Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 11, 2023 at 12:00 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 3, 2023)
Solar cycle Solar cycles 23-25 (March 1, 2023) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24-25 progress (March 1, 2023) 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 1, 2023) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12-14, 16, 24-25 (March 1, 2023) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (January 21, 2023) 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

Recent activity

The geomagnetic field was quiet to unsettled on March 10. Solar wind speed at SOHO ranged between 356 and 436 km/sec. The high latitude magnetometer at Andenes recorded quiet to major storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 171.2 - decreasing 38.3 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 136.85). The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 8.8). Three hour interval K indices: 32201323 (planetary), 31202323 (Boulder), 61102345 (Andenes).

The background x-ray flux was 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: 267) and in 13 active regions using 1K resolution (SN: 186) SDO/HMI images.

Region 13239 [N33W59] was quiet and stable.
Region 13240 [S16W42] was mostly quiet and stable.
Region 13241 [N29W45] was quiet and stable.
Region 13242 [N10W48] decayed quickly and was mostly quiet. C1 flares: C1.6 @ 11:32 UT
Region 13245 [S22W17] decayed slowly and produced a few C flares.
Region 13246 [N24E02] was quiet and stable.
Region 13247 [S23E15] was quiet and stable.
Region 13249 [S12E37] was quiet and stable.
Region 13250 [S19E32] was mostly quiet and gained area. C1 flares: C1.5 @ 02:14 UT
Region 13251 [S13E57] was quiet and stable.
New region 13252 [N12E59] rotated into view on March 9 and was numbered by SWPC the next day.

Spotted regions not observed (or interpreted differently) by SWPC:
S8348 [N23E48] was mostly quiet and stable.
New region S8354 [S15W07] emerged with tiny spots before noon, then decayed slowly.
New region S8355 [N12E25] was observed with tiny spots in an old plage area.
New region S8356 [S28E43] was observed with tiny spots in an old plage area.

A large filament eruption was observed across the equator in the western hemisphere from AR 13245 and southwards. Most of the eruption was observed in the southwest quadrant and began at 16:15 UT according to SDO/AIA imagery peaking between 17 and 18h UT. A partial halo CME was observed.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment
C7.1/1F 07:08 S24E00 13245 GOES16  
C4.5/1F 10:06   13242 GOES16 incorrectly attributed to AR 13245 by SWPC
C3.9 10:24   13245 GOES16 incorrectly attributed to AR 13242 by SWPC
C2.5 13:33 S13W65 S8327 GOES16  
C3.2 14:55   13250 GOES16 incorrectly attributed to AR 13245 by SWPC
C2.8 15:20   13245 GOES16  
C2.0 20:49   S8348 GOES16  

Coronal mass ejections (CMEs)

March 8-9: No obviously Earth directed CMEs were observed.
March 10: A partial halo CME was observed after a large filament eruption in the southwestern and northwestern quadrants. The CME could reach Earth after noon on March 13 and cause unsettled to minor storm conditions.

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 trans equatorial coronal hole (CH1134) will likely rotate into an Earth facing position on March 11-12.

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

Quiet to unsettled is likely on March 11 becoming quiet on March 12-13. Unsettled and active intervals are possible on March 14-15 due to effects from CH1134.

Coronal holes (1) Coronal mass ejection (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
13239 2023.02.27
2023.02.28
1 1 1 N32W57 0070 HSX HSX location: N33W59

area: 0110

13241 2023.02.28
2023.03.01
1 4 2 N28W48 0030 HAX CSO

location: N29W45

area: 0040

13240 2023.02.28
2023.03.01
  4   S09W77 0005   BXO

location: S16W42

SWPC on March 6 moved the location to near AR S8327

13242 2023.03.01
2023.03.02
7 12 4 N10W44 0110 CSO CSO

location: N10W48

area: 0230

13245 2023.03.02
2023.03.03
9 35 15 S23W18 0220 CSI DKO

area: 0360

location: S22W17

S8330 2023.03.03       S17W27            
13246 2023.03.04
2023.03.05
3 5 5 N25W00 0050 CAO CAO location: N24E02

area: 0080

S8335 2023.03.04       N22W41            
S8336 2023.03.04       S08W33            
13247 2023.03.05
2023.03.06
6 18 9 S23E16 0070 CSO CSI location: S23E15

area: 0100

S8341 2023.03.05       S04W48            
S8343 2023.03.06       S12W17            
13249 2023.03.07
2023.03.07
1 4 2 S11E34 0070 HSX HSX location: S12E37

area: 0100

S8346 2023.03.07       N33E23          
S8348 2023.03.08   3 1 N23E48 0010   CRO  
13251 2023.03.08
2023.03.09
1 2 1 S13E55 0050 HSX HSX area: 0100

location: S13E57

S8350 2023.03.08       N13W03            
13252 2023.03.09
2023.03.10
1 1 1 N16E60 0020 HSX HSX location: N12E60

area: 0040

13250 2023.03.09
2023.03.09
5 21 13 S20E32 0010 BXO DRI location: S19E32

area: 0110

S8353 2023.03.09       S29W34          
S8354 2023.03.10   2   S15W07 0002   AXX    
S8355 2023.03.10   3 1 N12E25 0005   AXX    
S8356 2023.03.10   2 1 S28E43 0003   AXX    
Total spot count: 35 117 56  
Sunspot number: 135 267 186  (total spot count + 10 * number of spotted regions)
Weighted SN: 80 173 112  (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): 149 147 149  

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
2021.08 77.7 79.7 22.0 35.4 (+4.0) 6.19
2021.09 87.0 88.2 51.3 40.2 (+4.8) 6.33
2021.10 88.9 88.3 37.4 45.2 (+5.0) 7.38
2021.11 86.2 84.4 34.8 50.8 (+5.6) 9.83
2021.12 103.0 99.8 67.5 55.9 (+5.1) 6.40
2022.01 103.8 100.5 55.3 60.1 (+4.2) 8.92
2022.02 109.1 106.5 60.9 64.7 (+4.6) 10.46
2022.03 117.0 115.8 78.6 68.7 (+4.0) 10.20
2022.04 130.8 131.7 84.0 73.0 (+4.3) 11.79
2022.05 133.8 136.8 96.5 77.2 (+4.2) 7.48
2022.06 116.1 119.8 70.3 80.9 (+3.7) 8.20
2022.07 125.4 129.5 91.4 86.5 (+5.6) 9.51
2022.08 114.2 117.1 74.6 92.3 (+5.8) 10.92
2022.09 135.1 136.5 96.0 (97.0 projected, +4.7) 12.18
2022.10 133.5 132.7 95.4 (100.2 projected, +3.2) 11.16
2022.11 123.4 120.7 77.6 (103.0 projected, +2.8) 9.33
2022.12 147.9 143.4 113.1 (107.8 projected, +4.8) 10.99
2023.01 182.4 176.6 143.6 (113.8 projected, +6.0) 8.73
2023.02 167.2 163.2 110.9 (118.9 projected, +5.1) 14.6
2023.03 176.8 (1)   44.7 (2A) / 138.5 (2B) / 158.7 (2C) (122.0 projected, +3.1) (13.2)
2023.04       (127.4 projected, +5.4)  
2023.05       (133.2 projected, +5.8)  
2023.06       (136.4 projected, +3.2)  
2023.07       (135.9 projected, -0.5)  
2023.08       (136.9 projected, +1.0)  
2023.11       (142.5 projected max SC25)  

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: SIDC-SILSO.

Solar cycles 24-25

Smoothed SF and sunspot numbers

 

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.