Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 9, 2024 at 05:10 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 (October 6, 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 unsettled to severe storm levels on October 8 due to CME effects the first half of the day. After noon a high speed stream associated with CH1245 became the dominant solar wind source. Solar wind speed at SOHO ranged between 412 and 502 km/sec. The high latitude magnetometer at Andenes recorded unsettled to severe storm levels. The above 10 MeV proton flux was at background levels, however, proton flux levels are currently increasing after the X class flare in AR 13848 and could surpass event levels shortly.

Solar flux density measured at 20h UT on 2.8 GHz was 224.7 - increasing 17.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 178.88. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 178.88 on April 9, 2024). The Potsdam WDC planetary A index was 56 (STAR Ap - based on the mean of three hour interval ap indices: 56.1). Three hour interval K indices: 77643444 (planetary), 57644435 (Boulder), 67534546 (Andenes).

The background x-ray flux is at the class C2 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 352) and in 13 active regions using 1K resolution (SN: 235) SDO/HMI images.

AR 13842 [S15W77] lost area and the magnetic delta in the large leading penumbra disappeared.
AR 13847 [S29W23] decayed slowly and quietly.
AR 13848 [N12W10] has a small magnetic delta near the southern edge of the largest penumbra. Several C flares were recorded during the day. The region produced an X1.8 long duration proton event peaking at 01:55 UT. A fast full halo CME was observed in LASCO imagery shortly afterwards.
AR 13849 [S07E14] developed further and has a small magnetic delta configuration. A major flare is possible. The region was the source of the largest flare of the day, an M1.8 event at 01:04 UT
AR 13850 [S10E09] decayed slowly and quietly.
AR 13851 [S11W25] decayed slowly and quietly.
AR 13852 [S11E56] was mostly unchanged and remains capable of producing a minor M class flare.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S10190 [S14W60] developed as new flux emerged.
S10200 [S15W03] was quiet and stable.
New region S10209 [N19E59] emerged with several spots.
New region S10211 [N11W74] emerged with several spots.
New region S10212 [N29E22] emerged with tiny spots.
New region S10213 [S10E75] emerged with a tiny spot.
New region S10214 [S06E62] emerged with a tiny spot.
New region S10215 [N13E20] emerged with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
M1.8 01:04   13849 GOES16  
M1.2 01:46   13842 GOES16  
C6.8 03:53 behind southwest limb   GOES16  
C6.4 04:03   13842 GOES16  
C7.8 06:12 filament eruption SW quadrant   GOES16 LDE
C8.3 06:18 behind southwest limb   GOES16  
C7.7 06:54   13842 GOES16  
C7.5 07:42   13842 GOES16  
C7.4 08:20   13849 GOES16 simultaneous flare in AR 13848
M1.2 08:51 S12W65 13842 GOES16  
C4.8 11:05   13842 GOES16  
C5.4 11:53   13844 GOES16  
C3.9 13:03   13849 GOES16  
C3.7 13:39 behind southwest limb   GOES16 simultaneous flare in AR 13851
C3.8 17:20   13842 GOES16  
C5.8 17:50   13844 GOES16  
C4.1 19:08   13844 GOES16  
C8.0/1N 20:29   13849 GOES16  
C6.6 20:38   13842 GOES16  
C3.3 23:21   13850 GOES16  
C3.1 23:36 behind southwest limb   GOES16  
C3.9 00:04 behind southwest limb 13844 GOES16  

Coronal mass ejections (CMEs)

October 6: No obviously Earth directed CMEs observed.
October 7: A full halo CME was observed after the M7 and X1 LDEs in AR 13844. While Earth is not in the path of the CME core, there is a chance of a solar wind shock on October 11.
October 8: A partiual halo CME was observed from 05:12 UT in LASCO imagery after a large filament eruption in the southwest quadrant. This CME could reach Earth on October 11.
October 9: A full halo CME was observed after the X1 flare in AR 13848 early in the day. This CME will likely overtake the previously mentioned CMEs and arrive after noon on October 10.

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]

An extension of the northern polar coronal hole will rotate across the central meridian on October 9-10. The extension is probably too far to the north to cause a disturbance.

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

Forecast

The geomagnetic field is expected to be at quiet to active levels on October 9 due to effects from CH1245. Mostly quiet conditions are likely the first half of October 10. The October 9 CME could reach Earth on October 10 and cause unsettled to very severe storm conditions that day and on October 11.

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
13841 2024.09.25
2024.09.28
3     N14W91 0010 BXO    

spotless at noon

13839 2024.09.26
2024.09.26
1     S14W91 0020 HSX     rotated out of view
13842 2024.09.27
2024.09.28
9 22 12 S13W76 0630 EKI EKI beta-gamma

location: S15W77

S10176 2024.09.28       N17W51            
13844 2024.09.29
2024.09.30
4     S15W96 0300 DKO    

rotated out of view

SWPC spot count copy of previous day, there was not more than one spot visible on Oct.8.

13847 2024.09.30
2024.10.01
  5 1 S27W38 0010   BXO

location: S29W23

13848 2024.10.01
2024.10.02
14 44 21 N12W11 0600 DKI DKC beta-gamma-delta

area: 1020

location: N12W10

S10186 2024.10.01       N17W54            
S10190 2024.10.02   7 3 S14W60 0040   CRO  
13849 2024.10.03
2024.10.04
24 54 31 S07E13 0310 DKI DKC beta-gamma-delta

location: S07E14

area: 0650

S10193 2024.10.03       S22W29            
13851 2024.10.03
2024.10.07
1 2   S08W27 0010 AXX AXX location: S11W25

area: 0003

S10196 2024.10.05       N13E04            
S10198 2024.10.05       N13W28            
S10200 2024.10.05   5 1 S15W03 0015   AXX  
13850 2024.10.06
2024.10.06
11 21 12 S10E08 0150 CAO CAI

location: S10E09

area: 0230

S10203 2024.10.06       S42E19            
13852 2024.10.06 8 25 14 S14E54 0350 DKO EKO location: S11E56

area: 0550

S10205 2024.10.06
2024.10.07
      N15W51            
S10206 2024.10.06       N16W04          
S10208 2024.10.07       S09W39          
S10209 2024.10.08   7 5 N19E59 0020   CRO    
S10211 2024.10.08   4 2 N11W74 0010   BXO    
S10212 2024.10.08   3 1 N29E22 0008   BXO    
S10213 2024.10.08   1 1 S10E75 0002   AXX    
S10214 2024.10.08   1   S06E62 0002   AXX    
S10215 2024.10.08   1 1 N13E20 0003   AXX    
Total spot count: 75 202 105  
Sunspot number: 165 352 235  (total spot count + 10 * number of spotted regions)
Weighted SN: 135 253 156  (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): 182 194 188  

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) 15.36
2024.10 266.5 (1)   47.4 (2A) / 183.6 (2B) / 196.4 (2C) (165.4 projected, +2.3) (15.5)
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 October 6, 2024

September 2024 saw a significant decrease in sunspot numbers compared to the previous month, however, activity was still fairly high. The average solar flux for the month ranks as number 3 of all months during SC25. Taking into account that we started seeing high sunspot numbers April 14, 2024, the most likely candidate for solar maximum would be at or just after October 14, 2024. Assuming that the average sunspot number from now until April 14, 2025 becomes 150, we would be looking at a 365 days smoothed sunspot maximum of 164.5 centered on October 14. Should the average sunspot number for that period become 160 we would get a peak near 169.7.

--------------------------------------------------------------------------------------

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.