Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 27, 2024 at 09:55 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 26. Solar wind speed at SOHO ranged between 375 and 507 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at background levels.

Solar flux density measured at 20h UT on 2.8 GHz was 156.5 - increasing 16.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.00. 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 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.0). Three hour interval K indices: 01012212 (planetary), 11002312 (Boulder), 12001235 (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 14 active regions using 2K resolution (SN: 237) and in 7 active regions using 1K resolution (SN: 110) SDO/HMI images.

Region 13555 [S13W81] decayed slowly and was mostly quiet.
Region 13559 [N26W47] decayed further and was mostly quiet.
Region 13560 [S10W47] developed slowly and was mostly quiet. C1 flares: C1.3 @ 07:24, C1.6 @ 15:40 UT
New region 13563 [S06E31] emerged with tiny spots.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9346 [N28W34] decayed slowly and quietly.
S9357 [S18W81] decayed slowly and was mostly quiet.
S9366 [N21E69] rotated fully into view and decayed slowly.
New region S9369 [N24W00] emerged with tiny spots.
New region S9370 [N15E40] emerged with tiny spots.
New region S9371 [S09E72] rotated into view with tiny spots.
New region S9372 [N24W15] emerged with a tiny spot.
New region S9373 [N11W11] emerged with tiny spots.
New region S9374 [N09E11] emerged with tiny spots.
New region S9375 [S21E40] emerged with tiny spots.

AR 13561 produced C1 flares while at the southwest limb: C1.3 @ 03:07, C1.9 @ 03:31, C1.4 @ 04:29, C1.4 @ 06:44, C1.4 @ 08:54, C1.2 @ 10:33, C1.5 @ 21:18, C1.4 @ 23:17 UT

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C9.0 00:33   13561 GOES16  
C9.0 04:59   13561 GOES16  
C2.0 15:16   13561 GOES16  
C2.1 16:19   13561 GOES16  
C2.3 17:11   13561 GOES16  
C2.0 18:18   13561 GOES16 incorrectly attributed to AR 13559 by SWPC
C3.0 20:24 S08W45 13560 GOES16  

Coronal mass ejections (CMEs)

January 24-26: 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 negative polarity southern hemisphere coronal hole (CH1199) will be Earth facing on January 26-28. A negative polarity northern hemisphere coronal hole (CH1200) was Earth facing on January 25-26, CH1200 is probably too far to the north to cause a disturbance.

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 on January 27. Effects from CH1199 could reach Earth late on January 28 and cause quiet to minor storm conditions until January 30.

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
13555 2024.01.14
2024.01.15
3 4 3 S26W81 0140 CAO CSO

location: S13W81

SWPC location is way off

13556 2024.01.15
2024.01.16
      N16W72         location: N17W65
13557 2024.01.16
2024.01.16
      S13W67        

location: S24W45

13561 2024.01.16
2024.01.19
6     S17W85 0180 DAC    

rotated out of view

13559 2024.01.17
2024.01.18
17 33 17 N25W46 0480 FKI EAO

location: N26W47

SWPC includes AR S9346

13560 2024.01.17
2024.01.18
8 24 10 S22W48 0040 DAI DAO

location: S10W47

area: 0190

SWPC location is way off

S9343 2024.01.18       N22W47            
S9346 2024.01.19   10 3 N28W34 0060   CAO  
13562 2024.01.20
2024.01.20
1     S08W97 0010 AXX      

spotless last 2 days

rotated out of view

S9355 2024.01.20       N14W46            
S9357 2024.01.21   4 3 S18W81 0020   BXO  
S9358 2024.01.21       N10W56            
S9361 2024.01.22       S05W54            
S9362 2024.01.23       S23W16            
S9363 2024.01.23       S49W45            
S9364 2024.01.24       S10E07            
S9366 2024.01.25   3   N21E69 0006   BXO  
S9367 2024.01.25       N31E35          
S9368 2024.01.25       S26E15          
13563 2024.01.26
2024.01.26
2 4 3 S06E32 0010 BXO CRO   location: S06E31
S9369 2024.01.26   2   N24W00 0003   AXX    
S9370 2024.01.26   3   N15E40 0005   BXO    
S9371 2024.01.26   2 1 S09E72 0006   HRX    
S9372 2024.01.26   1   N24W15 0002   AXX    
S9373 2024.01.26   2   N11W11 0002   BXO    
S9374 2024.01.26   2   N09E11 0003   AXX    
S9375 2024.01.26   3   S21E40 0004   BXO    
Total spot count: 37 97 40  
Sunspot number: 97 237 110  (total spot count + 10 * number of spotted regions)
Weighted SN: 62 123 66  (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): 107 130 88  

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
2024.01 169.2 (1)   112.0 (2A) / 133.5 (2B) / 159.8 (2C) (117.9 projected, -3.3) (5.5)
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.