Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 12, 2024 at 07:20 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 on March 11. Solar wind speed at SOHO ranged between 351 and 404 km/sec. The high latitude magnetometer at Andenes recorded quiet levels. The above 10 MeV proton flux was background levels at the end of the day.

Solar flux density measured at 20h UT on 2.8 GHz was 126.7 - decreasing 68.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 156.39. 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: 11210101 (planetary), 01222322 (Boulder), 20200002 (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 13 active regions using 2K resolution (SN: 221) and in 10 active regions using 1K resolution (SN: 142) SDO/HMI images.

Region 13599 [S12W56] still has a significant magnetic delta structure in the leading spot section and gained area. A major flare is possible. C1 flares: C1.1 @ 09:57, C1.6 @ 11:57, C1.1 @ 00:15 (on March 12, the flare began late on March 11) UT
Region 13600 [S18W43] decayed slowly and quietly.
Region 13602 [N16W65] was quiet and stable.
Region 13604 [N09W08] decayed slowly and quietly.
Region 13605 [S15W30] decayed slowly and quietly.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9484 [S15E27] was quiet and stable.
S9488 [N09E42] developed slowly and quietly.
S9489 [N11E69] was quiet and stable.
New region S9490 [S14W37] emerged before noon, then decayed slowly.
New region S9491 [N06E38] emerged with a tiny spot.
New region S9492 [N06E77] rotated into view with tiny spots.
New region S9493 [S18E59] is an emerging region, currently with tiny spots.
New region S9494 [N26E30] was observed with tiny spots in an old plage area.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C5.8 08:50   13599 GOES16  

Coronal mass ejections (CMEs)

March 9-11: 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 positive polarity northern hemisphere coronal hole (CH1204) rotated across the central meridian on March 10.

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 March 12-15 with a a chance of unsettled intervals on March 13-14 due to effects from CH1204.

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
13599 2024.02.29
2024.03.01
13 31 17 S12W55 0160 DAI DKC beta-gamma-delta

area: 0320

location: S12W56

13600 2024.03.01
2024.03.02
1 5 2 S17W44 0010 AXX CRO

location: S18W43

13602 2024.03.03
2024.03.04
1 3 2 N16W66 0010 HRX HRX area: 0015

location: N16W65

13603 2024.03.03
2024.03.04
      N13W44           location: N13W38
13604 2024.03.04
2024.03.05
  15 5 N08W13 0025   BXO

location: N09W08

S9478 2024.03.05       S08W17          
S9480 2024.03.06       N07W43            
13605 2024.03.07
2024.03.07
1 9 5 S15W31 0010 BXO CRO

location: S15W30

S9484 2024.03.07   3   S15E27 0006   AXX  
S9485 2024.03.08       S33W10            
S9486 2024.03.09       S30W52            
S9487 2024.03.10       N22W36          
S9488 2024.03.10   10 6 N09E42 0040   DRO  
S9489 2024.03.10   2 1 N11E69 0008   HRX  
S9490 2024.03.11   3 2 S14W37 0008   BXO    
S9491 2024.03.11   1   N06E38 0002   AXX    
S9492 2024.03.11   2 1 N06E77 0006   AXX    
S9493 2024.03.11   5   S18E59 0010   BXO    
S9494 2024.03.11   2 1 N26E30 0004   AXX    
Total spot count: 16 91 42  
Sunspot number: 56 221 142  (total spot count + 10 * number of spotted regions)
Weighted SN: 21 116 67  (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): 62 122 114  

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
2024.03 138.3 (1)   34.3 (2A) / 96.5 (2B) / 121.3 (2C) (116.9 projected, -0.6) (9.4)
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 March 10, 2024

Solar activity saw a significant decrease during the latter half of February and the first part of March. While there is still a chance that there could be another and higher peak in October or November 2023, chances that June 2023 was solar max has increased. After November 2023 there is currently no other obvious candidate solar max month. Taking into account the state of the solar polar fields another major peak during SC25 is becoming less likely.

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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.