Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 8, 2023 at 08:10 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 8, 2023)
Solar cycle Solar cycles 23-25 (October 1, 2023) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (October 1, 2023) 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 (October 1, 2023) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (October 1, 2023) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (July 10, 2023) 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

Recent activity

The geomagnetic field was quiet on October 7. Solar wind speed at SOHO ranged between 310 and 453 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels.

Solar flux density measured at 20h UT on 2.8 GHz was 157.2 - decreasing 6.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 155.05. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.8). Three hour interval K indices: 11100021 (planetary), 12101112 (Boulder), 11010024 (Andenes).

The background x-ray flux is at the class C1 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 16 active regions using 2K resolution (SN: 292) and in 13 active regions using 1K resolution (SN: 203) SDO/HMI images.

Region 13448 [N13W86] decayed slowly and quietly.
Region 13450 [S22W53] lost the leader spots and was mostly quiet. C1 flares: C1.3 @ 02:32, C1.7 @ 14:45 UT
Region 13451 [N16W33] produced a few C flares and still has a weak magnetic delta in a central penumbra. C1 flares: C1.4 @ 04:41, C1.7 @ 20:47, C1.9 @ 20:57 UT
Region 13452 [N10W38] contributed with a few C flares and displayed no significant changes over the previous day. C1 flares: C1.5 @ 19:46 UT
Region 13454 [S11W13] developed slowly and was mostly quiet.
Region 13455 [N27W02] decayed slowly and quietly.
Region 13456 [S32W56] decayed slowly and quietly.
Region 13457 [S11E25] was quiet and stable.
Region 13458 [N15W23] was quiet and stable.
Region 13459 [N07E46] decayed slowly and quietly.
New region 13460 [S10E36] rotated into view with tiny spots on October 5. New flux emerged on October 7 and the region produced an M flare while only a few tiny and small spots were visible. C1 flares: C1.6 @ 22:28, C1.8 @ 23:01 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9026 [N11E53] developed slowly and quietly.
S9030 [N19W78] was quiet and stable.
S9032 [N21E73] was mostly quiet and stable. C1 flares: C1.7 @ 05:21 UT
New region S9036 [N30E17] was observed with tiny spots in an old plage area.
New region S9037 [S12W22] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.5 08:15   13451 GOES16  
C2.8 13:54   13451 GOES16  
M1.7 18:06 S10E39 13460 GOES16  
C3.3 18:30 N10W31 13452 GOES16  
C5.3 23:25 N10W36 13452 GOES16  

Coronal mass ejections (CMEs)

October 5-7: No obviously Earth directed CMEs were observed.

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 trans equatorial coronal hole (CH1178) will be Earth facing on October 8-10.

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

Forecast

The geomagnetic field is likely to be quiet on October 8-10. Effects from CH1178 could cause unsettled and active conditions on October 11-12.

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
13448 2023.09.24
2023.09.25
1 1   N13W87 0030 HSX HSX area: 0070
13450 2023.09.27
2023.09.27
1 4 2 S19W67 0010 AXX AXX location: S22W53

area: 0007

13451 2023.09.29
2023.09.30
22 31 23 N16W33 0180 EAI EAC beta-delta

area: 0350

13452 2023.09.29
2023.10.01
16 27 15 N11W36 0180 EAI EAO

location: N10W38

13454 2023.09.30
2023.10.01
8 16 9 S11W13 0030 CSO CAO

area: 0060

13453 2023.10.01
2023.10.01
      N10W72          
S9013 2023.10.01       N30W58            
13455 2023.10.01
2023.10.02
  4   N27W07 0010   AXX location: N27W02
S9016 2023.10.02       S25W52            
13456 2023.10.03   1   S31W62 0002   AXX

 

location: S32W57

13457 2023.10.03
2023.10.04
1 5 3 S11E24 0020 HRX CRO area: 0030

location: S11E25

S9020 2023.10.03       S34W13            
S9021 2023.10.03       S29W06            
S9022 2023.10.04       S13W28            
13458 2023.10.04
2023.10.05
1 3 2 N15W23 0010 AXX AXX  
13459 2023.10.05 3 8 3 N07E44 0020 CRO CRO area: 0035

location: N07E46

S9025 2023.10.05       S18W02            
S9026 2023.10.05   6 3 N11E53 0007   DRO  
S9027 2023.10.05       N20E12            
S9028 2023.10.05       N10E07            
13460 2023.10.05
2023.10.07
2 19 8 S11E35 0010 AXX CRI   beta-gamma

area: 0080

location: S10E36

S9030 2023.10.06   2 2 N19W78 0008   BXO  
S9031 2023.10.06       N02E62          
S9032 2023.10.06   1 1 N21E73 0015   HRX  
S9033 2023.10.06       S27W23          
S9034 2023.10.06       S31W34          
S9036 2023.10.07   3 1 N30E17 0007   AXX    
S9037 2023.10.07   1 1 S12W22 0002   AXX    
Total spot count: 55 132 73  
Sunspot number: 145 292 203  (total spot count + 10 * number of spotted regions)
Weighted SN: 81 167 103  (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): 160 161 162  

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
2022.03 117.0 115.8 78.6 68.7 (+4.0) 10.20
2022.04 130.8 131.7 84.0 73.0 (+4.3) 11.79
2022.05 133.8 136.8 96.5 77.4 (+4.4) 7.48
2022.06 116.1 119.8 70.3 81.1 (+3.7) 8.20
2022.07 125.4 129.5 91.4 86.7 (+5.6) 9.51
2022.08 114.2 117.1 74.6 92.6 (+5.9) 10.92
2022.09 135.1 136.5 96.0 96.5 (+3.9) 12.18
2022.10 133.5 132.7 95.5 98.9 (+2.4) 11.16
2022.11 123.4 120.7 80.5 101.1 (+2.2) 9.33
2022.12 147.9 143.4 112.8 106.7 (+5.6) 10.99
2023.01 182.4 176.6 144.4 113.4 (+6.7) 8.73
2023.02 167.2 163.2 111.3 117.9 (+3.5) 14.48
(current
SC25 peak)
2023.03 157.2 155.6 123.3 121.2 (+3.3) 14.42
2023.04 145.4 146.4 96.4 (126.6 projected, +5.4) 13.40
2023.05 155.6 159.2 137.9 (132.2 projected, +5.6) 10.67
2023.06 161.7 166.8 163.4 (135.4 projected, +3.2) 8.95
2023.07  176.4 182.2 159.1 (135.8 projected, +0.4) 8.15
2023.08  153.7 157.6 114.9 (137.6 projected, +1.8) 7.19
2023.09  154.4 156.0 133.6 (141.0 projected, +3.4) 14.26
2023.10  156.6 (1)   33.7 (2A) / 149.3 (2B) / 151.0 (2C) (142.8 projected, +1.8) (8.4)
2023.11       (145.4 projected max SC25, +2.6)  
2023.12       (144.5 projected, -0.9)  
2024.01       (141.7 projected, -2.8)  
2024.02       (141.5 projected, -0.2)  
2024.03       (141.0 projected, -0.5)  
2024.04       (138.2 projected, -2.8)  

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 August 20, 2023

Looking back 6 months, the 365d smoothed values for solar flux and all sunspot numbers with the exception of NOAA's, are all above their solar cycle 24 peak. The first peak of solar cycle 25 is forecast to be between July 7 and 10, 2023 (solar flux on July 7, ISN and STAR 1K and 2K all have that peak on July 9, while NOAA peaks on July 10). This is unlikely to be the final peak of SC25, however, there is a small probability that it is the actual sunspot and solar flux maximum.

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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.