Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 23, 2024 at 08:05 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 (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 active on January 22. Solar wind speed at SOHO ranged between 360 and 465 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux lifted above background levels early in the day and increased slowly until reaching a peak of 7.1 pfu at 16:50 UT. What was likely the January 20 CME was observed reaching DSCOVR just after 16h UT and caused a relatively weak geomagnetic disturbance after 18h UT. The peak proton flux coincided with the time the CME reached Earth.

Solar flux density measured at 20h UT on 2.8 GHz was 196.1 - increasing 41.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.06. 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 9 (STAR Ap - based on the mean of three hour interval ap indices: 8.8). Three hour interval K indices: 10112234 (planetary), 10112234 (Boulder), 10122123 (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 15 active regions using 2K resolution (SN: 395) and in 11 active regions using 1K resolution (SN: 244) SDO/HMI images.

Region 13549 [S21W67] was quiet and stable.
Region 13553 [N03W49] decayed further and could soon become spotless.
Region 13555 [S12W26] developed with new flux emerging to the south of the leader spot.
Region 13556 [N15W14] decayed slowly and quietly.
Region 13557 [S21W02] was quiet and stable.
Region 13559 [N27E08] could produce major flares. The spot group lost many intermediate spots. The complexity arises from the near merger with AR S9346 with the leader spots of the latter region very close to the trailing spots of AR 13559. The total longitudinal span of the two regions is 22 degrees. C1 flares: C1.9 @ 09:13 UT
Region 13560 [S10E06] developed slowly and quietly. The region has weak polarity intermixing.
Region 13561 [S15W31] developed further and has a weak magnetic delta structure in the central spot section. Major flare are possible due to possible interaction with nearby regions AR 13555 and S9357. The latitudinal separation between ARs 13561 and S9357 is minimal and the two regions could merge.
Region 13562 [S08W40] decayed slowly and quietly.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9338 [N30W41] decayed slowly and quietly.
S9346 [N28E18] is compact and has significant polarity intermixing. The region gained spots and area and could produce a major flare itself or with AR 13559.
S9351 [S20W23] decayed slowly and quietly.
S9357 [S17W30] developed and gained a magnetic delta structure in the leading penumbra. Spots in this group and in AR 13561 are very close to each other and major flaring is possible.
New region S9360 [S09W21] emerged with tiny spots.
New region S9361 [S05W02] was observed with tiny spots in an old plage area.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.3 00:13   13559 GOES16  
C2.9 00:32 N25E32 13559 GOES16  
C6.5 01:47 N26E23 13559 GOES16  
C3.6 03:14   13559 GOES16  
C3.3 03:28   S9346 GOES16  
C5.3 04:14   S9346 GOES16  
M1.5/1N 06:22 N29E27 S9346 GOES16  
C3.7 07:04     GOES16  
C5.2 07:28   S9346 GOES16  
C3.1 08:01   13559 GOES16 simultaneous flare in AR S9346
C5.8 08:25 N28E24 S9346 GOES16  
C2.2 09:39   S9346 GOES16  
C7.0 11:27   S9357 GOES16 incorrectly attributed to AR 13559 by SWPC. Flare may have been triggered by filament eruption just south of this region
C5.8 12:20   S9346 GOES16  
C5.5 12:31   S9346 GOES16  
C3.5 13:14   13559 GOES16  
C2.6 14:38 behind southwest limb   GOES16  
C3.3 15:41   13561 GOES16  
C3.7 16:04   S9346 GOES16  
C7.0 16:49   13561 GOES16  
C3.9 17:26   S9346 GOES16  
C5.2 17:48   S9357 GOES16  
C5.5 17:50   S9346 GOES16  
C5.3 18:04   S9346 GOES16  
C4.5 18:50   S9346 GOES16 simultaneous flare in AR S9357
C8.1 19:05   S9357 GOES16  
M1.1 19:24   13559 GOES16  
M1.2 19:32   13559 GOES16 simultaneous flare in AR 13561
M2.0/1F 19:47   13561 GOES16 flare involved AR S9357
C3.4 20:52   S9346 GOES16  
M3.4 21:21   13561 GOES16 flare involved AR S9357
M2.5 21:27   13561 GOES16 flare involved AR S9357
M1.6 21:43   S9357 GOES16  
M2.1 22:22   13561 GOES16 simultaneous flare in AR S9357
C5.2 22:52   13555 GOES16  
C4.5 23:14   S9346 GOES16  
C3.8 23:52   S9357    

Coronal mass ejections (CMEs)

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.
January 21: A partial halo CME was observed after a C4 flare in AR 13559, including filaments to the southeast, early in the day. There is a slight chance that the outer edge of the CME could reach Earth.
January 22: A partial halo CME was observed after a large filament eruption in the southwest quadrant after 09h UT. The CME could cause a disturbance on January 25.

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 likely become Earth facing on January 24-25.

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 23 due to CME effects and quiet on January 24. Quiet to active is likely on January 25 due to CME effects.

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
13551 2024.01.10
2024.01.12
      N26W78          

location: N27W75

13549 2024.01.10
2024.01.12
1 2 1 S17W69 0160 HSX CKO

area: 0340

location: S21W67

13553 2024.01.13
2024.01.13
1 3 1 N05W51 0010 AXX BXO location: N03W49

area: 0005

13554 2024.01.13
2024.01.15
      N07W46          

location: N07W39

S9324 2024.01.13       S19W37            
13555 2024.01.14
2024.01.15
2 22 8 S12W26 0080 HSX DAO

area: 0220

S9329 2024.01.15       S19W24            
13556 2024.01.15
2024.01.16
2 6 4 N17W16 0040 HAX HAX location: N15W14
13557 2024.01.16
2024.01.16
  5   S13W10 0012   AXX

location: S21W02

13561 2024.01.16
2024.01.19
14 45 27 S15W28 0090 DAI DAC beta-gamma-delta

area: 0350

location: S15W31

S9333 2024.01.16       N11W29            
13559 2024.01.17
2024.01.18
32 36 23 N27E11 0360 FKC EKO beta-gamma

area: 0820

location: N27E08

SWPC includes AR S9346

13560 2024.01.17
2024.01.18
4 34 20 S11E08 0040 CAO DRI

beta-gamma

location: S10E07

area: 0110

S9337 2024.01.17       S19W55            
S9338 2024.01.17   1   N30W41 0001   AXX  
S9340 2024.01.17       N11W40            
S9341 2024.01.18       S11W54            
S9342 2024.01.18       S10W29            
S9343 2024.01.18       N22E05            
S9344 2024.01.18       S02W48            
S9346 2024.01.19   37 22 N28E18 0270   DAC beta-gamma
S9347 2024.01.19       S23W39            
S9348 2024.01.19       N12W44            
13562 2024.01.20
2024.01.20
3 15 9 S09W42 0090 DAO DAO

location: S08W40

S9351 2024.01.20   3   S20W23 0003   AXX  
S9352 2024.01.20       S33W41          
S9353 2024.01.20       N26W15          
S9355 2024.01.20       N14E06            
S9357 2024.01.21   28 17 S17W30 0130   DAC beta-gamma-delta
S9358 2024.01.21       N10W04          
S9360 2024.01.22   5 2 S09W21 0012   CRO    
S9361 2024.01.22   3   S05W02 0006   AXX    
Total spot count: 59 245 134  
Sunspot number: 139 395 244  (total spot count + 10 * number of spotted regions)
Weighted SN: 99 301 190  (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): 153 217 195  

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
2024.01 169.6 (1)   98.2 (2A) / 138.3 (2B) / 157.1 (2C) (117.9 projected, -3.3) (5.3)
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.