Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 5, 2024 at 06:20 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 (February 4, 2024)
Solar cycle Solar cycles 23-25 (February 1, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (February 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 (February 1, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (February 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 February 4, weakly under the influence of effects from CH1201 after 10h UT. Solar wind speed at SOHO ranged between 301 and 446 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux was at background levels at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 170.4 - decreasing 5.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.19. 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 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.9). Three hour interval K indices: 11121123 (planetary), 01111233 (Boulder), 32000044 (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 16 active regions using 2K resolution (SN: 313) and in 13 active regions using 1K resolution (SN: 208) SDO/HMI images.

Region 13565 [N05W28] was quiet and stable.
Region 13567 [N18W05] decayed slowly and was mostly quiet.
Region 13570 [S04E08] decayed slowly and quietly.
Region 13571 [S17E23] decayed slowly and quietly.
Region 13572 [S12W15] was quiet and stable.
Region 13573 [N21W31] was quiet and stable.
Region 13574 [N16E35] decayed slowly and quietly.
Region 13575 [S37W49] lost some umbral area, however, it is still a compact and complex spot group. The region produced only a few flares during the day. The region has reversed polarities and could produce M and possibly X flares.
Region 13576 [S15E69] is a large, complex spot group with major flare potential. The region was by far the most active on the visible disk.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9371 [S08W48] decayed slowly and quietly.
S9395 [N26W19] was quiet and stable.
S9398 [N24E34] reemerged with tiny spots.
S9400 [N14W20] was quiet and stable.
New region S9401 [S22E35] was observed with tiny spots in an old plage area.
New region S9402 [S04E80] rotated into view with a small spot.
New region S9403 [S07E17] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.9 00:20   13576 GOES16  
C3.3 00:30   13576 GOES16  
C2.7 00:50   13576 GOES16  
C3.6 01:17   13576 GOES16  
C3.8 01:39   13576 GOES16  
C3.3 02:27   13576 GOES16  
C3.9 02:53   13576 GOES16  
C3.5 04:01   13576 GOES16  
C3.7 04:39   13575 GOES16  
C2.5 05:59   13576 GOES16  
C3.7 07:01   13576 GOES16  
C3.9 07:16   13576 GOES16  
C4.8 07:34   13576 GOES16  
C4.3 07:40   13576 GOES16  
C3.9 08:21   13576 GOES16  
C3.0 08:54   13575 GOES16  
C3.1 09:21   13576 GOES16  
C2.6 09:36   13576 GOES16  
M1.4 11:52 S15E86 13576 GOES16  
C8.4 13:46 S15E75 13576 GOES16  
C2.7 14:26   13576 GOES16  
C2.6 14:34   13576 GOES16  
C4.3 15:16 S22E84 13576 GOES16  
C3.4 15:25   13576 GOES16  
C6.0 15:57 S15E74 13576 GOES16  
C5.6 16:13   13576 GOES16  
M1.5 16:38 S15E73 13576 GOES16  
M1.3 17:12 S15E73 13576 GOES16  
C3.9 17:37   13576 GOES16  
M1.1 18:29 S17E75 13576 GOES16  
C9.6 18:36   13575 GOES16  
C3.7 19:19   13575 GOES16  
C3.6 20:13   13575 GOES16  
C4.4 20:19   13576 GOES16  
M1.2 20:57 S22E79 13576 GOES16  
C4.7 21:10 S17E75 13576 GOES16  
C5.5 22:02   S9402 GOES16  
M2.1 22:28   13576 GOES16  
M2.7 22:37 S13E90 13576? GOES16 multiple flare centers
C7.6 23:15   13576 GOES16  
C4.8 23:38   13576 GOES16  

Coronal mass ejections (CMEs)

February 2-4: No obviously Earth directed CMEs were 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 southern hemisphere coronal hole (CH1201) was Earth facing on February 1-2.

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 unsettled on February 5 due to effects from CH1201. Quiet conditions are likely on February 6-7.

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
S9366 2024.01.25       N21W50          
S9371 2024.01.26   4   S08W48 0006   BXO  
13565 2024.01.27
2024.01.28
8 23 12 N05W29 0020 CRO CRI

area: 0030

13564 2024.01.28       S14W45            
13567 2024.01.28
2024.01.30
8 14 5 N18W06 0030 CRI ERO

area: 0040

location: N18W05

13569 2024.01.28       S12W66           location: S13W61
13570 2024.01.30
2024.02.01
4 5 3 S05E08 0020 DRO DRO

area: 0030

location: S04E08

13572 2024.01.31
2024.02.01
  2 1 S12W20 0005   BXO location: S12W15
13571 2024.01.31
2024.02.01
3 12 5 S17E23 0130 CSO CSO

area: 0220

13575 2024.01.31
2024.02.02
12 32 23 S37W51 0350 DKC DKC beta-gamma-delta

reversed polarities

location: S37W49

area: 0480

13573 2024.02.01
2024.02.01
2 5 3 N22W32 0010 CRO CRO

location: N21W31

13574 2024.02.01
2024.02.01
3 4 2 N16E32 0060 CSO CAO

area: 0110

location: N16E35

reversed polarities

S9394 2024.02.01       N23W35            
S9395 2024.02.01   1   N26W19 0001   AXX  
S9396 2024.02.01       S14W53            
S9398 2024.02.02   3 1 N24E34 0010   BXO    
13576 2024.02.03
2024.02.03
18 31 17 S16E72 0700 EKC EKC beta-delta

location: S15E69

area: 1130

S9400 2024.02.03   10 3 N14W20 0020   BXO  
S9401 2024.02.04   5 2 S22E35 0010   BXO    
S9402 2024.02.04   1 1 S04E80 0020   HRX    
S9403 2024.02.04   1   S07E17 0003   AXX    
Total spot count: 58 153 78  
Sunspot number: 138 313 208  (total spot count + 10 * number of spotted regions)
Weighted SN: 100 198 123  (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): 152 172 166  

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
2022.06 116.1 119.8 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)
2023.03 157.2 155.6 123.3 121.1 (+3.3) 14.42
2023.04 145.4 146.4 97.6 122.9 (+1.8) 13.40
2023.05 155.6 159.2 137.4 124.1 (+1.2) 10.67
2023.06 161.7 166.8 160.5 125.2 (+1.1)
(SC25 solar max candidate)
8.95
2023.07  176.4 182.2 160.0 124.3 (-0.9) 8.15
2023.08  153.7 157.6 114.8 (123.4 projected, -0.9) 7.19
2023.09  154.4 156.0 134.2 (123.1 projected, -0.3) 14.26
2023.10  142.8 141.9 99.4 (123.9 projected, +0.8) 8.16
2023.11 153.5 150.2 105.4 (123.9 projected, +0.0) 12.20
2023.12 151.1 146.4 114.2 (120.5 projected, -3.4) 9.60
2024.01 164.5 159.3 123.0 (117.1 projected, -3.3) 5.6
2024.02 151.6 (1)   17.4 (2A) / 126.3 (2B) / 165.7 (2C) (116.3 projected, -0.8) (3.4)
2024.03       (115.8 projected, -0.5)  
2024.04       (115.7 projected, -0.1)  
2024.05       (117.0 projected, +1.3)  
2024.06       (116.2 projected, -0.8)  
2024.07       (114.5 projected, -1.7)  

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.