Solar Terrestrial Activity Report

Activity chart

Last major update issued on October 13, 2023 at 06:10 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 very quiet on October 12. Solar wind speed at SOHO ranged between 321 and 365 km/sec. The high latitude magnetometer at Andenes recorded quiet levels. A low speed stream, probably associated with CH1178, began influencing the field early on October 13.

Solar flux density measured at 20h UT on 2.8 GHz was 157.1 - increasing 18.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 155.13. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.3). Three hour interval K indices: 10100001 (planetary), 10001311 (Boulder), 20000000 (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 15 active regions using 2K resolution (SN: 255) and in 11 active regions using 1K resolution (SN: 163) SDO/HMI images.

Region 13454 [S10W84] produced several low level C flares as it rotated to the southwest limb.
Region 13460 [S11W31] decayed slowly and quietly.
Region 13461 [N13W17] decayed slowly and quietly.
Region 13462 [N19E15] decayed slowly and quietly.
Region 13463 [S18E25] was mostly quiet and stable. C1 flares: C1.7 @ 16:07 UT
Region 13464 [N05E35] produced a few few C flares and did not change significantly. C1 flares: C1.4 @ 17:11 UT
Region 13465 [N10E57] was quiet and stable.
Region 13466 [N08W09] was mostly quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9050 [S13W24] was quiet and stable.
S9051 [S23W01] was quiet and stable.
New region S9052 [N25E29] emerged with a tiny spot before noon, then decayed slowly.
New region S9053 [N19E28] was observed with a tiny spots in an old plage area.
New region S9054 [S00E55] emerged with a tiny spot.
New region S9055 [S14W21] emerged with tiny spots.
New region S9056 [N18W05] emerged with tiny spots.

AR 13451 produced a C1.4 flare from behind the northwest limb at 19:15 UT

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C9.7 03:54   13460 GOES16 two flare centers
M1.1 04:58   13451 GOES18  
C2.8 06:00   13464 GOES16  
C2.2 06:47   13451 GOES16  
C2.0 07:44   13451 GOES16  
C2.4 08:43   13454 GOES16  
C2.3 08:57   13451 GOES16  
C2.0 09:41   13454 GOES16  
C2.1 10:51   13454 GOES16  
C2.2 11:54   13454 GOES16  
C2.5 12:11   13454 GOES16  
C2.7 12:20   13464 GOES16  
C3.0 12:32   13454 GOES16  
C2.7 13:15   13451 GOES16  
C2.4 13:34   13454 GOES16  
C3.0 14:37 behind northeast limb   GOES16 LDE
C2.6 15:09   13451 GOES16  
C2.3 17:52   13464 GOES16  
C2.3 21:05   13451 GOES16  

Coronal mass ejections (CMEs)

October 10-12: 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 negative polarity coronal hole (CH1178) was Earth facing on October 8-9. A small southern hemisphere positive polarity coronal hole (CH1179) will likely rotate across the central meridian on October 12-13.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet  to unsettled on October 13-14 due to weak coronal hole effects and quiet on October 15.

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
13454 2023.09.30
2023.10.01
1 1   S11W85 0040 HSX HRX  
13455 2023.10.01
2023.10.02
      N27W77         location: N26W64
13457 2023.10.03
2023.10.04
      S11W45           location: S13W40
13459 2023.10.05       N07W25            
S9025 2023.10.05       S18W67            
13461 2023.10.05
2023.10.08
2 6 3 N13W16 0010 BXO AXX  
S9027 2023.10.05       N20W53            
S9028 2023.10.05       N10W58            
13460 2023.10.05
2023.10.07
11 20 9 S11W31 0120 DAO ESO

area: 0260

S9031 2023.10.06       N02W03            
13462 2023.10.06
2023.10.08
8 13 8 N19E10 0050 CAO CRO location: N19E15
S9036 2023.10.07       N27W28          
13463 2023.10.08
2023.10.09
12 18 10 S17E20 0070 DAI DRI location: S18E25

area: 0110

13466 2023.10.08
2023.10.11
3 13 6 N09W09 0020 CAO CRO area: 0040
13464 2023.10.09
2023.10.10
6 15 8 N04E36 0090 CAO DAI

area: 0140

location: N05E35

13465 2023.10.10
2023.10.11
3 5 3 N10E56 0180 HSX CHO area: 0300
S9049 2023.10.10       S05W14          
S9050 2023.10.10   4   S13W14 0006   AXX  
S9051 2023.10.10   3 2 S23W01 0008   AXX  
S9052 2023.10.12   1   S25E29 0002   AXX    
S9053 2023.10.12   1 1 N19E28 0004   AXX    
S9054 2023.10.12   1   S00E55 0001   AXX    
S9055 2023.10.12   2 1 S14W21 0004   BXO   classification in picture
should have been BXO
S9056 2023.10.12   2 2 N18W05 0008   BXO    
Total spot count: 46 105 53  
Sunspot number: 126 255 163  (total spot count + 10 * number of spotted regions)
Weighted SN: 81 137 85  (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): 139 140 130  

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  158.2 (1)   55.4 (2A) / 143.2 (2B) / 150.0 (2C) (142.8 projected, +1.8) (6.6)
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.