Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 21, 2024 at 08:30 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 (January 1, 2024)
Solar cycle Solar cycles 23-25 (January 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (January 1, 2024) 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 (January 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (January 1, 2024) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (January  3, 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 quiet on January 20. Solar wind speed at SOHO ranged between 353 and 416 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 166.3 - decreasing 17.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.14. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 158.71 on June 27, 2023). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.6). Three hour interval K indices: 22112211 (planetary), 12223212 (Boulder), 43212332 (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 20 active regions using 2K resolution (SN: 413) and in 18 active regions using 1K resolution (SN: 289) SDO/HMI images.

Region 13545 [S05W78] was quiet and stable.
Region 13549 [S21W41] was quiet and stable.
Region 13553 [N04W23] decayed further and was mostly quiet.
Region 13555 [S12E02] was mostly quiet and stable.
Region 13556 [N15E12] was quiet and stable.
Region 13557 [S24E28] was quiet and stable.
Region 13559 [N26E32] developed quickly after noon and was the source of several low level C flares. The region was the source of a C5.3 flare at 00:41 and a C6.3 flare at 02:02 UT on January 21. A partial halo CME was observed after these events. C1 flares: C1.7 @ 02:58, C1.6 @ 12:02, C1.2 @ 17:07, C1.5 @ 18:26, C1.2 @ 21:19, C1.4 @ 22:09, C1.5 @ 22:22, C1.5 @ 22:55, C1.7 @ 23:32, C1.8 @ 23:51 UT
Region 13560 [S10E34] developed slowly and was mostly quiet. C1 flares: C1.4 @ 12:32, C1.7 @ 12:53, C1.7 @ 13:58, C1.3 @ 21:51 UT
Region 13561 [S16W03] developed further and was mostly quiet.
New region 13562 [S09W13] emerged with several spots and could produce C flares.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9337 [S19W29] was quiet and stable.
S9338 [N20W18] was quiet and stable.
S9346 [N29E44] developed slowly and was mostly quiet. C1 flares: C1.1 @ 16:04 UT
S9347 [S23W13] was quiet and stable.
S9348 [N12W18] was quiet and stable.
New region S9351 [S20E02] emerged with tiny spots.
New region S9352 [S34W15] emerged with tiny spots.
New region S9353 [N26E07] was observed with tiny spots in an old plage area.
New region S9354 [N11W43] emerged with a tiny spot.
New region S9355 [N14E32] emerged with tiny spots.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.5 09:34   13555 GOES16 LDE, halo CME
simultaneous flare in AR S9346
C2.8 11:14   13559 GOES16  
C5.2 14:34   13559 GOES16  

Coronal mass ejections (CMEs)

January 18-19: No obviously Earth directed CME observed.
January 20: A full halo CME was observed in LASCO imagery after a C3.5 long duration event involving filament eruptions just south of AR 13555. The CME could reach Earth between late on January 22 and noon on January 23.

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 (CH1198) was Earth facing on January 16-18.

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 to unsettled on January 21 due to effects from CH1198 and quiet on January 22. Late on January 22 or early on January 23 the January 20 CME could reach Earth and cause unsettled to minor storm conditions.

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
13545 2024.01.08
2024.01.09
2 2 2 S06W79 0130 HAX HHX area: 0300

location: S05W78

13550 2024.01.09
2024.01.12
      S18W87            
13551 2024.01.10
2024.01.12
      N26W50        

location: N27W49

13548 2024.01.10
2024.01.12
      N15W66           location: N12W62
13549 2024.01.10
2024.01.12
3 9 4 S21W41 0180 CSO CHO

area: 0350

13553 2024.01.13
2024.01.13
1 8 2 N05W23 0040 HAX CAO location: N04W23
13554 2024.01.13
2024.01.15
      N07W16        

location: N07W13

S9324 2024.01.13       S19W11            
13555 2024.01.14
2024.01.15
6 14 10 S12E04 0150 CSO DSO

area: 0190

S9327 2024.01.14       N12W41            
S9328 2024.01.14       N21W44            
S9329 2024.01.15       S19E02            
13556 2024.01.15
2024.01.16
1 8 2 N15E12 0090 HAX CSO

area: 0100

13557 2024.01.16
2024.01.16
  7 2 S13E18 0013   BXO

location: S24E28

13561 2024.01.16
2024.01.19
6 20 13 S16W03 0080 DAO DAO area: 0150
S9333 2024.01.16       N11W03            
S9334 2024.01.16       N13W35            
13559 2024.01.17
2024.01.18
22 53 29 N27E35 0220 EAI EKI beta-gamma-delta

area: 0470

location: N26E32

13560 2024.01.17
2024.01.18
8 28 17 S10E35 0040 BXI DRI beta-gamma

location: S10E34

area: 0080

S9337 2024.01.17   5 1 S19W29 0010   AXX  
S9338 2024.01.17   6   N20W18 0010   BXO  
S9339 2024.01.17       N25W37          
S9340 2024.01.17       N11W14            
S9341 2024.01.18       S11W28            
S9342 2024.01.18       S10W03          
S9343 2024.01.18       N22E31            
S9344 2024.01.18       S02W22            
S9346 2024.01.19   7 4 N29E44 0030   CRO  
S9347 2024.01.19   9 2 S23W13 0020   BXO  
S9348 2024.01.19   3 1 N12W18 0005   BXO  
13562 2024.01.20
2024.01.20
5 18 12 S09W14 0030 CRO DAO   was AR S9350

location: S09W13

area: 0120

S9351 2024.01.20   5 3 S20E02 0012   BXO    
S9352 2024.01.20   5 3 S34W15 0013   BXO    
S9353 2024.01.20   3   N26E03 0005   AXX    
S9354 2024.01.20   1 1 N11W43 0004   AXX    
S9355 2024.01.20   2 1 N14E32 0004   BXO    
Total spot count: 54 213 109  
Sunspot number: 144 413 289  (total spot count + 10 * number of spotted regions)
Weighted SN: 92 274 170  (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): 158 227 231  

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
2022.05 133.8 136.8 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
2023.06 161.7 166.8 160.5 125.0 (+1.1)
(SC25 solar max candidate)
8.95
2023.07  176.4 182.2 160.0 (124.6 projected, -0.4) 8.15
2023.08  153.7 157.6 114.8 (124.1 projected, -0.5) 7.19
2023.09  154.4 156.0 134.2 (123.8 projected, -0.3) 14.26
2023.10  142.8 141.9 99.4 (124.6 projected, +0.8) 8.16
2023.11 153.5 150.2 105.4 (124.6 projected, +0.0) 12.20
2023.12 151.1 146.4 114.2 (121.2 projected, -3.4) 9.60
2024.01 167.8 (1)   88.8 (2A) / 137.7 (2B) / 154.0 (2C) (117.9 projected, -3.3) (5.2)
2024.02       (117.1 projected, -0.8)  
2024.03       (116.6 projected, -0.5)  
2024.04       (116.6 projected, +0.0)  
2024.05       (117.0 projected, -0.8)  
2024.06       (114.9 projected, -2.1)  

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 January 3, 2024

The relatively low solar activity during the last months of 2023 significantly increased the possibility that solar cycle 25 has already peaked. Whether the first peak in June 2023 will be the actual solar max will not be known for some time. Due to the relatively high solar activity early in 2023 it is unlikely there will be another solar max candidate, if at all, until at least May 2024. Both the northern and southern polar fields, as well as the averaged total field, have already reversed polarities.

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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.