Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 16, 2024 at 07:00 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 very quiet on February 15. Solar wind speed at SOHO ranged between 366 and 464 km/sec. The high latitude magnetometer at Andenes recorded quiet to unsettled levels. The above 10 MeV proton flux was at 3 pfu at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 178.3 - increasing 18.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.18. 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: 3.1). Three hour interval K indices: 10110011 (planetary), 10122221 (Boulder), 00000031 (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: 270) and in 13 active regions using 1K resolution (SN: 188) SDO/HMI images.

Region 13576 [S17W78] decayed nearly losing the magnetic delta structures. The region produced many C flares and one M flare as it rotated to the southwest limb. C1 flares: C1.8 @ 02:15, C1.5 @ 03:05, C1.8 @ 04:12, C1.7 @ 06:25 UT. The region produced a major, impulsive X2.5 flare at 06:53 UT on February 16.
Region 13581 [S21W19] decayed slowly and quietly.
Region 13582 [N04W56] decayed slowly and lost the trailing spots.
Region 13583 [N09W27] decayed slowly and was mostly quiet.
Region 13584 [S14E07] decayed slowly and quietly.
Region 13585 [N13E32] decayed slowly and quietly.
Region 13586 [N27E58] was mostly quiet and stable.
New region 13587 [S21E37] rotated into view on February 13 and developed slowly on Feb.15 when the spot group was numbered by SWPC. C1 flares: C1.6 @ 04:55 UT
New region 13588 [S02E30] emerged on February 14 and decayed the next day as SWPC numbered the region.
New region 13589 [S08W51] emerged with small spots.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9418 [N10W49] decayed quickly and was mostly quiet.
S9421 [N26W08] reemerged with tiny spots.
New region S9427 [N26W53] emerged with tiny spots.
New region S9428 [S12E33] was observed with tiny spots in an old plage area.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.8 00:18   13576 GOES16  
C3.8 00:50   13576 GOES16  
C2.9 02:35   13576 GOES16  
C2.4 03:40   13576 GOES16  
C2.2 03:58   13587 GOES16  
C2.1 05:20   13576 GOES16  
C3.2 05:33   13576 GOES16  
C4.0 05:40   13587 GOES16  
C5.1 08:11   13586 GOES16  
C3.5 08:37   13576 GOES16  
C2.8 09:35   13576 GOES16  
C2.4 09:58   13576 GOES16  
C4.5 10:24   13576 GOES16  
C3.3 11:13   13576 GOES16  
C3.1 11:20   13576 GOES16  
C2.7 11:42 S16W78 13576 GOES16  
C2.6 12:15   13576 GOES16  
C2.7 12:50 S16W78 13576 GOES16  
C2.5 14:17   13576 GOES16  
C4.3 14:56 N07W23 13583 GOES16  
C4.7 15:20 S16W80 13576 GOES16  
M1.8 17:07   13576 GOES16  
C8.1 18:13   13576 GOES16  
C3.8 19:17   13576 GOES16  
C2.2 21:04   13576 GOES16  
C2.2 21:29   13576 GOES16  
C2.1 21:36   13576 GOES16  
C2.1 21:48   13576 GOES16  
C2.6 22:42   13589 GOES16 attributed by SWPC to simultaneous flare in AR 13576
C3.9 00:27 (flare start: 23:49)   13589 GOES16  

Coronal mass ejections (CMEs)

February 13-15: No obviously Earth directed CMEs were observed.

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 negative polarity coronal hole in the southern hemisphere developed on February 14 and was 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 to fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on February 16-18.

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
12 19 9 S16W82 0510 FKC CKO beta-gamma

area: 0720

13578 2024.02.04
2024.02.05
      S04W76          

location: S04W65

S9406 2024.02.06       N14W43            
13579 2024.02.06
2024.02.07
      S09W66            
13581 2024.02.07
2024.02.08
1 2 1 S22W20 0050 HSX HSX location: S21W19

area: 0080

13582 2024.02.08
2024.02.10
12 2 1 N07W53 0140 EAI HSX

area: 0060

location: N04W56

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

13583 2024.02.08
2024.02.10
10 23 13 N09W26 0270 ESO FSO

area: 0360

location: N09W27

 
13584 2024.02.09
2024.02.10
1 14 3 S15E07 0020 HRX CRO area: 0030

location: S14E07

S9415 2024.02.10       N14W27            
S9416 2024.02.10       S07W49            
S9417 2024.02.10       N26W26            
S9418 2024.02.11   16 10 N10W49 0050   DRI  
13585 2024.02.12
2024.02.13
3 13 3 N13E33 0010 BXO BXO location: N13E32
S9421 2024.02.12   3 1 N26W02 0005   AXX    
S9422 2024.02.12       S03W25            
13587 2024.02.13
2024.02.15
5 14 5 S21E37 0020 CRO CRI area: 0030
13586 2024.02.13
2024.02.15
1 2 1 N27E57 0100 HSX HSX location: N27E58

area: 0220

13588 2024.02.14
2024.02.15
2 4 2 S03E30 0010 BXO BXO location: S02E30
13589 2024.02.15
2024.02.15
4 10 6 S08W52 0010 BXO DRO   was AR S9426

area: 0050

S9427 2024.02.15   5 3 N26W53 0020   DRO    
S9428 2024.02.15   3   S12E33 0005   AXX    
Total spot count: 51 130 58  
Sunspot number: 151 270 188  (total spot count + 10 * number of spotted regions)
Weighted SN: 87 175 103  (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): 166 149 150  

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
2024.02 177.0 (1)   72.4 (2A) / 139.9 (2B) / 156.7 (2C) (116.3 projected, -0.8) (5.3)
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)  
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.

--------------------------------------------------------------------------------------

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.