Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 6, 2024 at 06:00 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 (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 5, weakly under the influence of effects from CH1201. Solar wind speed at SOHO ranged between 360 and 510 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm 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 173.4 - decreasing 2.3 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.27. 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: 5.4). Three hour interval K indices: 01112222 (planetary), 00112322 (Boulder), 00000125 (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 15 active regions using 2K resolution (SN: 317) and in 14 active regions using 1K resolution (SN: 225) SDO/HMI images.

Region 13565 [N05W42] decayed slowly and was mostly quiet.
Region 13567 [N18W19] was quiet and stable.
Region 13570 [S05W04] was quiet and stable.
Region 13571 [S17E10] was quiet and stable.
Region 13572 [S12W32] was quiet and stable.
Region 13573 [N21W46] decayed slowly and quietly.
Region 13574 [N16E21] was quiet and stable. The region has reversed polarities.
Region 13575 [S37W62] decayed and lost area. 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. An M4.2 long duration event peaked at 03:11 UT on February 6.
Region 13576 [S15E57] continued to be very active. The region has a magnetic delta structure in the largest penumbra, and some polarity intermixing otherwise. A major flare is possible.
New region 13577 [N24E22] was first observed with spots on February 2 and was numbered by SWPC 3 days later when new flux emerged.
New region 13578 [S04E68] rotated into view on February 4 with SWPC numbering the spot group the next day. The region has reversed polarities.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9394 [N21W52] reemerged with tiny spots.
S9401 [S22E19] was quiet and stable.
New region S9404 [S13W49] emerged with a few spots.
New region S9405 [N39E57] emerged with tiny spots at a high latitude and has the potential to develop further.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.2 01:55   13576 GOES16  
C3.9 02:17   13576 GOES16  
C3.1 02:37   13576 GOES16  
C4.0 03:22   13576 GOES16  
C8.8 03:29 S16E71 13576 GOES16  
M2.1 04:28 S16E71 13576 GOES16  
M1.4 04:38   13576 GOES16  
C4.0 05:39   13575 GOES16 simultaneous flare in AR 13576
M1.4 06:22 S21E79 13576 GOES16  
C3.7 06:31   13576 GOES16  
C4.6 07:43 S38W51 13575 GOES16  
C6.9 08:02   13575 GOES16  
C2.7 09:19   13576 GOES16  
C2.8 10:13   13576 GOES16  
C9.6 11:09 S15E71 13576 GOES16  
C2.9 11:41   13576 GOES16  
C3.9 12:29   13576 GOES16  
C2.6 12:46   13576 GOES16  
C6.3 13:19 S15E68 13576 GOES16  
C3.8 13:40   13576 GOES16  
C3.6 14:19   13576 GOES16  
C3.3 15:02   13576 GOES16  
C2.9 16:18   13575 GOES16 simultaneous flare in AR 13576
C2.4 16:30   13575 GOES16  
C2.2 17:00   13576 GOES16  
C3.8 17:26 S35W53 13575 GOES16  
C2.3 18:18   13576 GOES16  
C2.2 19:07   13576 GOES16  
C2.2 19:34   13576 GOES16  
C2.6 21:57   S9404 GOES16 simultaneous flare in AR 13576
C2.2 22:42   13576 GOES16  
C6.1/1F 23:11 N10W40 13565 GOES16  

Coronal mass ejections (CMEs)

February 3-5: No obviously Earth directed CMEs were observed.
February 6: A long duration M4.2 event peaking at 03:11 UT had its source in AR 13575. A shock wave affected the corona far from the source. A partial halo CME was associated with this event, maybe even a very faint full halo CME. The CME was visible in LASCO C2 imagery from 02:36 UT.

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 poor. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to unsettled on February 6 due to effects from CH1201. Quiet conditions are likely on February 7-8. The February 6 CME, if it reaches Earth, could cause a disturbance on February 8-9.

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 10 6 N06W43 0010 BXO DRI

area: 0040

location: N05W42

13564 2024.01.28       S14W59            
13567 2024.01.28
2024.01.30
4 16 7 N16W21 0010 BXO BXO

area: 0030

location: N18W19

13569 2024.01.28       S12W81           location: S13W74
13570 2024.01.30
2024.02.01
2 8 4 S05W07 0010 BXO DRO

area: 0030

location: S05W04

13572 2024.01.31
2024.02.01
1 5 2 S12W34 0005 AXX BXO location: S12W32

area: 0013

13571 2024.01.31
2024.02.01
3 6 4 S17E08 0100 HSX HSX

area: 0180

13575 2024.01.31
2024.02.02
7 23 9 S36W64 0270 DKC DKC beta-gamma-delta

reversed polarities

location: S37W62

area: 0340

13573 2024.02.01
2024.02.01
2 3 2 N22W46 0010 BXO AXX

location: N21W46

13574 2024.02.01
2024.02.01
2 8 6 N16E17 0030 CAO DAO

area: 0060

location: N16E21

reversed polarities

S9394 2024.02.01   2   N21W52 0003   BXO    
S9395 2024.02.01       N26W32          
13577 2024.02.02
2024.02.05
3 11 7 N25E20 0005 BXO DRI area: 0040
13576 2024.02.03
2024.02.03
13 54 30 S15E57 0610 EKC FKC beta-gamma-delta

area: 1160

S9400 2024.02.03       N14W33          
S9401 2024.02.04   6 2 S22E19 0013   BXO  
13578 2024.02.04
2024.02.05
1 6 3 S03E67 0005 AXX CRO location: S04E68

area: 0025

reversed polarities

S9403 2024.02.04       S07E04          
S9404 2024.02.05   7 2 S13W49 0030   DRO    
S9405 2024.02.05   2 1 N39E57 0007   AXX    
Total spot count: 42 167 85  
Sunspot number: 152 317 225  (total spot count + 10 * number of spotted regions)
Weighted SN: 72 212 130  (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): 167 174 180  

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
2024.02 155.9 (1)   22.7 (2A) / 131.4 (2B) / 166.1 (2C) (116.3 projected, -0.8) (3.8)
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.