Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 11, 2024 at 06:10 UT. Revised on January 31, 2025 based on archived SDO/HMI images

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 9, 2024)
Solar cycle Solar cycles 23-25 (December 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (December 1, 2024) Noon SDO sunspot count 1K image / 4K (*)
  Solar cycles 1-24 (August 1, 2020) POES auroral activity level [October 2009 - December 2012]
  Comparison of cycles 21-25 (December 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (December 1, 2024) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (October 13, 2024) 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
Calculating the Strength of Solar Cycle 25 Using 365-day Smoothing

Recent activity

The geomagnetic field was at quiet levels on December 10, weakly under the influence of a high speed stream from CH1259. Solar wind speed at SOHO ranged between 374 and 492 km/sec, averaging 423 km/sec (-47 compared to the previous day). The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at background levels all day.

Solar flux density measured at 20h UT on 2.8 GHz was 171.9 - increasing 25.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 187.96. In comparison SC24 peaked on June 28, 2014 at 145.50 while SC23 peaked on February 23, 2002 at 198.15. Current SC25 peak: 187.96 on June 11, 2024 (given a base solar flux level of 65, this is +52.75% compared to SC24 peak and -7.65% compared to SC23 peak). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.5). Three hour interval K indices: 22221112 (planetary), 22232211 (Boulder), 43321225 (Andenes).

At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 306) and in 10 active regions using 1K resolution (SN: 185) SDO/HMI images.

AR 13916 [S15W25] decayed slowly and quietly.
AR 13917 [S07W14] produced a few C flares and decayed slowly.
AR 13920 [N21E24] developed gaining spots and area, however, flare activity was low.
AR 13921 [S05W00] decayed slowly and quietly.
New AR 13922 [S17E62] rotated into view on December 9 and was numbered the next day by SWPC.
New AR 13923 [N23W27] emerged with small spots.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S10436 [S12E08] was quiet and stable.
S10441 [N31W19] reemerged with a tiny spot.
S10442 [S08E27] was quiet and stable.
S10444 [N17E13] was quiet and stable.
S10446 [N21W08] reemerged with tiny spots.
S10448 [S16W70] decayed slowly and quietly.
S10455 [N06E30] developed slowly and quietly.
New region S10458 [N08W42] was observed with tiny spots in an old plage area.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.6 03:02   13922 GOES16  
C9.7 03:27   13922 GOES16  
C3.0 05:15   13922 GOES16  
C2.7 06:07   13912 GOES16  
C3.3 06:16   13922 GOES16  
C5.3 06:31   13922 GOES16  
M6.4 06:48   13922 GOES16  
M3.7 06:52     GOES16  
M1.4 07:09   13922 GOES16  
C5.3 07:26     GOES16  
C2.0 09:53   13912 GOES16  
C2.1 10:49   13912 GOES16  
M1.5 11:02   13922 GOES16  
C2.6 12:17   13912 GOES16  
C2.7 12:22     GOES16  
C3.0 13:19     GOES16  
C3.4 13:25     GOES16  
C2.1 13:29     GOES16  
C2.6 13:42   13920 GOES16  
C2.2 14:38     GOES16  
C2.8 14:43   13920 GOES16  
C2.5 15:12   13917 GOES16  
C5.9 15:33   13912 GOES16  
C2.4 15:50     GOES16  
C4.9 16:20   13917 GOES16  
C2.1 17:12   13920 GOES16  
C2.2 17:22   13920 GOES16  
C2.1 17:39   13920 GOES16  
C3.3 17:49     GOES16  
M1.6 17:58   13922 GOES16  
C2.2 18:40     GOES16  
C3.0 19:18 S08W07 13922 GOES16  
C2.2 19:43   13920 GOES16  
C2.2 19:54   13912 GOES16  
C2.4 20:03     GOES16  
C3.3 20:10     GOES16  
C5.8 20:53   13912 GOES16  
C2.1 21:41   13922 GOES16  
C8.3 22:21   13912 GOES16  
C3.5 22:58   13920 GOES16  

C1 flares: C1.3 @ 00:45, C1.6 @ 00:58, C1.9 @ 01:03, C1.7 @ 01:48, C1.8 @ 02:02, C1.8 @ 02:11, C1.4 @ 02:50, C1.7 @ 03:54, C1.8 @ 05:38, C1.5 @ 08:11, C1.4 @ 09:42, C1.7 @ 10:31, C1.6 @ 11:38, C1.3 @ 12:54, C1.6 @ 14:09, C1.5 @ 14:23, C1.6 @ 16:39, C1.5 @ 17:01, C1.9 @ 17:17, C1.9 @ 21:57, C1.9 @ 23:26 UT

Coronal mass ejections (CMEs)

December 8-9: No obviously Earth directed CMEs were observed.
December 10: A partial halo CME was associated with a major M6.4 flare in AR 13922. Weak effects from this CME are possible on December 13-14.

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 positive polarity northern hemisphere coronal hole (CH1261) rotated across the central meridian on December 8-9, and may be too far to the north to cause a geomagnetic disturbance. A recurrent positive polarity northern hemisphere coronal hole (CH1262) will be in an Earth facing position on December 11.

