Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 6, 2023 at 06:20 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 3, 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 to minor storm on October 5 under the influence of effects from CH1177 most of the day. Solar wind speed at SOHO ranged between 409 and 520 km/sec. A solar wind shock was observed at SOHO at 21:33 UT, the likely arrival of the October 2 CME. The high latitude magnetometer at Andenes recorded quiet to major storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 156.1 - decreasing 4.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 155.06. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 15.6). Three hour interval K indices: 45232112 (planetary), 35333123 (Boulder), 56233124 (Andenes).

The background x-ray flux is at the class B8 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 17 active regions using 2K resolution (SN: 306) and in 12 active regions using 1K resolution (SN: 197) SDO/HMI images.

Region 13448 [N13W60] was quiet and stable.
Region 13450 [S19W36] decayed further losing all mature penumbra.
Region 13451 [N17W05] developed as new flux emerged in the central parts. Several C flares were recorded. The region has polarity intermixing and an M class flare is possible. C1 flares: C1.3 @ 13:28, C1.2 @ 14:13, C1.6 @ 15:32, C1.5 @ 17:54 UT
Region 13452 [N09W11] decayed slowly losing spots. The region has weak polarity intermixing and may be capable of M class flaring. C1 flares: C1.3 @ 12:31 UT
Region 13453 [N10W44] decayed slowly and quietly.
Region 13454 [S12E11] decayed slowly and quietly.
Region 13455 [N27E24] was quiet and stable.
Region 13456 [S32W36] decayed slowly and quietly.
Region 13457 [S11E51] was mostly quiet and stable. C1 flares: C1.0 @ 09:19 UT
New region 13458 [N14E06] was numbered by SWPC as new flux emerged.
New region 13459 [N08E73] rotated into view with tiny spots.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9022 [S13W02] was quiet and stable.
New region S9025 [S18E24] emerged with tiny spots.
New region S9026 [N11E80] rotated into view with a tiny spot.
New region S9027 [N20E38] was observed with a tiny spot in an old plage area.
New region S9028 [N10E33] was observed with tiny spots in an old plage area.
New region S9029 [S11E70] rotated into view with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.7 07:00   13451 GOES16  
C3.5 16:30 N17W01 13451 GOES16  
C4.7 19:13 N18W02 13451 GOES16  
C4.0 21:15 S08E51 13457 GOES16 simultaneous flare in AR 13451
C2.1 22:07 N17W05 13451 GOES16  
C2.4 23:55   13451 GOES16  

Coronal mass ejections (CMEs)

October 3-5: 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 likely become Earth facing on October 9-10.

Propagation

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

Forecast

The geomagnetic field is likely to be quiet to minor storm on October 6 due to CME effects. Quiet conditions are likely on October 7-8.

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 4 1 N13W60 0050 HSX HSX area: 0110
S8994 2023.09.25       S21W53            
13449 2023.09.26       N15W82            
13450 2023.09.27
2023.09.27
13 18 13 S18W38 0090 EAO CRI location: S19W36

area: 0050

13451 2023.09.29
2023.09.30
18 33 20 N17W07 0140 DAI EAI beta-gamma

area: 0240

location: N17W05

13452 2023.09.29
2023.10.01
28 25 18 N11W08 0220 EAI EAI beta-gamma

location: N09W11

S9005 2023.09.30       N24W42            
13454 2023.09.30
2023.10.01
4 8 2 S14E11 0010 BXO HRX location: S12E11
13453 2023.10.01
2023.10.01
4 11 6 N11W44 0010 BXO CRO

location: N10W44

S9013 2023.10.01       N30W32            
13455 2023.10.01
2023.10.02
  6 3 N25E19 0012   AXX location: N27E24
S9016 2023.10.02       S25W26            
13456 2023.10.03 1 2 1 S31W34 0010 AXX HRX

location: S32W36

13457 2023.10.03
2023.10.04
1 4 2 S10E47 0030 HRX CRO area: 0020

location: S11E51

S9020 2023.10.03       S34E13            
S9021 2023.10.03       S29E19            
S9022 2023.10.04   2   S13W02 0008   BXO  
13458 2023.10.04
2023.10.05
7 11 6 N15E03 0010 BXO BXO location: N14E06
13459 2023.10.05 2 5 3 N10E65 0010 AXX CRO   was AR S9024
S9025 2023.10.05   2 2 S18E24 0006   BXO    
S9026 2023.10.05   1   N11E80 0002   AXX    
S9027 2023.10.05   1   N20E38 0003   AXX    
S9028 2023.10.05   2   N10E33 0003   BXO    
S9029 2023.10.05   1   S11E70 0001   AXX    
Total spot count: 79 136 77  
Sunspot number: 179 306 197  (total spot count + 10 * number of spotted regions)
Weighted SN: 102 169 110  (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): 197 168 158  

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  156.7 (1)   24.6 (2A) / 152.4 (2B) / 148.6 (2C) (142.8 projected, +1.8) (9.5)
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.