Solar Terrestrial Activity Report

Activity chart

Last major update issued on December 3, 2023 at 12:05 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 minor storm on December 2 under the weakening influence of CME effects. Solar wind speed at SOHO ranged between 393 and 761 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 148.2 - decreasing 6.6 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 158.41. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.3). Three hour interval K indices: 54110111 (planetary), 44212221 (Boulder), 55211101 (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 10 active regions using 2K resolution (SN: 178) and in 9 active regions using 1K resolution (SN: 128) SDO/HMI images.

Region 13494 [S17W80] was quiet and stable.
Region 13500 [S18W54] decayed slowly and continued to produce C flares. C1 flares: C1.7 @ 09:35, C1.7 @ 14:39 UT
Region 13501 [S09W47] was quiet and stable.
Region 13503 [N22W32] developed slowly and was mostly quiet.
Region 13505 [S17E17] gained spots and was quiet.
Region 13507 [N07E28] was quiet and stable.
Region 13508 [S15E26] was quiet and stable.
Region 13509 [N11W65] began to decay and was mostly quiet.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9194 [S06E37] lost the trailing spot while tiny leading polarity spots developed.
New region S9196 [S15E37] emerged with tiny spots.

AR 13492 produced a C1.8 flare @ 05:07, a C1.6 flare @ 18:27 and a C1.1 flare @ 23:09 UT.
AR 13493 was the source of a C1.5 @ 12:56, a C1.9 flare @ 14:08 and a C1.9 flare @16:26 UT.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.6 00:16   13500 GOES18  
C3.0 00:43   13500 GOES18  
C2.7 01:47   13492 GOES18  
C2.3 02:25   13492 GOES18  
C3.1 03:51   13500 GOES18  
C2.2 04:44   13492 GOES18  
C2.1 07:02   13509 GOES18  
C2.9 07:34   13492 GOES18  
C2.0 13:48   13500 GOES18  
C2.6 21:20   13503 GOES18  

Coronal mass ejections (CMEs)

November 30+December 2: 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 3-5 and quiet to active on December 6 due to effects from CH1190. The December 1 CME could contribute to the ongoing distrubance 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
13493 2023.11.20
2023.11.20
      S13W89        

 

13494 2023.11.20
2023.11.20
1 1 1 S17W82 0020 HSX HSX

area: 0070

13500 2023.11.22
2023.11.23
12 23 15 S18W58 0270 EKC EAC beta-gamma-delta

location: S18W54

area: 0320

13501 2023.11.22
2023.11.23
1 5 2 S08W49 0030 HSX CSO area: 0070

location: S09W47

13503 2023.11.23
2023.11.25
  12 4 N19W34 0020   BXO

locaton: N22W32

13506 2023.11.26
2023.11.29
      N15W71          

location: N15W60

13505 2023.11.27
2023.11.28
1 9 3 S18E16 0020 HSX CSO area: 0090
13508 2023.11.28
2023.11.29
1 4 2 S15E25 0060 HSX HSX area: 0190

location: S15E26

13507 2023.11.28
2023.11.29
1 4 3 N08E28 0130 HSX HSX area: 0240

location: N07E28

S9186 2023.11.28       S09W25            
S9188 2023.11.30       N09W59          
S9189 2023.11.30       N28W26            
S9190 2023.11.30       S10W50            
S9191 2023.11.30       S13W59            
13509 2023.12.01
2023.12.01
5 8 4 N10W65 0050 CSO DAO

location: N11W65

area: 0110

S9193 2023.12.01       S22W37          
S9194 2023.12.01   2   S06E37 0004   AXX  
S9196 2023.12.02   10 4 S15E37 0025   BXO  

 

Total spot count: 22 78 38  
Sunspot number: 92 178 128  (total spot count + 10 * number of spotted regions)
Weighted SN: 62 113 73  (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): 101 98 102  

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
2023.12 155.1 (1)   7.5 (2A) / 116.0 (2B) / 123.4 (2C) (132.7 projected, -1.4) (31.3)
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.