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 expected to be quiet  on December 11 and quiet to unsettled on December 12-13 due to effects from CH1261. The December 10 CME could cause som unsettled and active intervals on December 13-14.

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
STAR/
SDO
SWPC STAR Current Previous
2K 1K
13912 2024.11.28 5     S06W91 0180 DAI       SWPC moved this AR to the location of AR S10418 on 2024.12.01
STAR data is for the original spot group

rotated out of view on December 9

S10418 2024.11.28       S07W88          

see AR 13912

13915 2024.12.02       N12W44            
13916 2024.12.02
2024.12.03
10 17 6 S15W28 0040 CRI DRO     was AR S10427

location: S15W25

13917 2024.12.03
2024.12.04
20 53 29 S08W16 0230 EAC DSC     beta-gamma

was AR S10432

location: S07W14

area: 0480

S10433 2024.12.04       S11W45            
S10436 2024.12.04   4   S12E08 0005   AXX      
S10438 2024.12.05       N15E13            
S10440 2024.12.05       N22W49            
S10441 2024.12.06   1   N31W19 0002   AXX      
S10442 2024.12.06   5   S08E27 0008   BXO      
13920 2024.12.06
2024.12.08
12 52 30 N22E24 0060 DSO EAC     was AR S10443

location: N21E24

area: 0360

S10444 2024.12.06   4 1 N17E13 0007   BXO      
S10445 2024.12.06       N09W40            
S10446 2024.12.06   1 1 N21W08 0003   AXX      
13919 2024.12.06
2024.12.08
      S14W20           was AR S10447

location: S14W17

S10448 2024.12.07   4 2 S16W70 0015   CRO      
13921 2024.12.07
2024.12.09
1 3 1 S07W01 0010 HRX CRO     was AR S10449
S10450 2024.12.07       N07W20            
S10451 2024.12.07       S08W29            
S10452 2024.12.08       S09W02            
S10453 2024.12.08       N00E36            
S10454 2024.12.08       S18W17            
S10455 2024.12.09   4 3 N06E30 0015   CRO      
S10456 2024.12.09       N37E01            
13922 2024.12.09
2024.12.10
4 11 8 S17E59 0020 CRO DRI     was AR S10457

area: 0060

location: S17E62

13923 2024.12.10
2024.12.10
3 5 4 N24W30 0020 CRO DRI     was AR S10457

area: 0060

location: N23W27

S10458 2024.12.10   2   N08W42 0004   AXX      
Total spot count: 55 166 85  
Sunspot number: 125 306 185  (total spot count + 10 * number of spotted regions)
Weighted SN: 79 194 113  (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): 138 168 148  

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
2023.04 145.4 146.4 97.6 122.9 (+1.8) 13.40
2023.05 155.6 159.2 137.4 124.2 (+1.3) 10.67
2023.06 161.7 166.8 160.5 125.3 (+1.1) 8.95
2023.07  176.4 182.2 160.0 124.6 (-0.7) 8.15
2023.08  153.7 157.6 114.8 124.3 (-0.3) 7.19
2023.09  154.4 156.0 134.2 124.0 (-0.3) 14.26
2023.10  142.8 141.9 99.4 124.8 (+0.8) 8.16
2023.11 153.5 150.2 105.4 127.9 (+3.1) 12.20
2023.12 151.1 146.4 114.2 129.5 (+1.6) 9.60
2024.01 164.6 159.3 126.0 131.1 (+1.6) 5.46
2024.02 172.5 168.3 123.0 136.9 (+5.8) 5.31
2024.03 154.4 152.9 103.7 141.4 (+4.5) 11.03
2024.04 161.3 162.6 137.0 144.4 (+3.1) 9.69
2024.05 187.7 191.9 172.1 149.1 (+4.7) 23.56
(SC25 peak)
2024.06 184.3 190.2 164.1 (152.1 projected, +3.0) 10.24
2024.07 196.6 203.0 196.5  (154.4 projected, +2.3) 7.13
2024.08  246.1
(cycle peak)
252.2 215.5  (SC25 peak) (156.2 projected, +1.8) 15.96
2024.09 195.7 197.8 141.4 (158.6 projected, +2.4) 15.36
2024.10 221.0 219.6 166.3 (160.7 projected, +2.1) 18.99
2024.11 198.3 195.3 152.5 (159.9 projected, -0.8) 9.33
2024.12 177.7 (1)   33.7 (2A) / 104.4 (2B) / - (2C) (157.8 projected, -2.1) (7.2)
2025.01       (153.4 projected, -4.4)  
2025.02       (146.6 projected, -6.8)  
2025.03       (141.8 projected, -4.8)  
2025.04       (138.9 projected, -2.9)  
2025.05       (134.9 projected, -4.0)  

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 10, 2024

Sunspot activity in November 2024 decreased compared to October and there is a trend towards lower levels since August 2024. The average solar flux for November was the fourth highest for a month during SC24. The above plot displays a projected peak for the ISN 365d smoothed sunspot numbers in October 15, 2024. All the other smoothed sunspot number have projected peaks either in late November or early December. Assuming that the average sunspot numbers in December 24 decreases significantly over the previous months, and then slowly until mid 2025, an earlier peak peak near July 9, 2024 becomes possible. Currently SC25 is tracking much closer to SC23 than to SC24.

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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.