13841 GOES18 simultaneous flare in AR 13842
C5.9 06:36   13841 GOES18  
C8.6 06:48 N10E73 13848 GOES16  
C5.9 07:36   13842 GOES16  
C5.2 07:41   13841 GOES16  
C5.5 07:54   13841 GOES16  
M1.5 08:28   13841 GOES16  
M1.5 08:36   13842 GOES16  
M1.1 09:22   13848 GOES16 simultaneous flare in AR 13841
M1.0 10:15 southeast limb S10191 GOES16  
C9.7 10:56   13842 GOES16 simultaneous flare in AR 13845
C9.9 11:13   13842 GOES16  
C9.7 11:46   13842 GOES16  
M1.1 12:03   13844 GOES16  
X9.0 12:18   13842 GOES16 full halo CME, weak type IV and moderate type II radio sweep, largest flare of SC25
M1.7 13:05   13844 GOES16  
M1.5 13:34   13848 GOES16  
M1.7 15:39   13844 GOES16  
M1.5 17:21 S16W26 13844 GOES16  
C9.6 18:47   S10191 GOES16  
M1.1 19:20   13844 GOES16 simultaneous flare at the southwest limb
M6.7/2B 20:28   13843 GOES16 moderate type II radio sweep
M2.3 21:41 S15W26 13844 GOES16  
C8.8 23:12   13842 GOES16  
M1.1 23:28   13842 GOES16  
C8.5 23:37   S10191 GOES16  

Coronal mass ejections (CMEs)

October 3: A full halo CME aimed nearly straight at Earth was observed after the X9 flare in AR 13842. The CME could arrive either late on October 4 or on October 5 and cause active to very severe geomagnetic storm levels.
October 2
: No obviously Earth directed CMEs observed.
October 1: A faint, full halo CME was observed after the X7.1 flare in AR 13842. The CME is likely to arrive on October 4 and cause unsettled to major geogmagnetic storm levels.

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 small positive polarity trans equatorial coronal hole (CH1245) will likely rotate into an Earth facing position on October 4-5.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be at quiet levels most of October 3. Late in the day or during the first half of October 4 the October 1 CME is likely to arrive and cause unsettled to severe storm levels.

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
13835 2024.09.22
2024.09.22
  1   S22W84 0002   AXX   location: S20W79
13836 2024.09.22
2024.09.23
5 8 4 S11W62 0010 BXO CRO

location: S13W61

area: 0020

13845 2024.09.23
2024.10.01
1 9 3 N17W74 0010 AXX CRO location: N17W68

area: 0025

SWPC position is way off

13838 2024.09.24
2024.09.26
      N15W54           location: N16W51
13840 2024.09.25
2024.09.27
      N14W70           location: N12W67
13841 2024.09.25
2024.09.28
25 52 27 N13W22 0200 DAI DAI  
13839 2024.09.26
2024.09.26
1 14 6 S14W22 0060 HSX CSO

area: 0090

location: S14W20

13842 2024.09.27
2024.09.28
35 63 38 S15W08 0530 EKC EKC beta-gamma-delta

area: 1250

location: S16W08

S10169 2024.09.27   8 1 S21W39 0020   AXX  
S10170 2024.09.27       N25W43            
S10171 2024.09.27   10 2 S04W15 0020   BXO  
S10172 2024.09.27       S03W44            
13843 2024.09.28
2024.09.29
19 24 16 S09W39 0250 EHI EKC

beta-gamma-delta

location: S09W42

area: 0440

S10176 2024.09.28       N17E14            
S10177 2024.09.28   2   N16W53 0003   AXX    
S10178 2024.09.28       S14W17            
13844 2024.09.29
2024.09.30
25 41 25 S15W30 0350 DKI EKC

beta-gamma-delta

area: 1030

S10180 2024.09.29       N01W07            
13846 2024.09.30
2024.10.01
2     S09W79 0020 CRO     location: S09W92

rotated out of view

SWPC location is way off

S10182 2024.09.30       S07E15            
13847 2024.09.30
2024.10.01
1 4 3 S28E31 0020 HRX CRO

location: S28E35

S10184 2024.09.30       N28W21            
13848 2024.10.01
2024.10.02
15 35 18 N13E56 0330 DKC DKC beta-gamma

area: 1510

S10186 2024.10.01   4 1 N17E11 0007   BXO  
S10187 2024.10.01       N34W30            
S10188 2024.10.01       S34W08            
S10189 2024.10.02   3 1 N10W09 0007   BXO  
S10190 2024.10.02   15 1 S17E09 0020   BXO  
S10191 2024.10.03   6 4 S06E78 0500   CKO    
S10192 2024.10.03   4 2 S10W00 0010   BXO    
S10193 2024.10.03   3   S22E35 0004   AXX    
S10194 2024.10.03   4   S12E47 0006   AXX    
Total spot count: 129 310 151  
Sunspot number: 229 510 311  (total spot count + 10 * number of spotted regions)
Weighted SN: 185 379 220  (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): 252 281 249  

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
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
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) 8.95
2023.07  176.4 182.2 160.0 124.6 (-0.7) 8.15
2023.08  153.7 157.6 114.8 124.3 (-0.3) 7.19
2023.09  154.4 156.0 134.2 124.0 (-0.3) 14.26
2023.10  142.8 141.9 99.4 124.8 (+0.8) 8.16
2023.11 153.5 150.2 105.4 127.8 (+3.0) 12.20
2023.12 151.1 146.4 114.2 129.4 (+1.6) 9.60
2024.01 164.6 159.3 126.0 131.1 (+1.7) 5.46
2024.02 172.5 168.3 123.0 136.8 (+5.7) 5.31
2024.03 154.4 152.9 103.7 141.3 (+4.5) 11.03
2024.04 161.3 162.6 136.5 (145.3 projected, +4.0) 9.69
2024.05 187.7 191.9 171.7 (151.6 projected, +6.3) 23.56
(SC25 peak)
2024.06 184.3 190.2 164.2 (155.5 projected, +3.9) 10.24
2024.07 196.6
 
203.0 196.5  (158.4 projected, +2.9) 7.13
2024.08  246.1
(cycle peak)
252.2 215.5  (SC25 peak) (160.4 projected, +2.0) 15.96
2024.09 195.7 197.8 141.4 (163.1 projected, +2.7) 15.3
2024.10 277.0 (1)   20.0 (2A) / 206.3 (2B) / 194.9 (2C) (165.4 projected, +2.3) (6.0)
2024.11       (163.7 projected, -1.7)  
2024.12       (160.7 projected, -3.0)  
2025.01       (156.3 projected, -4.4)  
2025.02       (149.6 projected, -6.7)  
2025.03       (144.8 projected, -4.8)  
2025.04       (141.6 projected, -3.2)  

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 September 7, 2024

Sunspot counts in August 2024 were much higher than during any previous solar cycle 25 month. In comparison only 3 months during solar cycle 23 had higher SSN. Sunspot counts in early September are still high, although lower than in the beginning of August. With at least 5 consecutive months of high sunspot counts the projected peak for the smoothed ISN (365 days smoothing) has increased significantly to above 160 and could easily surpass 170 if the current activity lasts through October. The month of the peak is likely to occur sometime between July and November 2024.

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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.