Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 14, 2024 at 07:30 UT. Revised on February 3, 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 very quiet levels on December 13. Solar wind speed at SOHO ranged between 307 and 368 km/sec, averaging 322 km/sec (-43 compared to the previous day). The high latitude magnetometer at Andenes recorded quiet to unsettled 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 163.7 - increasing 23.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 188.16. In comparison SC24 peaked on June 28, 2014 at 145.50 while SC23 peaked on February 23, 2002 at 198.15. Current SC25 peak: 188.16 on June 14, 2024 (given a base solar flux level of 65, this is +53.00% compared to SC24 peak and -7.50% compared to SC23 peak). The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.9). Three hour interval K indices: 00111110 (planetary), 00212211 (Boulder), 00001233 (Andenes).

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 266) and in 9 active regions using 1K resolution (SN: 163) SDO/HMI images.

AR 13916 [S14W64] decayed slowly and quietly.
AR 13917 [S07W53] produced several C flares and one M flare. The spot group still has a magnetic delta configuration.
AR 13920 [N21W15] was mostly quiet and gained a tiny magnetic delta configuration in a leading penumbra.
AR 13921 [S05W36] decayed slowly and quietly.
AR 13922 [S18E26] was the most active region on the visible disk, however, slow decay was observed after noon.
AR 13924 [S19W02] decayed slowly and was mostly quiet.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S10436 [S14W39] was quiet and stable.
S10442 [S08W14] developed slowly and quietly.
S10453 [N04W01] was quiet and stable.
S10461 [S19W52] decayed slowly and quietly.
S10462 [N11E63] was quiet and stable.
New region S10463 [S19E71] rotated into view with tiny spots.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.1 00:17 S07W39 13917 GOES16  
C2.9 00:28     GOES16  
C2.1 02:30   13916 GOES16  
C2.2 02:39   13916 GOES16  
M1.0 03:18 S18E37 13922 GOES16  
C2.6 03:25     GOES16  
C9.2 03:42 S17E38 13922 GOES16  
C2.0 09:58     GOES16  
M2.1 11:24 S08W49 13917 GOES16  
C4.2 13:09 S09W48 13917 GOES16  
M1.0 14:24   13922 GOES16  
C5.1 16:39   13917 GOES16  
C3.4 17:04     GOES16  
C4.1 17:08   13917 GOES16  
C9.9 17:21   13917 GOES16  
C2.0 19:35   13917 GOES16  
C4.7 20:50 S07W51 13917 GOES16  
C2.2 21:38   13924 GOES16  
C2.6 23:25 S17E38 13922 GOES16  

C1 flares: C1.4 @ 07:14, C1.6 @ 07:59, C1.6 @ 08:51, C1.8 @ 09:09, C1.3 @ 10:50, C1.4 @ 12:25, C1.4 @ 12:35, C1.9 @ 15:56, C1.7 @ 20:15, C1.7 @ 20:27, C1.9 @ 21:27 UT

Coronal mass ejections (CMEs)

December 11-13: 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 recurrent positive polarity northern hemisphere coronal hole (CH1262) was 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 fair to good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on December 14. A high speed stream associated with CH1262 could cause unsettled and active intervals on December 15-16.

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
13915 2024.12.02       N12W86            
13916 2024.12.02
2024.12.03
  2   S15W68 0002   BXO     was AR S10427

location: S15W64

13917 2024.12.03
2024.12.04
13 25 16 S08W56 0260 DKC DKC     beta-gamma-delta

was AR S10432

location: S07W53

area: 0550

S10436 2024.12.04   9 4 S14W39 0025   CRO      
S10441 2024.12.06       N31W58            
S10442 2024.12.06   6 3 S08W14 0012   BXO      
13920 2024.12.06
2024.12.08
14 44 23 N23W16 0260 EKI DAC     beta-gamma-delta

was AR S10443

area: 0420

location: N21W15

S10444 2024.12.06       N17W26            
S10446 2024.12.06       N19W47            
13919 2024.12.06
2024.12.08
      S14W62           was AR S10447

location: S14W56

13921 2024.12.07
2024.12.09
  3 1 S06W42 0005   BXO     was AR S10449
S10450 2024.12.07       N07W59            
S10452 2024.12.08       S09W41            
S10453 2024.12.08   2   N04W01 0003   BXO      
S10454 2024.12.08       S18W56            
S10455 2024.12.09       N07W09            
S10456 2024.12.09       N37W38            
13922 2024.12.09
2024.12.10
5 17 5 S18E22 0020 CSO CRI     was AR S10457

area: 0030

location: S18E26

13923 2024.12.10
2024.12.10
      N24W68           was AR S10457
13924 2024.12.11
2024.12.12
10 29 19 S20W02 0050 DAO DAI     beta-gamma-delta

was AR S10459

location: S19W02

area: 0280

S10460 2024.12.11       S14E08            
S10461 2024.12.12   2   S19W52 0003   BXO      
S10462 2024.12.12   4 2 N11E63 0015   CRO      
S10463 2024.12.13   3 2 S19E71 0010   BXO      
Total spot count: 42 146 75  
Sunspot number: 82 266 165  (total spot count + 10 * number of spotted regions)
Weighted SN: 72 175 104  (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): 90 146 132  

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
2024.11 199.6 195.3 152.5 (159.9 projected, -0.8) 9.33
2024.12 174.0 (1)   42.9 (2A) / 102.4 (2B) / - (2C) (157.8 projected, -2.1) (6.5)
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.