Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 22, 2024 at 08:00 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 (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 minor storm on March 21 due to CME effects. Solar wind speed at SOHO ranged between 301 and 448 km/sec. The high latitude magnetometer at Andenes recorded quiet to major storm levels. The above 10 MeV proton flux was at background levels at the end of the day. A weak solar wind shock was observed at ACE at 01:49 UT, the arrival of the March 17 CME.

Solar flux density measured at 17h UT on 2.8 GHz was 181.3 (the measurements at 20 and 23h UT were both flare enhanced by the long duration event associated with a massive filament eruption to the north of AR 13614) - increasing 9.6 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 156.57. 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 23 (STAR Ap - based on the mean of three hour interval ap indices: 23.0). Three hour interval K indices: 32324544 (planetary), 32335544 (Boulder), 31225656 (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 15 active regions using 2K resolution (SN: 371) and in 15 active regions using 1K resolution (SN: 269) SDO/HMI images.

Region 13607 [S18W75] decayed slowly and quietly.
Region 13608 [N10W66] was quiet and stable.
Region 13611 [N29W27] reemerged with tiny spots.
Region 13613 [S22W82] decayed slowly and quietly.
Region 13614 [N17E19] lost the magnetic delta and has many tiny spots. An M class flare is still possible.
Region 13615 [S12E26] lost several small magnetic delta structures, however, the number of spots continued to increase. While the spot group was more quiet than during recent days, there is still a chance of another major flare. C1 flares: C1.8 @ 01:18, C1.6 @ 01:47, C1.7 @ 02:25 UT
Region 13616 [N02W75] decayed slowly and was quiet.
Region 13617 [S13E57] gained spots and was mostly quiet.
New region 13618 [S19W62] emerged on March 19 and was numbered by SWPC 2 days later as the spot group developed further.
New region 13619 [N19E58] rotated into view on March 20 with SWPC numbering the region the following day.

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9524 [S08W67] decayed slowly and quietly.
S9525 [N17W10] was quiet and stable.
New region S9528 [N19E73] rotated into view with a small spot.
New region S9529 [S22E19] emerged with tiny spots in an old plage area.
New region S9530 [N37E06] was observed with a tiny spot in an old plage area.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C3.7 00:06   13615 GOES16  
C3.2 00:22   13615 GOES16  
C2.2 03:18   13615 GOES16  
C2.9 03:53   13615 GOES16  
C2.2 04:45   13618 GOES18  
C2.1 05:56   13618 GOES18  
C2.4 07:16   13618 GOES16  
C8.7 11:32   13615 GOES16  
C2.3 12:41   13617 GOES16  
C2.2 12:55   13615 GOES16  
C2.0 14:32   13617 GOES16  
C2.7 16:01   13617 GOES16  
C2.6 16:11   13615 GOES16  
C2.0 17:27   13617 GOES16  
C5.8 18:19   13614 GOES16 triggered by large filament eruption just north of AR 13614
C4.7 18:43   13619 GOES16  
C4.1 19:22   13615 GOES16  
C3.8 20:34   13614 GOES16  
C3.7 21:04   13615 GOES16  
C3.1 21:25   13615 GOES16  
C2.7 22:15   13619 GOES16  
C2.7 22:37   13615 GOES16  

Coronal mass ejections (CMEs)

March 19-21: 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 negative polarity southern hemisphere coronal hole (CH1207) will rotate across the central meridian on March 20-22.

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 22 due to CME effects. A high speed stream associated with CH1207 could reach Earth on March 23 and cause unsettled to minor storm conditions lasting until March 25.

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
13608 2024.03.10
2024.03.13
3 5 3 N10W66 0020 CRO DRO  
13609 2024.03.11       N06W67           location: N05W56
13607 2024.03.11
2024.03.13
5 7 4 S19W76 0120 DSO DRO

location: S18W75

area: 0090

13610 2024.03.12
2024.03.13
      S16W42           location: S15W33
13611 2024.03.13
2024.03.14
  3 1 N28W31 0005   AXX  

location: N29W27

13613 2024.03.15
2024.03.16
2 3 3 S24W82 0070 CAO CAO

area: 0040

location: S22W82

13616 2024.03.16
2024.03.18
1 1 1 N02W73 0020 HSX HAX

location: N02W75

area: 0030

13614 2024.03.16
2024.03.17
4 47 12 N17E18 0180 DSO DSC

area: 0290

S9509 2024.03.16       S06W56            
S9510 2024.03.17       S22W47            
13615 2024.03.17
2024.03.18
24 105 60 S12E25 0310 EKC FAC beta-gamma-delta

area: 0550

location: S12E26

S9512 2024.03.17       N20W56            
S9513 2024.03.17       S15W35            
S9514 2024.03.17       S30W23            
S9515 2024.03.17       N09E19            
S9518 2024.03.18       N26W43            
S9519 2024.03.18       N09W06            
13618 2024.03.19
2024.03.21
5 13 9 S20W62 0060 DAO DAO location: S19W62

area: 0130

13617 2024.03.19
2024.03.20
2 15 11 S15E56 0150 CAO CAO area: 0180

location: S13E57

S9524 2024.03.20   4 2 S08W67 0007   BXO  
S9525 2024.03.20   4 3 N17W10 0012   CRO  
13619 2024.03.20
2024.03.21
5 7 4 N17E61 0130 CAO CAO location: N19E58
S9527 2024.03.20       N05E04          
S9528 2024.03.21   1 1 N19E73 0010   HRX    
S9529 2024.03.21   5 4 S22E19 0020   BXO    
S9530 2024.03.21   1 1 N37E06 0008   AXX    
Total spot count: 51 221 119  
Sunspot number: 141 371 269  (total spot count + 10 * number of spotted regions)
Weighted SN: 99 268 166  (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): 155 204 215  

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
2024.03 144.1 (1)   65.6 (2A) / 96.8 (2B) / 122.4 (2C) (116.9 projected, -0.6) (8.0)
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.