Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 1, 2023 at 08:25 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 (November 5, 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 November 30. Solar wind speed at SOHO ranged between 336 and 497 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled levels. A moderate solar wind shock was recorded at SOHO at 23:39 UT and a geomagnetic disturbance started early December 1. This was likely the arrival of one of the November 27 CMEs.

Solar flux density measured at 20h UT on 2.8 GHz was 166.5 - increasing 10.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 158.23. 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: 4.3). Three hour interval K indices: 22111010 (planetary), 21213221 (Boulder), 33000020 (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: 270) and in 15 active regions using 1K resolution (SN: 212) SDO/HMI images.

Region 13492 [N19W70] decayed slowly and quietly.
Region 13493 [S12W62] decayed slowly and was mostly quiet. C1 flares: C1.4 @ 03:40, C1.8 @ 04:20, C1.4 @ 18:07 UT
Region 13494 [S17W54] decayed slowly and quietly.
Region 13500 [S18W29] became more complex again as new magnetic delta structures formed. Another major flare is possible. C1 flares: C1.4 @ 02:08 UT
Region 13501 [S08W21] was quiet and stable.
Region 13502 [N14W67] developed slowly and quietly. The region produced an M1.1 flare at 04:39 UT on December 1. C1 flares: C1.6 @ 11:07 UT
Region 13503 [N21W06] decayed slowly and quietly.
Region 13505 [S17E42] was quiet and stable.
Region 13506 [N15W34] decayed slowly and quietly.
Region 13507 [N08E55] was quiet and stable.
Region 13508 [S15E66] was quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9156 [N21W83] developed after noon and could produce C flares while rotating over the northwest limb. C1 flares: C1.3 @ 00:45, C1.5 @ 01:52 UT
New region S9188 [N09W33] emerged with tiny spots.
New region S9189 [N28W00] emerged with tiny spots.
New region S9190 [S10W24] emerged with tiny spots.
New region S9191 [S13W33] emerged with tiny spots.

AR 13499 at the southwest limb produced a C1.3 flare at 01:31 UT

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.5 07:26   13502 GOES18  
C2.1 15:44   13500 GOES18  
C2.2 19:27   13500 GOES18  
C2.9 20:11   13502 GOES16 LDE
C2.4 22:31   13499 GOES18  
C3.6 22:48   13499 GOES18  

Coronal mass ejections (CMEs)

November 27: Several CMEs were observed during the day. The first one involved a filament eruption beginning just before 05h UT in SDO/AIA imagery. The eruption in the southwestern quadrant extended from close to the central meridian at its southernmost point to near the equator in the northwestern part of the filament channel. Coronal dimming was observed. A partial halo CME was observed and could reach Earth early on November 30. The second filament eruption began near 18:17 UT and occurred in the northeastern quadrant. The eruption affected areas as far south as AR 13500 and resulted in at least a partial halo CME, maybe a faint full halo CME. This CME is likely to reach Earth on December 1. The third filament eruption also occurred in the northeastern quadrant and further east than the previous eruption. This event began near 23:07 UT in SDO/AIA imagery. A partial halo CME was observed after this event and could influence Earth on December 1.
November 28: An asymmetrical full halo CME was observed after the M3.4 flare in AR 13500 at 19:32 UT. Another and brighter symmetrical full halo CME was observed after the major M9.8 flare at 19:50 UT. The CMEs are expected to merge. The combined CME is likely directed straight at Earth.
November 29-30: 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 well defined large recurrent negative polarity trans equatorial coronal hole (CH1190) will rotate across the central meridian on December 1-3.

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.

Forecast

The geomagnetic field is expected to be unsettled to severe storm on December 1-2 due to CME effects. Effects from CH1190 could cause unsettled to major storm conditions on December 3-5 and quiet tot active on December 6.

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
S9156 2023.11.18   2 2 N21W83 0100   DAO  
13490 2023.11.18       N22W84            
13492 2023.11.18
2023.11.20
3 2 2 N20W75 0060 CSO HSX

area: 0190

location: N19W70

13491 2023.11.18
2023.11.19
      N11W80           location: N10W73
13493 2023.11.20
2023.11.20
1 7 3 S13W61 0010 HRX BXO

location: S13W62

13494 2023.11.20
2023.11.20
1 2 1 S17W56 0030 HSX HSX

area: 0090

location: S17W54

13495 2023.11.20       N25W80            
13500 2023.11.22
2023.11.23
24 51 31 S18W30 0300 EKC EAC beta-gamma-delta

location: S18W29

area: 0530

13499 2023.11.22
2023.11.23
      S17W87            
13501 2023.11.22
2023.11.23
1 7 4 S09W21 0040 HSX CSO area: 0100

location: S08W21

13502 2023.11.22
2023.11.23
4 10 6 N15W68 0050 CSO DAO area: 0110

location: N14W67

S9173 2023.11.22       N13W46          
13503 2023.11.23
2023.11.25
1 6 4 N21W06 0000 AXX CRO

area: 0015

13506 2023.11.26
2023.11.29
  5   N15W43 0007   BXO

location: N15W34

S9180 2023.11.26       N38W55            
13505 2023.11.27
2023.11.28
1 3 1 S18E41 0020 HSX HSX area: 0080

location: S17E42

13508 2023.11.28
2023.11.29
1 1 1 S15E53 0040 HSX HSX area: 0200

location: S14E52

13507 2023.11.28
2023.11.29
1 2 1 N08E55 0070 HSX HHX area: 0330
S9186 2023.11.28       S09E01            
S9187 2023.11.28       S27W50            
S9188 2023.11.30   4 2 N09W33 0010   BXO    
S9189 2023.11.30   3 1 N28W00 0005   BXO    
S9190 2023.11.30   2 1 S10W24 0004   BXO    
S9191 2023.11.30   3 2 S13W33 0006   BXO  

 

Total spot count: 38 110 62  
Sunspot number: 138 270 212  (total spot count + 10 * number of spotted regions)
Weighted SN: 86 163 114  (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): 152 149 170  

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) 12.3
2023.12 (1)   (2A/2B) / 125.4 (2C) (132.7 projected, -1.4) ()
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 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.