Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 29, 2024 at 06:20 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 to unsettled on January 28, under the influence of effects from CH1199 after noon. Solar wind speed at SOHO ranged between 342 and 513 km/sec. The high latitude magnetometer at Andenes recorded quiet to major storm levels. The above 10 MeV proton flux was at background levels, however, the major M6 flare in AR 13559 early on January 29 caused an increase in proton levels from 04:50 UT and the 10 MeV proton flux exceed event levels at 06:10 UT.

Solar flux density measured at 20h UT on 2.8 GHz was 141.1 - increasing 5.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.02. 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 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.0). Three hour interval K indices: 11121133 (planetary), 11122223 (Boulder), 02111265 (Andenes).

The background x-ray flux is at the class C2 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 176) and in 8 active regions using 1K resolution (SN: 104) SDO/HMI images.

Region 13559 [N25W73] decayed slowly and was mostly quiet. The region was the source of a major M6.8 proton flare at 04:38 UT on January 29. C1 flares: C1.8 @ 14:25 UT
Region 13560 [S11W76] decayed quickly and quietly.
Region 13563 [S07E04] was quiet and stable.
New region 13565 [N05E65] rotated into view on January 27 and was numbered the next day by SWPC as the region developed slowly. The region has a magnetic delta and produced an M2.5 flare at 05:39 UT on January 29. C1 flares: C1.2 @ 22:24 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9346 [N28W60] decayed slowly and quietly. The region was the source of an M1.2 flare at 01:40 UT on January 29.
S9366 [N21E45] reemerged with tiny spots. C1 flare: C1.6 @ 18:13 UT
S9371 [S07E45] was mostly quiet and stable. C1 flare: C1.5 @ 22:36 UT
S9374 [N07W24] reemerged with a tiny spot.
S9378 [S12W34] was quiet and stable.
S9379 [N31E08] was quiet and stable.
New region S9381 [N17E84] rotated partly into view and could produce M flares. C1 flares: C1.2 @ 20:18 UT
New region S9382 [S13E32] was observed with a tiny spots in an old plage area.

AR 13555 behind the southwest limb produced a C1.5 flare at 17:49 UT

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.2 07:18     GOES16  
C3.4 10:17   13561 GOES16 LDE
C2.5 11:31   13561 GOES16  
C2.8 12:46 behind southwest limb 13561 GOES16  
C3.2 13:17   13559 GOES16  
C2.1 13:40   13561 GOES16  
C3.0 16:00   S9346 GOES16 simultaneous flares in ARs S9381 and 13560
C3.4 23:34   S9381 GOES16  

Coronal mass ejections (CMEs)

January 26-28: 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) was 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 poor. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January 29-30 due to effects from CH1199 and quiet on January 31.

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
13559 2024.01.17
2024.01.18
11 9 5 N26W70 0280 FKO CKO

location: N25W73

area: 0360

SWPC includes AR S9346

13560 2024.01.17
2024.01.18
7 10 5 S11W75 0130 DAI DRI area: 0050
S9346 2024.01.19   1 1 N28W60 0030   HRX  
S9362 2024.01.23       S23W42            
S9364 2024.01.24       S10W19            
S9366 2024.01.25   7 1 N21E43 0013   BXO    
S9367 2024.01.25       N31E09            
S9368 2024.01.25       S26W11            
13563 2024.01.26
2024.01.26
5 9 4 S07E03 0010 BXO CRO location: S07E04

area: 0020

S9369 2024.01.26       N24W26            
S9370 2024.01.26       N15E14            
S9371 2024.01.26   2   S07E45 0002   AXX  
S9372 2024.01.26       N24W41            
S9373 2024.01.26       N11W37            
S9374 2024.01.26   1 1 N07W24 0003   AXX    
S9375 2024.01.26       S21E14            
S9377 2024.01.27       S10W07          
S9378 2024.01.27   6 3 S12W34 0015   CRO  
S9379 2024.01.27   2   N31E08 0003   AXX  
13565 2024.01.27
2024.01.28
1 7 4 N07E62 0010 HRX DRI beta-delta

location: N05E65

area: 0050

13564 2024.01.28 1     S09E54 0010 AXX       not sure what SWPC observed here
There were no spots at that location
S9381 2024.01.28   1   N17E84 0090   HSX    
S9382 2024.01.28   1   S13E32 0002   AXX    
Total spot count: 25 56 24  
Sunspot number: 75 176 104  (total spot count + 10 * number of spotted regions)
Weighted SN: 43 86 54  (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): 83 97 83  

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
2024.01 167.5 (1)   116.1 (2A) / 128.5 (2B) / 159.0 (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.