Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 6, 2024 at 04:25 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 unsettled on March 5. Solar wind speed at SOHO ranged between 370 and 480 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm 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 141.5 - decreasing 46.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.01. 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 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.6). Three hour interval K indices: 31222121 (planetary), 22213221 (Boulder), 51122130 (Andenes).

The background x-ray flux is at the class B7 level (GOES 16).

At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 215) and in 10 active regions using 1K resolution (SN: 135) SDO/HMI images.

Region 13591 [S36W65] was quiet and stable. C1 flares: C1.4 @ 23:51 UT
Region 13592 [S14W70] decayed slowly and quietly.
Region 13595 [N20W78] decayed slowly and was mostly quiet.
Region 13596 [N20W44] decayed slowly and quietly.
Region 13598 [S14W82] rotated partly out of view and was mostly quiet. C1 flares: C1.1 @ 09:52, C1.9 @ 22:29 UT
Region 13599 [S12E26] developed slowly and was mostly quiet. C1 flares: C1.5 @ 04:03, C1.9 @ 14:23 UT
Region 13600 [S18E36] was mostly quiet and stable. C1 flares: C1.0 @ 14:56 UT
Region 13601 [N13W35] decayed slowly and quietly.
Region 13602 [N16E14] decayed further and was quiet.
Region 13603 [N13E39] was quiet and stable.
New region 13604 [N08E71] rotated into view on March 4 and was numbered the next day by SWPC. C1 flares: C1.0 @ 15:04 UT

Spotted regions not observed (or interpreted differently) by SWPC/USAF:
S9469 [S23W07] was quiet and stable.
S9475 [N12W46] decayed slowly and quietly.
New region S9478 [S07E54] was observed with tiny spots in an old plage area.

C2+ flares

Magnitude Peak time (UT) Location Source Recorded by Comment
C2.6 11:25   13598 GOES16  

Coronal mass ejections (CMEs)

March 3-5: 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 to fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on March 6-7. A weak disturbance associated with CH1203 could begin on March 8 and cause quiet to active conditions.

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 2 2 S36W66 0040 HSX HSX

area: 0060

klocation: S36W65

13592 2024.02.22
2024.02.23
  2   S14W74 0004   AXX location: S14W70
13594 2024.02.22
2024.02.23
      N05W87           location: N06W80
13595 2024.02.23
2024.02.24
2 2 2 N21W74 0190 DSO EHO

area: 0420

location: N20W78

S9453 2024.02.24       S15W54            
13596 2024.02.25
2024.02.26
1 1 1 N20W45 0010 AXX AXX

area: 0004

location: N20W44

13597 2024.02.28
2024.02.28
      N08W69            
S9462 2024.02.28       N13W30            
13598 2024.02.28
2024.02.29
1 2   S11W88 0010 BXO AXX location: S14W82

area: 0003

13599 2024.02.29
2024.03.01
6 30 16 S13E25 0070 DSI DAI area: 0180

location: S12E26

13600 2024.03.01
2024.03.02
1 4 2 S18E33 0070 HSX CAO area: 0140

location: S18E36

S9469 2024.03.01   6 1 S23W07 0010   AXX  
13601 2024.03.02
2024.03.03
3 4 1 N14W37 0010 BXO BXO

location: N13W35

13602 2024.03.03
2024.03.04
4 8 4 N20E16 0050 CSO CSO area: 0080

location: N16E14

13603 2024.03.03
2024.03.04
1 6 3 N14E40 0040 HSX CAO location: N13E39

area: 0070

S9474 2024.03.03       S21W27            
S9475 2024.03.04   2   N12W46 0005   AXX  
13604 2024.03.04
2024.03.05
1 4 3 N08E71 0070 HAX HAX  
S9478 2024.03.04   2   S07E54 0003   BXO    
Total spot count: 21 75 35  
Sunspot number: 121 215 135  (total spot count + 10 * number of spotted regions)
Weighted SN: 56 115 75  (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): 133 118 108  

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
2024.03 146.4 (1)   17.3 (2A) / 107.0 (2B) / 135.8 (2C) (116.9 projected, -0.6) (11.0)
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 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.