Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 3, 2024 at 09:15 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 (March 2, 2024)
Solar cycle Solar cycles 23-25 (March 2, 2024) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (March 2, 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 (March 2, 2024) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (March 2, 2024) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (March 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 March 2. Solar wind speed at SOHO ranged between 278 and 404 km/sec. The high latitude magnetometer at Andenes recorded quiet to active 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 152.3 - decreasing 18.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.34. 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 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.8). Three hour interval K indices: 21111001 (planetary), 21112210 (Boulder), 43001113 (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: 200) and in 9 active regions using 1K resolution (SN: 131) SDO/HMI images.

Region 13591 [S36W27] was mostly quiet and stable. C1 flares: C1.8 @ 08:23, C1.5 @ 09:12, C1.5 @ 12:30, C1.5 @ 14:26, C1.4 @ 17:35, C1.2 @ 21:28 UT
Region 13592 [S13W33] decayed slowly and quietly.
Region 13595 [N20W37] decayed slowly and produced a few C flares. C1 flares: C1.4 @ 11:04 UT
Region 13596 [N19W05] decayed slowly and quietly.
Region 13598 [S12W47] developed early in the day, then decayed slowly. C flares are possible.
Region 13599 [S13E63] was quiet and stable.
New region 13600 [rotated into view on March 1 and was numbered the next day by SWPC.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9453 [S18W19] was quiet and stable.
S9457 [N22W47] reemerged with tiny spots.
S9469 [S22E31] was quiet and stable.
New region S9471 [N12E05] emerged with tiny spots.

A C1.8 flare was recorded at 23:46 UT and had its origin behind the southwest limb.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.0 02:36   13598 GOES16  
C2.9 05:17   13590 GOES16 LDE
C2.6 06:09   13590 GOES16  
C2.0 11:24   13595 GOES16  
C6.6 12:58   13595 GOES16  

Coronal mass ejections (CMEs)

February 29 - March 2: 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 southern hemisphere coronal hole (CH1203) will likely rotate into an Earth facing position on March 5.

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 to unsettled on March 3-5.

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
13591 2024.02.22
2024.02.23
3 7 5 S36W28 0070 CSO CSO location: S36W27

area: 0090

13592 2024.02.22
2024.02.23
  4 3 S14W34 0010   AXX location: S13W33
13594 2024.02.22
2024.02.23
      N05W42          
13595 2024.02.23
2024.02.24
8 20 10 N20W37 0380 EKO EHO

area: 0450

S9452 2024.02.23       S11W45            
S9453 2024.02.24   2   S18W19 0003   AXX  
S9454 2024.02.24       N08W26            
S9457 2024.02.25   2   N22W47 0002   AXX    
13596 2024.02.25
2024.02.26
3 7 2 N19W03 0030 CAO CAO location: N19W05

area: 0050

S9459 2024.02.27       S23W59            
13597 2024.02.28
2024.02.28
      N08W27          
S9462 2024.02.28       N13E09            
13598 2024.02.28
2024.02.29
12 26 12 S13W45 0110 DAI DAI location: S12W47

area: 0220

13599 2024.02.29
2024.03.01
4 9 4 S13E60 0030 CRO HAX area: 0080

location: S13E63

13600 2024.03.01
2024.03.02
1 4 2 S18E73 0080 HSX CSO area: 0180
S9469 2024.03.01   4 1 S22E31 0010   AXX  
S9471 2024.03.02   5 2 N12E05 0010   BXO    
Total spot count: 31 90 41  
Sunspot number: 91 200 131  (total spot count + 10 * number of spotted regions)
Weighted SN: 64 125 76  (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): 100 110 105  

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
2022.08 114.2 117.1 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  153.7 157.6 114.8 124.0 (-0.3) 7.19
2023.09  154.4 156.0 134.2 (124.2 projected, +0.2) 14.26
2023.10  142.8 141.9 99.4 (125.0 projected, +0.8) 8.16
2023.11 153.5 150.2 105.4 (125.0 projected, -0.0) 12.20
2023.12 151.1 146.4 114.2 (121.7 projected, -3.3) 9.60
2024.01 164.6 159.3 123.0 (118.3 projected, -3.4) 5.46
2024.02 172.5 168.3 124.6 (117.5 projected, -0.8) 5.4
2024.03 152.6 (1)   6.8 (2A) / 105.5 (2B) / 138.8 (2C) (116.9 projected, -0.6) (5.7)
2024.04       (116.9 projected, -0.0)  
2024.05       (118.1 projected, +1.2)  
2024.06       (117.3 projected, -0.8)  
2024.07       (115.6 projected, -1.7)  
2024.08       (113.7 projected, -1.9)  
2024.09       (112.0 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 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.