Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 9, 2024 at 09:55 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 on February 8. Solar wind speed at SOHO ranged between 428 and 535 km/sec. The high latitude magnetometer at Andenes recorded quiet 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 185.0 - decreasing 1.4 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.31. 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 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.5). Three hour interval K indices: 11122220 (planetary), 11112311 (Boulder), 00101220 (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 15 active regions using 2K resolution (SN: 307) and in 12 active regions using 1K resolution (SN: 209) SDO/HMI images.

Region 13567 [N20W53] was quiet and stable. SWPC has added new region AR 13480 for this spot group, keeping the old group number in order to maintain data integrity.
Region 13571 [S17W29] decayed slowly and quietly.
Region 13572 [S12W72] developed slowly and quietly.
Region 13574 [N17W19] decayed slowly and was mostly quiet. The region has reversed polarities.
Region 13576 [S15E17] has a very large elongated leader penumbra with many umbrae and a significant magnetic delta structure in the eastern part. The spot group produced many M and C flares. A major flare is possible. C1 flares: C1.8 @ 00:48, C1.9 @ 03:43, C1.9 @ 05:55, C1.6 @ 08:09, C1.7 @ 09:27 UT
Region 13577 [N24W15] decayed slowly and quietly.
Region 13578 [S04E27] decayed slowly and was mostly quiet. The region has reversed polarities.
New region 13579 [S10E32] emerged on February 6 and decayed slowly on February 8. SWPC numbered the region on February 7, however, with a location far from the actual location.
New region 13581 [S21E71] rotated into view on February 7 and was numbered by SWPC the next day.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9401 [S23W18] was quiet and stable.
S9404 [S14W86] rotated partly out of view and produced several flares.
S9406 [N15E48] reemerged with tiny spots.
New region S9411 [S12W13] was observed with tiny spots in an old plage area.
New region S9412 [N08E42] emerged with a tiny spot.
New region S9413 [N09E68] rotated into view with tiny spots.

AR 13565 behind the southwest limb produced an X3.5 flare peaking at 13:14 UT on February 9.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.5 01:12   13576 GOES16  
C3.9 01:37   13574 GOES16  
C2.5 02:50   13575 GOES16  
C2.2 04:14   13576 GOES16  
C2.2 04:40   13576 GOES16  
C2.7 04:50   13576 GOES16  
C2.4 05:17   13576 GOES16  
C4.4 08:48 S16E27 13576 GOES16  
C2.2 09:40   13576 GOES16 simultaneous flare in AR 13567
C2.2 10:42   13576 GOES16  
C3.4 11:06   13576 GOES16  
C5.3 11:40   13576 GOES16  
C9.8/2B 11:46   13576 GOES16 moderate type II radio sweep
C4.9 12:23   13576 GOES16  
M3.4 13:12   13576 GOES16 LDE
M1.2 14:18   S9404 GOES16  
C6.5 14:38   13576 GOES16  
C5.1 14:57   13576 GOES16  
M1.8/1F 15:23   13576 GOES16  
C6.1 16:21 S11W81 S9404 GOES16  
C7.0 17:07   13576 GOES16  
C2.8 17:21   13576 GOES16  
C2.1 17:53   13576 GOES16  
C2.7 18:03 S15E24 13576 GOES16  
M1.3/1F 19:02   13576 GOES16  
C7.5 19:10   13576 GOES16  
C3.4 19:40   S9404 GOES16  
C3.3 20:09   13576 GOES16  
C3.4 20:18   13576 GOES16  
C2.5 20:54   13576 GOES18  
C2.7 22:21 S15E23 13576 GOES16  
C2.8 22:33   13576 GOES16  
M3.9 23:55   13575 GOES16  

Coronal mass ejections (CMEs)

February 7-8: 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 away 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 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 fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to unsettled on February 9-10 due to weak CME effects. Quiet conditions are likely on February 11, however there is some uncertainty as there were many CMEs on February, although none of them clearly Earth directed.

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
      N05W83            
13567 2024.01.28
2024.01.30
  7 3 N17W63 0025   CRO

location: N20W53

13570 2024.01.30
2024.02.01
      S03W50        

location: S02W45

13572 2024.01.31
2024.02.01
1 5 4 S12W74 0020 HSX CRO

location: S12W72

13571 2024.01.31
2024.02.01
2 6 5 S19W28 0080 HAX HSX

area: 0120

location: S17W29

13573 2024.02.01
2024.02.01
      N21W89          

location: N21W85

13574 2024.02.01
2024.02.01
2 7 3 N16W22 0020 HSX CRO

area: 0025

location: N17W19

reversed polarities

13577 2024.02.02
2024.02.05
1 7 1 N25W18 0010 HSX BXO

location: N24W15

13576 2024.02.03
2024.02.03
44 87 56 S16E17 0670 FKC FKC beta-gamma-delta

area: 0920

location: S15E17

S9401 2024.02.04   10 5 S23W18 0016   BXO  
13578 2024.02.04
2024.02.05
3 12 4 S04E26 0020 CSO CRO

reversed polarities

S9403 2024.02.04       S07W35            
S9404 2024.02.05   2 1 S14W86 0006   HAX  
S9405 2024.02.05       N39E20            
S9406 2024.02.06   3   N15E48 0003   BXO    
13579 2024.02.06
2024.02.07
3 8 5 S12E37 0030 CRO CRO location: S10E32
13581 2024.02.07
2024.02.08
1 2 1 S20E68 0060 HSX HSX location: S21E71

area: 0190

13580 2024.02.08 2     N23W50 0030 HAX       see AR 13567
S9411 2024.02.08   8   S14W13 0015   BXO    
S9412 2024.02.08   1 1 N08E42 0003   AXX    
S9413 2024.02.08   2   N09E68 0003   AXX    
Total spot count: 59 167 89  
Sunspot number: 149 307 209  (total spot count + 10 * number of spotted regions)
Weighted SN: 107 207 129  (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): 164 169 167  

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
2024.02 166.5(1)   39.8 (2A) / 144.4 (2B) / 166.3 (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.