Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 7, 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 (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 6, weakly under the influence of effects from CH1201. Solar wind speed at SOHO ranged between 449 and 571 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at 0.3 pfu, just above background levels, at the end of the day.

Solar flux density measured at 18h UT on 2.8 GHz was 179.0 - decreasing 7.0 over the previous solar rotation (The measurement at 20h UT was flare enhanced from a long duration M1 event that peaked at 18:49 UT). (Centered 1 year average SF at 1 AU - 183 days ago: 157.33. 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: 6.9). Three hour interval K indices: 32122121 (planetary), 21222221 (Boulder), 52111230 (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 19 active regions using 2K resolution (SN: 364) and in 17 active regions using 1K resolution (SN: 250) SDO/HMI images.

Region 13565 [N05W55] decayed slowly and quietly.
Region 13567 [N20W39] decayed slowly and quietly.
Region 13570 [S04W18] was quiet and stable.
Region 13571 [S17W03] decayed slowly and quietly.
Region 13572 [S12W47] developed slowly and was quiet.
Region 13573 [N21W59] decayed slowly and quietly.
Region 13574 [N16E08] decayed slowly and quietly. The region has reversed polarities.
Region 13575 [S37W73] decayed in the leading spot section. This is still a compact and complex spot group with a strong magnetic delta in the trailing spot section. The region has reversed polarities and could produce M and possibly X flares. A major M5.1 long duration event peaked at 03:33 UT on February 7. C1 flares: C1.9 @ 23:47 UT
Region 13576 [S15E43] was less active than on previous days as the magnetic delta structure weakened. A major flare is possible.
Region 13577 [N24E08] decayed slowly and quietly.
Region 13578 [S05E54] developed slowly and was mostly quiet. The region has reversed polarities. Minor polarity intermixing developed in the southern part of the spot group.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9394 [N22W64] was quiet and stable.
S9400 [N13W53] reemerged with tiny spots.
S9401 [S22E09] was quiet and stable.
S9404 [S13W62] developed slowly and quietly.
S9405 [N39E46] was quiet and stable.
New region S9406 [N12E71] rotated into view with tiny spots.
New region S9407 [S13W43] emerged with tiny spots.
New region S9408 [S10E62] emerged with tiny spots.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.2 00:40   13570? GOES16  
M2.2 02:28   13575 GOES16  
M4.2 03:11   13575 GOES16 LDE, minor proton enhancement
moderate type II and IV radio sweep
M1.0 05:03   13576 GOES16  
C6.8 06:06   13576 GOES16 simultaneous flare in AR S9404
C6.4 06:56     GOES16  
C3.8 09:05   13576 GOES16  
C4.2 09:33   13576 GOES16  
C2.8 10:43   13576 GOES16  
C2.6 11:26   13576 GOES16  
C4.5 11:45   13576 GOES16  
C4.1 12:14   13576 GOES16  
C9.4 12:58   13575 GOES16  
C3.1 13:47   13576 GOES16  
C2.5 14:04   13576 GOES16  
C2.6 15:32   13576 GOES16  
C3.9 16:08   13578 GOES16  
C5.1 16:14   13576 GOES16  
C3.0 16:51   13576 GOES16  
C3.2 17:44   13575 GOES16  
C2.6 18:15   13575 GOES16  
C6.2 18:35   13575 GOES16  
M1.3 18:49   13575 GOES16 LDE, flare still bright in EUV at 20:35 UT
C7.4 19:27   13575 GOES16 different flare center than M1.3 flare
C2.5 21:47   13575 GOES16  
C2.7 21:56   13576 GOES16  
C2.3 22:12   13578 GOES16  
C2.0 22:32   13575 GOES16  

Coronal mass ejections (CMEs)

February 3-5: No obviously Earth directed CMEs were observed.
February 6: A partial halo CME was observed after an M2.2 flare and a long duration M4.2 event peaking at 03:11 UT in AR 13575. A shock wave affected the corona far from the source. A partial halo CME was associated with this event. The CME was visible in LASCO C2 imagery from 02:36 UT. While the bulk of the CME is not headed for Earth, there is a chance of a weak solar wind shock on February 8 or 9. A nearly symmetrical full halo CME was observed near noon. While there was a large filament eruption in the northern hemisphere that was suspected as the origin, any CME associated with that event would be unlikely to cause a CME with the observed mass distribution and intensity. The source of the CME is thus likely to have been backsided.

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]

No obvious coronal holes are currently in or near Earth facing positions.

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 February 7 and most of February 8. During the latter half of February 8 or on February 9 there is a chance of weak CME effects associated with long duration events in AR 13575 early on February 6.

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
13565 2024.01.27
2024.01.28
4 5 3 N06W43 0010 BXO DRI

area: 0040

location: N05W42

13564 2024.01.28 3     S13W72 0030 CAO       SWPC has apparently included the spots of AR S9404 in this region, despite AR S9404 being 10 degrees further east.
13567 2024.01.28
2024.01.30
  5 1 N17W35 0010   AXX

location: N20W29

13570 2024.01.30
2024.02.01
  2   S05W20 0003   BXO

location: S04W18

13572 2024.01.31
2024.02.01
2 6 3 S12W48 0010 BXO DRO location: S12W47

area: 0025

13571 2024.01.31
2024.02.01
5 10 4 S17W05 0110 HSX CAO

area: 0160

location: S17W03

13575 2024.01.31
2024.02.02
7 9 4 S36W78 0250 DKI DKC beta-gamma-delta

reversed polarities

location: S37W73

area: 0290

13573 2024.02.01
2024.02.01
2 1 1 N21W61 0010 BXO AXX

location: N21W59

area: 0003

13574 2024.02.01
2024.02.01
3 5 3 N17E03 0030 CSO CRO

area: 0040

location: N16E08

reversed polarities

S9394 2024.02.01   3 2 N22W64 0008   BXO  
S9395 2024.02.01       N26W45            
13577 2024.02.02
2024.02.05
4 11 4 N24E06 0010 BXO DRO area: 0025

location: N24E08

13576 2024.02.03
2024.02.03
41 72 40 S16E46 0540 FKI FKC beta-gamma-delta

area: 0930

location: S15E43

S9400 2024.02.03   2 1 N13W53 0005   AXX    
S9401 2024.02.04   7   S22E09 0011   BXO  
13578 2024.02.04
2024.02.05
3 14 5 S05E53 0020 CRO CRO beta-gamma

location: S05E54

area: 0035

reversed polarities

S9403 2024.02.04       S07W09            
S9404 2024.02.05   10 4 S13W62 0120   CAO  
S9405 2024.02.05   2 1 N39E46 0004   BXO  
S9406 2024.02.06   2 1 N12E71 0005   AXX    
S9407 2024.02.06   4 2 S17W43 0020   CRO    
S9408 2024.02.06   4 1 S10E62 0010   CRO    
Total spot count: 74 174 80  
Sunspot number: 152 364 250  (total spot count + 10 * number of spotted regions)
Weighted SN: 72 225 131  (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): 167 200 200  

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
2024.01 164.6 159.3 123.0 (117.1 projected, -3.3) 5.46
2024.02 159.8 (1)   29.0 (2A) / 140.3 (2B) / 166.6 (2C) (116.3 projected, -0.8) (4.3)
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.