Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 8, 2024 at 06:20 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 (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 to active on March 7. Solar wind speed at SOHO ranged between 370 and 450 km/sec. The high latitude magnetometer at Andenes recorded quiet to major storm levels. A disturbance related to CH1203 started after 16h UT. The above 10 MeV proton flux was at background levels all day.

Solar flux density measured at 20h UT on 2.8 GHz was 136.6 - decreasing 46.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 156.77. 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 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.3). Three hour interval K indices: 32222343 (planetary), 32223323 (Boulder), 22333365 (Andenes).

The background x-ray flux is at the class B4 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 230) and in 8 active regions using 1K resolution (SN: 145) SDO/HMI images.

Region 13591 [S36W87] rotated partly out of view.
Region 13599 [S12W02] developed during the first half of the day, then decayed slowly after noon. The spot group still has polarity intermixing and could produce a minor M class flare. Many C flares were recorded during the day. C1 flares: C1.1 @ 02:40, C1.0 @ 04:13, C1.3 @ 04:33, C1.0 @ 05:52, C1.6 @ 07:20, C1.9 @ 08:35, C1.0 @ 10:11, C1.6 @ 11:28, C1.0 @ 12:53, C1.1 @ 14:00, C1.0 @ 15:08, C1.0 @ 15:47, C1.0 @ 16:39, C1.7 @ 17:11, C1.3 @ 17:30, C1.3 @ 17:58 UT
Region 13600 [S18E09] was quiet and stable.
Region 13602 [N15W12] was quiet and stable.
Region 13603 [N14E12] was quiet and stable.
Region 13604 [N07E44] was mostly quiet and stable.
New region 13605 [S15E27] emerged with several spots.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9469 [S18W37] decayed slowly and quietly.
S9478 [S06E19] was quiet and stable.
New region S9483 [N12W53] emerged with a tiny spot.
New region S9484 [S08E62] emerged with a tiny spot.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C8.3 06:18 S12E10 13599 GOES16  
C2.0 09:52   13599 GOES16  
C4.0 10:28 S12E08 13599 GOES16  
C3.2 10:36   13599 GOES16  
C6.3 12:07   13599 GOES16  
C3.3 12:20   13599 GOES16  
C2.3 16:51   13599 GOES16  
C3.5 22:33 behind northwest limb 13595 GOES16 CME, moderate type II radio sweep
C4.6 23:35 N06E42 13604 GOES16  

Coronal mass ejections (CMEs)

March 5-7: 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) was in 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. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet to active on March 8 due to effects from CH1203 and quiet to unsettled on March 9-10.

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
1 1   S37W89 0030 HSX HSX

area: 0060

13596 2024.02.25
2024.02.26
      N20W73        

location: N19W79

S9462 2024.02.28       N13W56            
13599 2024.02.29
2024.03.01
16 50 31 S12W02 0140 DAI DAC beta-gamma

area: 0210

13600 2024.03.01
2024.03.02
3 17 10 S18E08 0070 HSX CAO area: 0130

location: S18E09

S9469 2024.03.01   1 1 S18W37 0003   AXX  
13601 2024.03.02
2024.03.03
      N14W65          

location: N13W61

13602 2024.03.03
2024.03.04
2 11 7 N17W13 0030 CSO CAO area: 0050

location: N15W12

13603 2024.03.03
2024.03.04
2 5 4 N14E13 0060 HAX CAO location: N14E12

area: 0050

S9474 2024.03.03       S21W53            
13604 2024.03.04
2024.03.05
1 10 3 N08E43 0020 HSX CAO location: N07E44

area: 0050

S9478 2024.03.05   9   S06E19 0015   BXO  
S9479 2024.03.06       N01W46          
S9480 2024.03.06       N07E09          
S9481 2024.03.06       S02W16          
13605 2024.03.07
2024.03.07
4 12 8 S15E26 0020 DAO DRO   was AR S9482

location: S15E27

area: 0040

S9483 2024.03.07   3 1 N12W53 0007   BXO    
S9484 2024.03.07   1   S08E62 0001   AXX    
Total spot count: 29 120 65  
Sunspot number: 99 230 145  (total spot count + 10 * number of spotted regions)
Weighted SN: 64 154 99  (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): 109 127 116  

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) 5.31
2024.03 143.5 (1)   23.8 (2A) / 105.6 (2B) / 130.7 (2C) (116.9 projected, -0.6) (10.3)
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.