Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 28, 2024 at 10:30 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 27. Solar wind speed at SOHO ranged between 322 and 463 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux was at background levels.

Solar flux density measured at 20h UT on 2.8 GHz was 148.1 - increasing 1.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.01. 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 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.3). Three hour interval K indices: 21111111 (planetary), 22221221 (Boulder), 41110000 (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: 164) and in 8 active regions using 1K resolution (SN: 112) SDO/HMI images.

Region 13559 [N26W60] decayed slowly and was mostly quiet.
Region 13560 [S11W61] developed early in the day, then decayed slowly after noon. C1 flares: C1.8 @ 01:49, C1.2 @ 11:16, C1.5 @ 14:58 UT
Region 13563 [S07E18] decayed and was spotless by noon, later on a few tiny spots formed.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9346 [N27W47] decayed slowly and quietly.
S9371 [S09E58] was quiet and stable.
S9376 [S21W80] emerged early in the day, then decayed slowly after noon.
New region S9377 [S10E06] emerged with tiny spots.
New region S9378 [S13W22] emerged with tiny spots.
New region S9379 [N30E19] emerged with tiny spots.
New region S9380 [N06E78] rotated into view with a small, mature spot. C1 flares: C1.5 @ 22:12 UT

AR 13561 produced C1 flares from behind the southwest limb: C1.3 @ 00:43, C1.6 @ 03:54, C1.7 @ 04:27, C1.3 @ 13:41 UT

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.2 06:36   13560 GOES16  
C2.0 09:41 behind southwest limb 13561 GOES16  
C2.9 10:39 behind southwest limb 13561 GOES16  
C2.2 23:11   13559 GOES16  

Coronal mass ejections (CMEs)

January 25-27: 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 25-27, 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 fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to active on January 28-30 due to effects from CH1199.

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
13556 2024.01.15
2024.01.16
      N16W86           location: N17W78
13557 2024.01.16
2024.01.16
      S13W81          

location: S24W58

13559 2024.01.17
2024.01.18
14 20 10 N26W56 0310 FKI CKO

location: N26W60

area: 0420

SWPC includes AR S9346

13560 2024.01.17
2024.01.18
6 19 11 S11W61 0120 DAI DAO  
S9346 2024.01.19   2 2 N27W47 0050   HAX  
S9362 2024.01.23       S23W29            
S9363 2024.01.23       S49W58            
S9364 2024.01.24       S10W06            
S9366 2024.01.25       N21E56          
S9367 2024.01.25       N31E22            
S9368 2024.01.25       S26E02            
13563 2024.01.26
2024.01.26
2 5 2 S07E18 0010 BXO BXO  
S9369 2024.01.26       N24W13          
S9370 2024.01.26       N15E27          
S9371 2024.01.26   1   S09E58 0002   AXX  
S9372 2024.01.26       N24W28          
S9373 2024.01.26       N11W24          
S9374 2024.01.26       N09W02          
S9375 2024.01.26       S21E27          
S9376 2024.01.27   2   S21W80 0003   BXO    
S9377 2024.01.27   5 1 S10E06 0012   BXO    
S9378 2024.01.27   7 3 S13W22 0020   BXO    
S9379 2024.01.27   2 2 N30E19 0008   BXO    
S9380 2024.01.27   1 1 N06E78 0020   HRX    
Total spot count: 22 64 32  
Sunspot number: 52 164 112  (total spot count + 10 * number of spotted regions)
Weighted SN: 37 87 55  (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): 57 90 90  

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
2024.01 168.4 (1)   113.7 (2A) / 130.5 (2B) / 159.4 (2C) (117.9 projected, -3.3) (5.4)
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.