Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 16, 2024 at 05:45 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 on January 15. Solar wind speed at SOHO ranged between 309 and 376 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels.

Solar flux density measured at 20h UT on 2.8 GHz was 182.5 - increasing 3.2 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.87. 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: 5.0). Three hour interval K indices: 11222012 (planetary), 11222222 (Boulder), 20111034 (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 17 active regions using 2K resolution (SN: 309) and in 13 active regions using 1K resolution (SN: 188) SDO/HMI images.

Region 13540 [S19W66] produced low level C flares. The westernmost spots gained area. C1 flares: C1.7 @ 00:17, C1.7 @ 09:00, C1.4 @ 09:42, C1.3 @ 13:31, C1.2 @ 22:10 UT
Region 13541 [S23W59] decayed slowly producing a few low level C flares. C1 flares: C1.4 @ 03:26, C1.5 @ 03:45, C1.6 @ 05:23, C1.3 @ 06:41, C1.6 @ 07:28, C1.7 @ 16:52, C1.7 @ 17:10 UT
Region 13545 [S06W10] was mostly quiet and stable. C1 flares: C1.2 @ 23:49 UT
Region 13546 [S24W28] decayed slowly and quietly.
Region 13547 [N19W31] decayed slowly and lost the leader spots.
Region 13548 [N10E04] decayed slowly and quietly.
Region 13549 [S21E23] was mostly quiet and stable. C1 flares: C1.5 @ 12:01 UT
Region 13550 [S17W17] decayed slowly and quietly.
Region 13551 [N26E13] decayed slowly and quietly.
Region 13552 [S22W52] decayed slowly and quietly.
Region 13553 [N05E42] was mostly quiet and stable.
New region 13554 [N07E53] rotated into view on January 13 and was numbered 2 days later by SWPC.
New region 13555 [S11E71] rotated into view on January 14 and received its NOAA number the next day.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9303 [S11W49] was quiet and stable. C1 flares: C1.9 @ 19:33 UT
S9324 [S19E41] was quiet and stable.
New region S9329 [S19E68] emerged with tiny spots.
New region S9330 [N16E78] rotated into view with a mature spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.1 02:26   13541 GOES16  
C2.8 14:05   13553 GOES16  
C2.0 18:44   13541 GOES16  

Coronal mass ejections (CMEs)

January 13-15: 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 (CH1197) rotated across the central meridian on January 13. Another positive polarity northern hemisphere coronal hole (CH1198) will be 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. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to active on January 16-17 due to effects from CH1197. Quiet conditions are likely on January 18. January 19-21 could see quiet to active levels due to effects from CH1198.

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
13541 2024.01.04
2024.01.05
9 14 7 S20W61 0120 CAO CAO

area: 0090

location: S23W59

13540 2024.01.04
2024.01.05
8 15 10 S17W59 0160 CAI CAI location: S19W66

area: 0200

13544 2024.01.05
2024.01.07
      N18W52            
S9303 2024.01.06   8 3 S11W49 0015   BXO  
13545 2024.01.08
2024.01.09
10 17 10 S06W10 0290 CKO CKO area: 0410
13546 2024.01.08
2024.01.09
  5   S24W31 0010   BXO

location: S24W28

S9311 2024.01.09       N19W31            
13550 2024.01.09
2024.01.12
3 4   S18W17 0010 AXX BXO location: S17W17

area: 0006

13552 2024.01.09
2024.01.12
2 3 2 S22W53 0010 CAO BXO location: S22W52
13547 2024.01.10
2024.01.11
  3   N18W37 0005   AXX

location: N19W31

13551 2024.01.10
2024.01.12
  8 1 N26E11 0010   BXO

location: N26E13

13548 2024.01.10
2024.01.12
2 11 5 N12W00 0030 CAO BXO location: N10E04
13549 2024.01.10
2024.01.12
8 20 8 S17E23 0240 CSO CHO location: S21E23

area: 0350

S9319 2024.01.12       N35W07            
13553 2024.01.13
2024.01.13
3 9 3 N05E42 0150 HSX CAO area: 0180
S9321 2024.01.13       N11W20            
13554 2024.01.13
2024.01.15
2 6 2 N07E53 0070 HSX CAO area: 0100
S9324 2024.01.13   4   S19E41 0007   AXX  
13555 2024.01.14
2024.01.15
3 6 3 S11E72 0040 DAO EAO location: S11E71

area: 0230

S9326 2024.01.14       S10W16          
S9327 2024.01.14       N12E24          
S9328 2024.01.14       N21E21          
S9329 2024.01.15   5 3 S19E68 0015   BXO    
S9330 2024.01.15   1 1 N16E78 0140   HSX    
Total spot count: 50 139 58  
Sunspot number: 150 309 188  (total spot count + 10 * number of spotted regions)
Weighted SN: 100 189 108  (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): 165 170 150  

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  176.4 182.2 159.1 (124.6 projected, -0.4) 8.15
2023.08  153.7 157.6 114.8 (124.1 projected, -0.5) 7.19
2023.09  154.4 156.0 133.6 (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
2024.01 167.7 (1)   66.2 (2A) / 136.8 (2B) / 153.5 (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.

--------------------------------------------------------------------------------------

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.