Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 22, 2024 at 07:15 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 21. Solar wind speed at SOHO ranged between 324 and 395 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled levels.

Solar flux density measured at 20h UT on 2.8 GHz was 178.5 - increasing 11.8 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 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 01122111 (planetary), 11232212 (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 17 active regions using 2K resolution (SN: 366) and in 16 active regions using 1K resolution (SN: 262) SDO/HMI images.

Region 13549 [S21W53] was mostly quiet and stable. C1 flares: C1.8 @ 21:18 UT
Region 13553 [N04W37] decayed further and was quiet.
Region 13555 [S12W12] decayed slowly and quietly.
Region 13556 [N15W01] was quiet and stable.
Region 13557 [S22E10] was quiet and stable.
Region 13559 [N26E20] developed further gaining area and was the source of many C flares. The region has polarity intermixing and could produce M flares. The proximity to AR S9346 further increases the likelihood of flares and the two regions could merge into a larger group. C1 flares: C1.9 @ 03:54, C1.5 @ 10:35, C1.8 @ 10:50, C1.6 @ 12:50, C1.9 @ 23:32 UT
Region 13560 [S10E21] lost some spots and was mostly quiet.
Region 13561 [S15W17] developed further and has polarity intermixing. C1 flares: C1.6 @ 20:57, C1.8 @ 21:33 UT
Region 13562 [S08W27] was mostly quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9338 [N17W30] was quiet and stable.
S9346 [N28E30] developed further and produced several C flares. The region was the source of an M1.5 flare at 06:22 UT on January 22. Further flaring is likely due to the proximity with AR 13559. C1 flares: C1.5 @ 08:21, C1.7 @ 09:18, C1.7 @ 10:13, C1.7 @ 15:15 UT
S9351 [S19W11] decayed slowly and quietly.
S9352 [S33W28] decayed slowly and quietly.
S9353 [N26W02] was quiet and stable.
New region S9356 [N14W71] emerged with a tiny spot.
New region S9357 [S17W14] emerged very close to AR 13561.
New region S9358 [N10E09] emerged with tiny spots.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C4.0 00:27   13559 GOES16 involved filaments southeast of the region. Partial halo CME
C5.3 00:41   13559 GOES16  
C4.8 01:38   13560 GOES16  
C6.3/1F 02:02   13559 GOES16  
C2.4 03:16   13559 GOES16  
C2.0 05:23   13559 GOES16  
C2.2 07:44 N25E30 13559 GOES16  
C2.0 08:40 N25E30 13559 GOES16  
C2.5 11:37 N29E36 S9346 GOES16  
C2.2 15:25   S9346 GOES16  
C2.9 16:23   13559 GOES16  
C2.8 17:02   13557 GOES16  
C3.9 17:34   13559 GOES16  
C5.8 18:38   13559 GOES16  
C7.1 18:42   13559 GOES16  
C2.7 19:28   13561 GOES16  
C6.7 19:35   13559 GOES16 SWPC attributed this to smaller, preceding flare in AR 13561
C5.8 20:15   S9346 GOES16  
C2.7 21:51   13559 GOES16  
C3.7 22:41   S9346 GOES16  

Coronal mass ejections (CMEs)

January 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.
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.

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 fair to good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be 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. Quiet to unsettled is expected for January 24.

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
1     S06W91 0120 HSX     rotated out of view
13551 2024.01.10
2024.01.12
      N26W64          

location: N27W62

13548 2024.01.10
2024.01.12
      N15W80           location: N12W75
13549 2024.01.10
2024.01.12
1 3 1 S21W55 0170 HSX CHO

area: 0320

location: S21W53

13553 2024.01.13
2024.01.13
1 7 4 N05W38 0020 HRX CRO location: N04W37
13554 2024.01.13
2024.01.15
      N07W31          

location: N07W26

S9324 2024.01.13       S19W24            
13555 2024.01.14
2024.01.15
5 12 5 S12W09 0110 CSO CSO

area: 0150

location: S12W12

S9327 2024.01.14       N12W54            
S9328 2024.01.14       N21W57            
S9329 2024.01.15       S19W11            
13556 2024.01.15
2024.01.16
1 7 3 N15W01 0070 HAX CSO  
13557 2024.01.16
2024.01.16
  7 2 S13E04 0015   AXX

location: S22E10

13561 2024.01.16
2024.01.19
8 33 19 S16W16 0090 DRI DAI beta-gamma

area: 0270

location: S17W14

S9333 2024.01.16       N11W16            
S9334 2024.01.16       N13W48            
13559 2024.01.17
2024.01.18
28 48 30 N27E22 0300 EKC EKI beta-gamma

area: 0760

location: N26E20

13560 2024.01.17
2024.01.18
10 21 13 S10E22 0060 CRI DRI

location: S10E21

area: 0090

S9337 2024.01.17       S19W42          
S9338 2024.01.17   3 1 N17W30 0005   BXO  
S9339 2024.01.17       N25W50            
S9340 2024.01.17       N11W27            
S9341 2024.01.18       S11W41            
S9342 2024.01.18       S10W16            
S9343 2024.01.18       N22E18            
S9344 2024.01.18       S02W35            
S9346 2024.01.19   18 8 N28E30 0070   DAI beta-gamma
S9347 2024.01.19       S23W26          
S9348 2024.01.19       N12W31          
13562 2024.01.20
2024.01.20
5 19 8 S08W27 0110 DAO DAO

area: 0180

S9351 2024.01.20   2 1 S19W11 0004   AXX  
S9352 2024.01.20   2   S33W28 0003   AXX  
S9353 2024.01.20   3 1 N26W02 0008   AXX  
S9354 2024.01.20       N11W56          
S9355 2024.01.20       N14E19          
S9356 2024.01.21   1 1 N14W71 0003   AXX    
S9357 2024.01.21   8 3 S17W14 0030   DRO    
S9358 2024.01.21   2 2 N10E09 0005   BXO    
Total spot count: 60 196 102  
Sunspot number: 150 366 262  (total spot count + 10 * number of spotted regions)
Weighted SN: 104 250 156  (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): 165 201 210  

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
2024.01 168.3 (1)   93.7 (2A) / 138.3 (2B) / 155.4 (2C) (117.9 projected, -3.3) (5.1)
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.