Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 11, 2023 at 06:55 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 (December 7, 2023)
Solar cycle Solar cycles 23-25 (December 1, 2023) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (December 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 (December 1, 2023) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (December 1, 2023) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (November 26, 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 December 10. Solar wind speed at SOHO ranged between 338 and 390 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled levels.

Solar flux density measured at 20h UT on 2.8 GHz was 126.6 - decreasing 6.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 158.18. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 158.42 on June 4, 2023). The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4). Three hour interval K indices: 11100121 (planetary), ******** (Boulder), 10100232 (Andenes).

The background x-ray flux is at the class B6 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 233) and in 13 active regions using 1K resolution (SN: 186) SDO/HMI images.

Region 13507 [N07W80] was quiet and stable.
Region 13508 [S16W80] was quiet and stable.
Region 13510 [S14W77] decayed slowly and quietly.
Region 13511 [S22W76] was unstable despite significant decay in most parts of the region. C1 flares: C1.9 @ 03:03, C1.4 @ 05:17, C1.1 @ 05:55, C1.8 @ 07:54, C1.0 @ 16:30, C1.1 @ 17:28, C1.2 @ 18:39, C1.3 @ 19:15, C1.9 @ 21:49, C1.3 @ 22:24 UT
Region 13513 [N18W02] decayed and was mostly quiet. C1 flares: C1.3 @ 06:11 UT
Region 13514 [N07E02] decayed further and was quiet.
Region 13515 [S14E49] decayed slowly and quietly.
Region 13516 [S18E50] was quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9214 [S18W58] was quiet and stable.
S9220 [N14E11] reemerged with tiny spots.
S9222 [N18E26] reemerged with tiny spots.
New region S9227 [N06W36] was observed with a tiny spot in an old plage region.
New region S9228 [N15W23] emerged with a tiny spot.
New region S9229 [N25W33] was observed with a tiny spot in an old plage area.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.0 02:06   13511 GOES18  
M2.3 03:53 S20W66 13511 GOES18  
C4.3 04:47   13511 GOES18  
C7.0 07:16 S20W69 13511 GOES18  
C2.1 08:19   13511 GOES18  
C6.6 10:42   13511 GOES18  
C5.5 11:55   13511 GOES18  
C3.9 14:28   13511 GOES18  
C2.1 14:46   13513 GOES18  
C7.3 20:47   13511 GOES18  
C2.7 21:12   13511 GOES18  
C5.5 22:33   13511 GOES18  
M1.4 22:43   13511 GOES18  

Coronal mass ejections (CMEs)

December 8-10: 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 southern hemisphere positive polarity coronal hole (CH1191) was Earth facing on December 7. An extensive trans equatorial positive polarity coronal hole (CH1192) will likely rotate across the central meridian on December 11-13.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet to unsettled on December 11 due to weak effects from CH1191. Quiet conditions are likely on December 12-13. Quiet to minor storm is possible on December 14-16 due to effects from CH1192.

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
13508 2023.11.28
2023.11.29
1 1 1 S16W82 0030 HAX HSX area: 0080

location: S16W80

13507 2023.11.28
2023.11.29
1 1 1 N07W80 0070 HSX HSX

area: 0200

13510 2023.12.02
2023.12.03
3 2 1 S15W75 0010 AXX AXX area: 0007

location: S14W77

13512 2023.12.03
2023.12.04
      S09W24          

location: S08W21

13511 2023.12.03
2023.12.03
9 8 6 S23W71 0140 FSI FAO

location: S22W76

area: 0220

S9210 2023.12.04       S25W30          
13513 2023.12.04
2023.12.05
16 34 22 N19W01 0220 EAI EAI beta-gamma

location: N18W02

area: 0300

13514 2023.12.05
2023.12.06
6 5 2 N10E07 0030 CSO HRX

location: N07E02

S9214 2023.12.05   3 1 S18W58 0010   BXO  
S9216 2023.12.06       N28W34            
13516 2023.12.08
2023.12.08
3 7 4 S18E52 0040 CSO CSO

area: 0120

location: S18E50

13515 2023.12.08
2023.12.08
1 2 1 S15E48 0010 AXX HRX

area: 0030

location: N14E49

S9220 2023.12.08   18 11 N14E11 0050   CRI   split off from AR 13514
S9222 2023.12.08   8 4 N17E23 0013   BXO    
S9223 2023.12.08       S11W35            
S9224 2023.12.08       S00E01            
S9225 2023.12.09       N05E02          
S9226 2023.12.09       N18W26          
S9227 2023.12.10   2 1 N06W36 0005   BXO    
S9228 2023.12.10   1   S15W23 0004   AXX    
S9229 2023.12.10   1 1 N25W33 0003   AXX    
Total spot count: 40 93 56  
Sunspot number: 120 233 186  (total spot count + 10 * number of spotted regions)
Weighted SN: 70 127 90  (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): 132 128 149  

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
2022.04 130.8 131.7 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 80.5 101.2 (+2.3) 9.33
2022.12 147.9 143.4 112.8 106.7 (+5.5) 10.99
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
(current
SC25 peak)
2023.03 157.2 155.6 123.3 121.0 (+3.2) 14.42
2023.04 145.4 146.4 97.6 122.7 (+1.7) 13.40
2023.05 155.6 159.2 137.4 123.9 (+1.2) 10.67
2023.06 161.7 166.8 160.5 (126.3 projected, +2.4) 8.95
2023.07  176.4 182.2 159.1 (127.1 projected, +0.8) 8.15
2023.08  153.7 157.6 114.8 (128.2 projected, +1.1) 7.19
2023.09  154.4 156.0 133.6 (130.4 projected, +2.2) 14.26
2023.10  142.8 141.9 99.4 (132.2 projected, +1.8) 8.16
2023.11 153.5 150.2 105.4 (134.1 projected max SC25, +1.9) 12.20
2023.12 138.0 (1)   38.8 (2A) / 120.2 (2B) / 132.0 (2C) (132.7 projected, -1.4) (12.3)
2024.01       (130.0 projected, -2.7)  
2024.02       (129.9 projected, -0.1)  
2024.03       (129.3 projected, -0.6)  
2024.04       (130.1 projected, +0.8)  
2024.05       (132.2 projected, +2.1)  
2024.06       (131.5 projected, -0.7)  

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 December 7, 2023

Due to relatively low solar activity over the last couple of months, the possibility that solar cycle 25 has already peaked has increased significantly. Whether the first peak (and maybe solar max) will be in June or July depends on solar activity in December and early January 2024. If the average solar flux is less than 150 during this period, the first peak of solar cycle 25 using 365 day smoothing will likely be sometime between June 2 and July 9. Should the average solar flux instead become 140 then the peak date will be in early June (June 4 for solar flux, June 6 for STAR 2K SN, and June 7 for all the other sunspot numbers in the graph above). We won't know for a while yet when the final peak will be, however, it is interesting that the peak of SC25 could be as early as June 2023. The next update will likely be posted here in January 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.