Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 1, 2024 at 07:10 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 29. Solar wind speed at SOHO ranged between 368 and 450 km/sec. The high latitude magnetometer at Andenes recorded very quiet levels. The above 10 MeV proton flux was at background levels all day.

Solar flux density measured at 20h UT on 2.8 GHz was 164.1 - increasing 21.5 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.44. 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: 00112101 (planetary), 10222211 (Boulder), 00011000 (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 11 active regions using 2K resolution (SN: 266) and in 9 active regions using 1K resolution (SN: 164) SDO/HMI images.

Region 13590 [N18W67] produced low level C flares and lost most of the trailing spots. There's still a large magnetic delta structure in the eastern part of the huge leading penumbral area. A major flare is possible. C1 flares: C1.5 @ 06:33, C1.8 @ 07:39, C1.2 @ 11:01, C1.5 @ 12:13. C1.8 @ 20:06, C1.7 @ 20:42 UT
Region 13591 [S36W02] was quiet and stable.
Region 13592 [S14W04] was quiet and stable.
Region 13594 [N05W13] was mostly quiet and stable. C1 flares: C1.6 @ 15:00 UT
Region 13595 [N20W10] decayed slightly and was quiet.
Region 13596 [N18E23] was mostly quiet and stable. C1 flares: C1.6 @ 12:34 UT
Region 13597 [N07E01] decayed slowly and quietly.
New region 13598 [S13W19] emerged on February 28 and was numbered the next day by SWPC as development continued.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9453 [S16E10] was quiet and stable.
S9462 [N13E35] was quiet and stable.
New region S9466 [S15E83] rotated partially into view and could produce C flares. C1 flares: C1.3 @ 13:05, C1.9 @ 18:14, C1.8 @ 20:22 UT

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C4.0 05:13 southeast limb S9466 GOES18 incorrectly attributed to AR 13590 by SWPC
C2.3 13:34 southeast limb S9466 GOES16  
C2.5 16:57   13590 GOES16 simultaneous flare in AR S9466
C2.4 19:30 southeast limb S9466 GOES16  
C2.4 21:03   13590 GOES16 simultaneous flare in AR S9466
C2.4 21:50   13590 GOES16  
C2.2 22:08   13590 GOES16 simultaneous flare in AR S9466
C3.8 00:01   13590 GOES16 simultaneous flare in AR S9466

Coronal mass ejections (CMEs)

February 27, 29: No obviously Earth directed CMEs were observed.
February 28: A C5 flare in AR S9453 at 09:09 UT was associated with a partial halo CME. The CME could cause a weak disturbance on March 2-3.

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 on February March 1-3 with a chance of unsettled and active intervals on March 2-3 should the February 28 CME reach Earth.

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
13590 2024.02.18
2024.02.18
12 27 14 N18W65 1000 FKC EKC beta-gamma-delta

location: N18W67

13591 2024.02.22
2024.02.23
1 4 1 S36W04 0090 HSX CSO location: S36W02
13592 2024.02.22
2024.02.23
  27 11 S13W18 0040   BXO location: S14W04

SWPC location is a copy of that of AR 13598

13594 2024.02.22
2024.02.23
1 8 3 N05W13 0010 HRX HRX area: 0020
13595 2024.02.23
2024.02.24
12 32 19 N20W10 0320 DKO EAO

 

S9452 2024.02.23       S11W19            
S9453 2024.02.24   5   S16E10 0007   BXO  
S9454 2024.02.24       N08W00            
S9457 2024.02.25       N22W21          
13596 2024.02.25
2024.02.26
6 16 10 N18E24 0110 CAO DAO location: N18E23
S9459 2024.02.27       S23W33          
13597 2024.02.28
2024.02.28
4 10 4 N07E02 0010 BXO CRO area: 0020

location: N07E01

S9462 2024.02.28   2 1 N13E35 0003   AXX  
S9463 2024.02.28       N33W06 0005   AXX    
13598 2024.02.28
2024.02.29
1 23 11 S13W18 0010 HRX DAI location: S13W19

area: 0150

S9466 2024.02.29   2   S15E83 0030   CRO    
Total spot count: 37 156 74  
Sunspot number: 107 266 164  (total spot count + 10 * number of spotted regions)
Weighted SN: 78 195 113  (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): 118 146 131  

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
2024.02 172.5 168.3 116.9 (2A/2B) / 140.6 (2C) (116.3 projected, -0.8) 5.4
2024.03 (1)   (2A/2B) / 140.6 (2C) (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.