Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 4, 2023 at 06:50 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 to unsettled on December 3. Solar wind speed at SOHO ranged between 390 and 562 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels.

Solar flux density measured at 20h UT on 2.8 GHz was 139.2 - decreasing 7.0 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 158.42. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 9.9). Three hour interval K indices: 23222232 (planetary), 23122322 (Boulder), 22332334 (Andenes).

The background x-ray flux is at the class B7 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 212) and in 11 active regions using 1K resolution (SN: 161) SDO/HMI images.

Region 13500 [S18W68] decayed slowly and saw decreased flare activity. C1 flares: C1.3 @ 21:11 UT
Region 13501 [S09W62] decayed slowly and quietly.
Region 13503 [N22W38] decayed slowly and quietly.
Region 13505 [S16E04] was mostly quiet and stable.
Region 13507 [N07E15] developed slowly and was mostly quiet .C1 flares: C1.3 @ 19:55 UT
Region 13508 [S14E13] was quiet and stable.
Region 13509 [N12W78] decayed slowly and quietly.
New region 13510 [S15E22] emerged on December 2 and was numbered by SWPC the next day. C class flaring is possible. C1 flares: C1.5 @ 07:33, C1.1 @ 23:17 UT
New region 13511 [S22E23] emerged with several spots and was polarity intermixing and possibly a weak magnetic delta in the central spot section. A minor M class flare is possible. C1 flares: C1.2 @ 10:59, C1.5 @ 15:20 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
New region S9197 [S09E72] rotated into view.
New region S9199 [N15E02] emerged with tiny spots.
New region S9200 [N05E22] emerged with tiny spots.
New region S9201 [S16W07] emerged with tiny spots.

AR 13492 behind the northwest limb produced a C1.7 flare at 05:15 UT.
AR 13494 behind the southwest limb was the source of a C1.4 flare at 16:58 UT

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C4.0 08:06   13494 GOES18  
C2.8 14:36 behind northwest limb 13492 GOES18  
C2.7 22:37   13500 GOES18  

Coronal mass ejections (CMEs)

December 2-3: No obviously Earth directed CMEs were observed.
December 1: A partial halo CME was observed after an M1.0 flare in AR 13500 late in the day. This CME could reach Earth on December 4 or 5 and contribute to the expected CH1190 disturbance.

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) rotated 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 quiet to major storm on December 4-5 and quiet to active on December 6 due to effects from CH1190. The December 1 CME could contribute to the ongoing disturbance on December 4-5.

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
13500 2023.11.22
2023.11.23
9 14 8 S18W71 0250 DKC EAI beta-gamma

location: S18W68

13501 2023.11.22
2023.11.23
1 2 1 S08W62 0020 HSX HAX area: 0050

location: S09W62

13503 2023.11.23
2023.11.25
  2 1 N19W48 0007   BXO

locaton: N22W38

13506 2023.11.26
2023.11.29
      N15W85          

location: N15W73

13505 2023.11.27
2023.11.28
3 6 4 S17E03 0020 CSO CSO area: 0090

location: S16E04

13508 2023.11.28
2023.11.29
1 1 1 S15E12 0060 HSX HSX area: 0180

location: S14E13

13507 2023.11.28
2023.11.29
2 10 7 N08E14 0130 HSX DSO area: 0250

location: N07E15

S9186 2023.11.28       S09W38            
S9189 2023.11.30       N28W39            
13509 2023.12.01
2023.12.01
2 4 2 N11W79 0030 CRO HRX

location: N12W78

S9193 2023.12.01       S22W50            
S9194 2023.12.01       S06E24          
13510 2023.12.02
2023.12.03
6 20 14 S15E22 0030 CRI DAO area: 0180
S9197 2023.12.03   3 2 S09E72 0050   HRX    
13511 2023.12.03
2023.12.03
3 14 10 S23E23 0010 BXO DRI   beta-gamma

was AR S9198

location: S22E23

area: 0090

S9199 2023.12.03   2   N15E02 0002   BXO    
S9200 2023.12.03   2 1 N05E22 0005   BXO    
S9201 2023.12.03   2   S16W07 0005   BXO    
Total spot count: 27 82 51  
Sunspot number: 107 212 161  (total spot count + 10 * number of spotted regions)
Weighted SN: 63 121 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): 118 117 129  

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
2023.12 149.8 (1)   10.9 (2A) / 113.0 (2B) / 122.9 (2C) (132.7 projected, -1.4) (24.1)
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.