Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 13, 2024 at 04:20 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 on February 12. Solar wind speed at SOHO ranged between 413 and 643 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled levels. The above 10 MeV proton flux was at 94 pfu at the end of the day. A sudden and small increase in the total field of the IMF was recorded at DSCOVR at 01:45 UT on March 13.

Solar flux density measured at 20h UT on 2.8 GHz was 208.3 - increasing 28.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.13. 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 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.3). Three hour interval K indices: 22200000 (planetary), 11211201 (Boulder), 31100000 (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 14 active regions using 2K resolution (SN: 342) and in 10 active regions using 1K resolution (SN: 201) SDO/HMI images.

Region 13571 [S17W82] decayed slowly and quietly.
Region 13576 [S16W37] lost penumbral area. The magnetic delta structure in the northern part of the largest penumbra is still present. Another major flare is possible.
Region 13577 [N23W71] was quiet and stable.
Region 13578 [S05W24] reemerged with tiny spots.
Region 13581 [S21E19] was quiet and stable.
Region 13582 [N05W12] developed in the central spot section as new flux emerged.
Region 13583 [N09E15] has a small magnetic delta structure in the central spot section and could produce a minor M class flare. C1 flares: C1.9 @ 10:13 UT
Region 13584 [S15E46] was quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9406 [N14W04] was quiet and stable.
S9417 [N26E13] reemerged with tiny spots.
S9418 [N09W10] developed further and was mostly quiet.
New region S9420 [N13E76] rotated into view with mature spots.
New region S9421 [N28E38] was observed with tiny spots in an old plage area.
New region S9422 [S03E01] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.1 00:07   13576 GOES16  
C2.4 01:21   13576 GOES16  
C5.9 01:40 S17W26 13576 GOES16  
C6.3 01:51   13576 GOES16  
M6.5/2B 03:48 S17W26 13576 GOES16  
C2.2 05:23   13576 GOES16  
C6.9 05:54   13576 GOES16  
C6.2 06:06   13583 GOES16  
C2.1 07:15   13583 GOES16  
C2.2 08:32   13583 GOES16  
C2.9 08:44   13583 GOES16  
C3.8 11:26   S9420 GOES16  
C4.0 12:41   13583 GOES16  
M1.1 13:08   13576 GOES16  
C4.5 14:29   13576 GOES16  
M1.4/1F 15:48   13576 GOES16  
C5.8 17:26 behind northeast limb   GOES16  
C6.8 18:39   13576 GOES16  
C7.3 18:57   13576 GOES16  
C6.5 19:28   13583 GOES16  
M2.6 21:17 behind northeast limb   GOES16  
M1.6 22:04   13576 GOES16  

Coronal mass ejections (CMEs)

February 10: A full halo CME was observed after the M3.4 flare peaking at 03:54 UT. As this was a limb event,  chances are slim that the CME will reach Earth on February 12/13. A filament eruption beginning near 06 UT to the south of AR 13576 caused a CME that was observed off the south pole and the southern limbs. The major M9 flare in AR 13576 at 22:59 UT triggered a large filament eruption to the north of the spot group. A faint full halo CME was observed after the flare while a denser CME was observed over the north pole due to the filament eruption. The halo CME could impact Earth on February 13.
February 11: 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]

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 due to a proton event. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to minor storm onFebruary 13-14 due to CME effects and quiet on February 15.

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
13571 2024.01.31
2024.02.01
2 4 1 S17W82 0030 CSO CAO

area: 0060

13574 2024.02.01
2024.02.01
      N16W74          

location: N16W71

13577 2024.02.02
2024.02.05
  4 2 N22W71 0010   BXO

location: N23W71

13576 2024.02.03
2024.02.03
40 79 37 S17W37 0420 FKC FKI beta-gamma-delta

area: 0600

location: S16W37

13578 2024.02.04
2024.02.05
  6 1 S04W33 0010   AXX  

location: S05W24

S9405 2024.02.05       N39W32            
S9406 2024.02.06   4   N14W04 0005   BXO  
13579 2024.02.06
2024.02.07
1     S09W24   AXX BXO    
13581 2024.02.07
2024.02.08
2 3 3 S21E18 0050 HSX HSX location: S21E19

area: 0140

S9411 2024.02.08       S16W55            
13582 2024.02.08
2024.02.10
15 20 15 N07W13 0120 DAI DSO

area: 0160

location: N05W12

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

13583 2024.02.08
2024.02.10
22 44 26 N09E15 0250 DKI EAI beta-gamma-delta

area: 0460

 
13584 2024.02.09
2024.02.10
1 6 2 S15E46 0030 HSX CAO area: 0060
S9415 2024.02.10       N14E12            
S9416 2024.02.10       S07W10          
S9417 2024.02.10   2   N26E13 0002   BXO    
S9418 2024.02.11   25 12 N09W10 0280   DAI  
S9420 2024.02.12   2 2 N13E76 0080   HAX    
S9421 2024.02.12   2   N28E38 0002   AXX    
S9422 2024.02.12   1   S03E01 0002   AXX    
Total spot count: 83 202 101  
Sunspot number: 153 342 201  (total spot count + 10 * number of spotted regions)
Weighted SN: 123 247 146  (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): 168 188 161  

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
2024.02 174.8 (1)   58.7 (2A) / 141.9 (2B) / 160.8 (2C) (116.3 projected, -0.8) (5.0)
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.