Solar Terrestrial Activity Report

Activity chart

Last major update issued on January 30, 2024 at 07:00 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 29, weakly under the influence of effects from CH1199 or CH1200. Solar wind speed at SOHO ranged between 367 and 529 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux peaked at 137 pfu at 18:00 UT and decreased to below event level at 04:25 UT on January 30.

Solar flux density measured at 20h UT on 2.8 GHz was 140.3 - decreasing 1.8 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: 7.4). Three hour interval K indices: 32112222 (planetary), 21113322 (Boulder), 33102243 (Andenes).

The background x-ray flux is at the class B9 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 191) and in 9 active regions using 1K resolution (SN: 113) SDO/HMI images.

Region 13559 [N25W86] rotated partly out of view in a spectacular way with several C and M flares recorded.
Region 13563 [S07W10] decayed slowly and quietly.
Region 13565 [N05E52] still has a weak magnetic delta structure. Magnetic shear decreased as the opposite polarity umbrae drifted apart.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9346 [N28W73] produced a minor M class flare and was otherwise mostly quiet.
S9366 [N21E28] was mostly quiet and stable. C1 flares: C1.3 @ 21:04 UT
S9371 [S09E32] was mostly quiet and stable.
S9377 [S09W22] reemerged with tiny spots.
S9378 [S12W47] was quiet and stable.
S9381 [N18E73] has M class flare potential and is currently the largest region on the visible disk. C1 flares: C1.8 @ 22:32, C1.6 @ 23:21, C1.5  23:55 UT
S9382 [S13E19] was quiet and stable.
New region S9383 [S17W18] was observed with tiny spots in an old plage area.
New region S9384 [S35E16] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.5 00:39   S9381 GOES16  
C5.2 00:51   S9381 GOES16  
M1.2 01:40 N29W61 S9346 GOES16  
C2.5 02:58   S9381 GOES16 simultaneous flare in AR S9381
C2.5 03:51   13559 GOES16 simultaneous flare in AR S9381
M6.8 04:38 N25W70 13559 GOES16 moderate type II radio sweep, partial halo CME, proton flux above 10 MeV event, LDE
M2.5 05:39   13565 GOES16  
M1.0 06:43   13559 GOES16 simultaneous flares in ARs 13560 and S9381
C5.5 07:54     GOES16  
C3.1 09:41   S9381 GOES16  
C5.4 10:18   S9381 GOES16 weak type II radio sweep
C5.1 10:37   S9381 GOES16  
C2.5 11:06   13559 GOES16  
C2.3 11:33   S9381 GOES16  
C2.8 11:43   13565 GOES16  
C2.0 12:22   S9381 GOES16  
C2.0 12:45   13565 GOES16  
C2.0 13:24   13559 GOES16  
C2.0 14:41   13559 GOES16  
C6.0 14:56   13559 GOES16  
C2.4 15:31   13559 GOES16 simultaneous flare in AR S9381
C2.1 15:42   S9381 GOES16  
C5.9 16:42   13559 GOES16  
C2.2 17:52   13559 GOES18  

Coronal mass ejections (CMEs)

January 27-28: No obviously Earth directed CMEs were observed.
January 29: A partial halo CME was observed after the M6.8 flare in AR 13559 early in the day. While Earth is not in the path of the major part of the ejecta, there is a chance of a shock arrival on January 31.

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. A positive polarity southern hemisphere coronal hole (CH1201) could become Earth facing on February 1-2. CH1201 is probably too far south to cause a geomagnetic 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 30 due to effects from CH1199 and quiet to active on January 31-February 1 due to a possible shock arrival associated with the M6 flare in AR 13559 on January 29.

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
6 2   N26W83 0180 EAO CAO

location: N25W86

SWPC includes AR S9346

rotated mostly out of view

13560 2024.01.17
2024.01.18
8     S11W89 0050 CAI     rotated out of view
S9346 2024.01.19   1 1 N28W73 0020   HRX  
S9362 2024.01.23       S23W55            
S9364 2024.01.24       S10W32            
S9366 2024.01.25   8 2 N21E28 0014   AXX  
S9367 2024.01.25       N31W04            
S9368 2024.01.25       S26W24            
13563 2024.01.26
2024.01.26
  3   S05W10 0007   AXX location: S07W10
S9369 2024.01.26       N24W39            
S9370 2024.01.26       N15E01            
S9371 2024.01.26   7 2 S09E32 0015   BXO  
S9372 2024.01.26       N24W54            
S9373 2024.01.26       N11W50            
S9374 2024.01.26       N07W37          
S9375 2024.01.26       S21E01            
S9377 2024.01.27   3 1 S09W22 0006   AXX    
S9378 2024.01.27   5 3 S12W47 0016   CRO  
S9379 2024.01.27       N31W05          
13565 2024.01.27
2024.01.28
4 15 5 N08E50 0030 CRO DRI beta-delta

location: N05E52

area: 0050

13564 2024.01.28       S09E40            
S9381 2024.01.28   16 6 N18E71 0440   DKI  
S9382 2024.01.28   4 2 S13E19 0020   CRO  
S9383 2024.01.29   6   S17W18 0010   BXO    
S9384 2024.01.29   1 1 S35E16 0003   AXX    
Total spot count: 18 71 23  
Sunspot number: 48 191 113  (total spot count + 10 * number of spotted regions)
Weighted SN: 31 98 50  (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): 53 105 90  

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
2024.01 166.5 (1)   117.6 (2A) / 125.8 (2B) / 159.8 (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.