Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 15, 2024 at 04:30 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 14. Solar wind speed at SOHO ranged between 353 and 495 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels. The above 10 MeV proton flux was at 7 pfu at the end of the day, peaking at 47 pfu at 10:30 UT, probably influence by a large backsided flare from long departed AR 13565 just after 04h UT.

Solar flux density measured at 20h UT on 2.8 GHz was 184.1 - increasing 18.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.16. 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: 5.6). Three hour interval K indices: 33111001 (planetary), 23111212 (Boulder), 54110000 (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 10 active regions using 2K resolution (SN: 213) and in 10 active regions using 1K resolution (SN: 165) SDO/HMI images.

Region 13576 [S16W65] lost spots and still has 2 magnetic delta structures. A major flare is possible. C1 flares: C1.9 @ 00:23 UT
Region 13581 [S21W06] decayed slowly and quietly.
Region 13582 [N04W41] decayed slowly and was mostly quiet.
Region 13583 [N09W12] decayed slowly and was mostly quiet. C1 flares: C1.7 @ 05:52 UT
Region 13584 [S14E19] produced a few C flares and decayed slowly.
Region 13585 [N13E48] decayed slowly and was mostly quiet.
New region 13586 [N26E79] rotated fully into view with a mature spot.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9418 [N09W34] decayed slowly and was mostly quiet.
S9423 [S22E52] developed slowly and quietly.
New region S9425 [S02E44] emerged near the equator with a few spots.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.5 00:58 unnumbered region north of AR S9423   GOES16  
C2.6 01:07   13576 GOES16  
C2.2 01:41   13576 GOES16  
C2.5 02:11   13583 GOES16  
M1.0 03:10   S9418 GOES16  
C2.1 04:28   13576 GOES16  
C2.5 06:10   13582 GOES16  
C3.0 06:26   13582 GOES16 incorrectly attributed to AR 13584 by SWPC
C3.6 06:54   13576 GOES16  
M1.0 07:35   13576 GOES16  
C2.4 08:10   13571 GOES16 simultaneous flare in AR 13585
C2.4 08:44   13584 GOES16  
C2.6 09:26   13576 GOES16  
C2.0 09:46   13583 GOES16  
C4.6 10:06   13576 GOES16  
C2.8 10:29   13576 GOES16  
C2.3 11:04   13576 GOES16  
C2.9 11:28   13576 GOES16 simultaneous flare in AR 13583
C3.4 11:36   13576 GOES16  
C2.0 12:00   13584 GOES16  
C2.0 12:06   13576 GOES16  
C2.4 12:32   13576 GOES16  
C2.0 12:54   13576 GOES16  
C2.0 13:27   13576 GOES16  
C2.0 14:23   13576 GOES16 incorrectly attributed to AR 13584 by SWPC
C3.8 14:31   13576 GOES16 incorrectly attributed to AR 13584 by SWPC
C2.6 14:54   13576 GOES16  
C3.4 15:19   13576 GOES16  
C3.0 16:07   13576 GOES16 simultaneous flare in AR 13586
C4.7 17:10   13576 GOES16  
C7.5 17:56   13576 GOES16  
C2.1 18:52   13576 GOES16  
C2.1 19:54   13576 GOES16  
C2.5 20:28   13576 GOES16  
C2.3 21:47   13576 GOES16  
C2.3 22:30   13576 GOES16  
C5.3 22:40   13576 GOES16  
C2.2 23:27   13576 GOES16  

Coronal mass ejections (CMEs)

February 13-14: No obviously Earth directed CMEs were observed.
February 12: A backsided fast and large full halo CME was observed from 06:36 UT after a proton flare well behind the southwest limb from AR 13565. A well defined backsided CME was observed from 15:06 UT in LASCO C3 imagery following activity behind the northeast limb. Another backsided CME observed after 22h UT in LASCO C3 imagery was associated with a long duration M2.6 event peaking at 21:17 UT from a source behind the east limb.

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 small coronal hole in the southern hemisphere developed on February 14 and will be Earth facing on February 15.

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 on February 15-17.

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
13576 2024.02.03
2024.02.03
18 36 22 S16W65 0660 FKC EKC beta-gamma-delta

area: 0960

13578 2024.02.04
2024.02.05
      S04W61        

location: S04W52

S9405 2024.02.05       N39W58            
S9406 2024.02.06       N14W30            
13579 2024.02.06
2024.02.07
      S09W51            
13581 2024.02.07
2024.02.08
1 2 1 S21W07 0060 HSX HSX location: S21W06

area: 0100

13582 2024.02.08
2024.02.10
13 8 5 N06W40 0170 EAI DAO

area: 0080

location: N04W41

apparently SWPC is including the spots of AR S9418 in their data for this spot group

13583 2024.02.08
2024.02.10
13 20 11 N09W13 0260 EHO FAO

area: 0410

location: N09W12

 
13584 2024.02.09
2024.02.10
3 10 5 S13E16 0020 HSX CSO area: 0050

location: S14E19

S9415 2024.02.10       N14W14            
S9416 2024.02.10       S07W36            
S9417 2024.02.10       N26W13            
S9418 2024.02.11   15 9 N09W34 0220   DAO  
13585 2024.02.12
2024.02.13
4 9 5 N15E47 0020 CRO CRO location: N13E48
S9421 2024.02.12       N28E12            
S9422 2024.02.12       S03W25            
S9423 2024.02.13   6 3 S22E52 0020   CRO  
13586 2024.02.13
2024.02.14
1 1 1 N29E68 0050   HSX location: N26E70

area: 0200

S9425 2024.02.14   6 3 S02E44 0015   CRO    
Total spot count: 53 113 65  
Sunspot number: 123 213 165  (total spot count + 10 * number of spotted regions)
Weighted SN: 96 162 114  (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): 135 117 132  

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
2022.07 125.4 129.5 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
2024.02 176.9 (1)   67.2 (2A) / 139.1 (2B) / 158.1 (2C) (116.3 projected, -0.8) (5.5)
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)  
2024.08       (113.1 projected, -1.4)  

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 February 11, 2024

The relatively high solar activity during the first weeks of 2024 has changed the outlook regarding solar max. The first peak in June 2023 currently has a less than 10% probability of being the actual solar max. The next candidate month is October 2023 (October 8-11 if zooming in on a specific date). The likelihood of October 2023 surpassing June 2023 is at least 50%. It is still likely that solar max will be sometime between October 2023 and March 2025.

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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.