Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 20, 2024 at 11:55 UT. Minor update added at 12:45 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 19 under the influence of weak effects from CH1197. Solar wind speed at SOHO ranged between 379 and 454 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 157.4 - decreasing 16.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.28. 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: 13212212 (planetary), 12212212 (Boulder), 33221325 (Andenes).

The background x-ray flux is at the class B5 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 18 active regions using 2K resolution (SN: 333) and in 15 active regions using 1K resolution (SN: 229) SDO/HMI images.

Region 13545 [S06W64] was quiet and stable.
Region 13549 [S20W27] was mostly quiet and stable. C1 flares: C1.4 @ 15:16 UT
Region 13551 [N27W36] was quiet and stable.
Region 13553 [N05W11] decayed further and was mostly quiet. C1 flares: C1.0 @ 03:03, C1.3 @ 04:56 UT
Region 13554 [N07W00] decayed slowly and quietly.
Region 13555 [S11E16] was mostly quiet and stable.
Region 13556 [N16E39] was quiet and stable.
Region 13557 [S24E42] was quiet and stable.
Region 13559 [N27E47] was mostly quiet and stable. C1 flares: C1.0 @ 09:37 UT
Region 13560 [S09E48] developed as new flux emerged in the trailing spot section.
New region 13561 [S15E09] developed on January 16 with tiny spots and gained spots and area on January 18/19 when new flux emerged.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9337 [S17W15] was quiet and stable.
S9338 [N19W05] was quiet and stable.
S9339 [N25W24] was quiet and stable.
S9342 [S10E10] was quiet and stable.
New region S9346 [N29E59] emerged to the east of AR 13559.
New region S9347 [S23W02] was observed with tiny spots in an old plage area.
New region S9348 [N12W04] emerged with tiny spots.

AR 13558 behind the southwest limb was the source of a C1.8 flare at 01:53 and a C1.4 flare at 11:37 UT

Minor update added at 12:45 UT: AR 13555 was the source of a long duration C3.5 event peaking at 09:35 UT on January 20. A full halo CME was observed beginning at 09:24 UT in LASCO C2 imagery. This CME could reach Earth on January 23.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.4 13:25 behind southwest limb 13558 GOES16  

Coronal mass ejections (CMEs)

January 17-19: No obviously Earth directed CME 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 positive polarity northern hemisphere coronal hole (CH1198) was Earth facing on January 16-18.

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 to unsettled on January 20-21 due to effects from CH1198 and quiet on January 22-23.

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
2 2 2 S06W66 0180 HAX HKX area: 0400

location: S05W64

13546 2024.01.08
2024.01.09
      S24W87          

location: S23W69

13550 2024.01.09
2024.01.12
      S18W73           location: S18W55
13551 2024.01.10
2024.01.12
3 5 4 N26W36 0020 BXO CRO

location: N27W36

13548 2024.01.10
2024.01.12
      N15W52           location: N12W49
13549 2024.01.10
2024.01.12
3 14 8 S21W28 0200 CAO CHO

area: 0350

location: S20W27

S9319 2024.01.12       N35W59            
13553 2024.01.13
2024.01.13
6 11 6 N05W11 0110 CAO CAO  
S9321 2024.01.13       N11W59            
13554 2024.01.13
2024.01.15
2 8 3 N07W01 0010 AXX BXO

location: N07W00

S9324 2024.01.13       S19E02            
13555 2024.01.14
2024.01.15
8 22 13 S11E16 0150 DAI DSI

area: 0220

S9327 2024.01.14       N12W28            
S9328 2024.01.14       N21W31            
S9329 2024.01.15       S19E15          
13556 2024.01.15
2024.01.16
2 7 3 N16E25 0090 HAX HSX

area: 0110

13557 2024.01.16
2024.01.16
  3   S13E32 0003   BXO

location: S24E42

13561 2024.01.16
2024.01.19
4 15 11 S16E11 0020 CAO DRI location: S15E09
S9333 2024.01.16       N11E10            
S9334 2024.01.16       N13W22            
13559 2024.01.17
2024.01.18
6 19 10 N26E46 0170 DAO EAI area: 0300
13560 2024.01.17
2024.01.18
1 16 10 S11E52 0010 AXX DRI beta-gamma

location: S09E48

area: 0035

S9337 2024.01.17   7   S17W15 0015   AXX  
S9338 2024.01.17   8 2 N19W05 0015   AXX  
S9339 2024.01.17   5 2 N25W24 0010   AXX  
S9340 2024.01.17       N11W01            
S9341 2024.01.18       S11W15          
S9342 2024.01.18   3 1 S10E10 0005   BXO  
S9343 2024.01.18       N22E44          
S9344 2024.01.18       S02W09          
S9346 2024.01.19   1 1 N29E59 0010   HRX    
S9347 2024.01.19   5 3 S23W02 0012   BXO    
S9348 2024.01.19   2   N12W04 0002   BXO    
Total spot count: 37 153 79  
Sunspot number: 137 333 229  (total spot count + 10 * number of spotted regions)
Weighted SN: 72 205 131  (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): 151 183 183  

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
2024.01 167.9 (1)   84.2 (2A) / 137.4 (2B) / 153.0 (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.