Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 10, 2024 at 06:45 UT. Revised on January 30, 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 to active levels on December 9 under the influence of a high speed stream from CH1259. Solar wind speed at SOHO ranged between 403 and 528 km/sec, averaging 470 km/sec (+106 compared to the previous day). The high latitude magnetometer at Andenes recorded quiet to major 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 172.5- increasing 22.2 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 187.84. In comparison SC24 peaked on June 28, 2014 at 145.50 while SC23 peaked on February 23, 2002 at 198.15. Current SC25 peak: 187.84 on June 10, 2024 (given a base solar flux level of 65, this is +52.59% compared to SC24 peak and -7.74% compared to SC23 peak). The Potsdam WDC planetary A index was 17 (STAR Ap - based on the mean of three hour interval ap indices: 16.8). Three hour interval K indices: 43233333 (planetary), 32343432 (Boulder), 54124456 (Andenes).

At the time of counting spots (see image time), spots were observed in 15 active regions using 2K resolution (SN: 342) and in 13 active regions using 1K resolution (SN: 239) SDO/HMI images.

AR 13916 [S16W12] decayed slowly and was mostly quiet.
AR 13917 [S08E00] produced a few C flares and decayed slowly.
AR 13919 [S14W04] decayed slowly and quietly.
AR 13920 [N22E39] was mostly quiet and stable.
New AR 13921 [S04E14] emerged on December 7 and was numbered 2 days later by SWPC.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S10418 [S07W75] decayed further producing many C flares.
S10433 [S08W16] was quiet and stable.
S10436 [S15E21] was quiet and stable.
S10442 [S08E40] decayed slowly and quietly.
S10444 [N20E05] reemerged with tiny spots.
S10448 [S17W53] developed slowly and quietly.
S10451 [S08W16] was quiet and stable.
New region S10455 [N07E45] emerged with tiny spots.
New region S10456 [N37E14] emerged with a tiny spot at a high latitude.
New region S10457 [S17E76] rotated into view with a few spots.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.7 00:53   13913 GOES16  
C3.6 01:30   13917 GOES16  
C2.6 02:10   13913 GOES16  
C2.4 04:21   13920 GOES16  
C2.2 04:47   13913 GOES16  
C2.2 05:56     GOES16  
C2.7 06:06     GOES16  
C4.4 06:22 S06W66 S10418 GOES16  
C2.3 07:13     GOES16  
C2.5 07:45   13917 GOES16  
C2.1 08:24   13917 GOES16  
C2.8 09:42   S10418 GOES16  
C3.7 10:15   13917 GOES16  
C2.6 12:17     GOES16  
C6.3 12:27   S10418 GOES16  
C2.5 15:11   S10418 GOES16  
C8.4/1F 16:12 S04W75 S10418 GOES16  
C2.9 19:47   S10418 GOES16  
C2.3 22:40   S10418 GOES16  
C2.4 22:46     GOES16  
C2.6 23:30   S10418 GOES16  

C1 flares: C1.6 @ 02:43, C1.7 @ 03:35, C1.9 @ 03:46, C1.7 @ 07:32, C1.8 @ 08:50, C1.8 @ 09:37, C1.6 @ 10:51, C1.9 @ 13:18, C1.7 @ 14:27, C1.6 @ 17:28, C1.8 @ 20:33, C1.6 @ 21:48, C1.6 @ 23:22, C1.9 @ 23:50 UT

Coronal mass ejections (CMEs)

December 7-9: 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 (CH1259) was in an Earth facing position on December 6-7. A positive polarity northern hemisphere coronal hole (CH1261) will be rotating 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 likely 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 to unsettled on December 10-14, first due to effects from CH1259 and then from CH1261.

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     S06W75 0220 DAI       SWPC moved this AR to the location of AR S10418 on 2024.12.01
STAR data is for the original spot group

location: S08W91

S10418 2024.11.28   11 8 S07W75 0170   DAO     beta-gamma

see AR 13912

13915 2024.12.02       N12W30            
13916 2024.12.02
2024.12.03
8 32 20 S15W12 0040 CRO CRI     was AR S10427

area: 0090

S10431 2024.12.03       N10W55            
13917 2024.12.03
2024.12.04
12 64 36 S08W02 0220 DAO DSC     beta-gamma

was AR S10432

location: S08E00

area: 0560

S10433 2024.12.04   6 1 S11W32 0010   AXX      
S10434 2024.12.04       S14W50            
S10436 2024.12.04   9   S15E21 0015   BXO      
S10438 2024.12.05       N15E26            
S10440 2024.12.05       N22W36            
S10441 2024.12.06       N28W08            
S10442 2024.12.06   4   S08E40     BXO      
13920 2024.12.06
2024.12.08
6 28 12 N22E38 0070 CSO DAI     was AR S10443

location: N22E39

area: 0100

S10444 2024.12.06   2 1 N20E05 0003   AXX      
S10445 2024.12.06       N09W27            
S10446 2024.12.06       N22E01            
13919 2024.12.06
2024.12.08
2 7 3 S14W06 0010 BXO CRO     was AR S10447

location: S14W04

area: 0020

S10448 2024.12.07   6 3 S17W53 0020   CRO      
13921 2024.12.07
2024.12.09
  6 4 S07E12 0020 HRX CRO     was AR S10449
S10450 2024.12.07       N07W07            
S10451 2024.12.07   8 2 S08W16 0015   BXO      
S10452 2024.12.08       S09E11            
S10453 2024.12.08       N00E49            
S10454 2024.12.08       S18W04            
S10455 2024.12.09   3 2 N07E45 0008   BXO      
S10456 2024.12.09   1 1 N37E14 0003   AXX      
S10457 2024.12.09   5 2 S17E76 0050   CRO      
Total spot count: 34 192 95  
Sunspot number: 94 342 225  (total spot count + 10 * number of spotted regions)
Weighted SN: 55 212 125  (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): 103 188 180  

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
2024.12 178.4 (1)   29.6 (2A) / 102.1 (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.