Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 26, 2023 at 10:55 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 minor storm on March 25 due to a high speed stream from CH1136. Solar wind speed at SOHO ranged between 422 and 658 km/sec. The high latitude magnetometer at Andenes recorded unsettled to minor storm levels.

Solar flux density measured at 20h UT on 2.8 GHz was 160.3 - increasing 1.3 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 138.43). The Potsdam WDC planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.1). Three hour interval K indices: 32443222 (planetary), 23333322 (Boulder), 53333344 (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: 332) and in 10 active regions using 1K resolution (SN: 181) SDO/HMI images.

Region 13256 [S22W25] lost spots as the trailing spots merged into larger penumbrae. An M class flare is possible. C1 flares: C1.1 @ 18:53 UT
Region 13257 [S27W09] decayed slowly and quietly.
Region 13259 [S15W12] decayed slowly and quietly.
Region 13260 [N23W07] was mostly quiet and stable.
Region 13262 [S18E31] was mostly quiet and stable. C1 flares: C1.5 @ 21:16 UT
Region 13263 [N17W14] produced a few small C flares. C1 flares: C1.5 @ 00:39, C1.6 @ 00:57 UT
Region 13264 [N15E58] was quiet and stable.

Spotted regions not observed (or interpreted differently) by SWPC:
S8383 [N20E10] developed slowly as new flux emerged.
S8388 [S21E45] decayed slowly and quietly.
S8389 [N24W43] developed further and could produce C and maybe a minor M class flare. C1 flares: C1.3 @ 01:37, C1.1 @ 14:01 UT
S8391 [S12E28] decayed slowly and quietly.
S8392 [S26E15] was quiet and stable.
S8397 [N07W28] was quiet and stable.
New region S8398 [N21E33] was observed with tiny spots in an old plage area.

C2+ flares:

Magnitude Peak time (UT) Location Source Recorded by Comment

Coronal mass ejections (CMEs)

March 23-25: 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 large southern hemisphere coronal hole (CH1136) was Earth facing on March 20-22. A trans equatorial coronal hole (CH1137) began to rotate across the central meridian on March 23 and then collapsed. A recurrent trans equatorial coronal hole (CH1138) will likely become Earth facing on March 28.

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 conditions are likely on March 26 due to coronal hole effects. Quiet conditions are expected for March 27-28.

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
13256 2023.03.16
2023.03.17
18 42 23 S23W31 0300 EHO FHI beta-gamma

area: 0490

location: S22W25

S8370 2023.03.17       N25W54          
13257 2023.03.18
2023.03.18
2 20 6 S27W11 0180 HAX CAO

area: 0260

location: S27W09

13259 2023.03.18
2023.03.19
4 27 8 S22W17 0020 CRO CRI location: S15W12

SWPC location is far off

location: 0060

13258 2023.03.18 7     N18W49 0030 CAO    

spotless

location: N18W46

SWPC counts the spots of AR S8389

13260 2023.03.18
2023.03.19
2 10 5 N23W08 0170 CSO DSO area: 0220

location: N23W07

S8376 2023.03.18       S43W45            
S8377 2023.03.19       N24W27          
S8378 2023.03.20       N06W48            
S8380 2023.03.20       S29W49            
S8381 2023.03.20       S42W27            
S8383 2023.03.20   16 6 N20E10 0040   CRO  
13262 2023.03.21
2023.03.22
1 5 3 S18E31 0130 HSX HSX area: 0190

location: S18E31

S8386 2023.03.21       N19W36            
13263 2023.03.22
2023.03.24
8 39 19 N17W12 0050 CAO DAI  
S8388 2023.03.22   3 1 S21E45 0008   BXO  
S8389 2023.03.23   12 9 N24W43 0120   DAI  
13264 2023.03.23
2023.03.24
1 2 1 N16E56 0050 HSX HSX location: N15E58

area: 0110

S8391 2023.03.23   1   S12E28 0002   AXX  
S8392 2023.03.23   7   S26E15 0010   BXO  
S8393 2023.03.23       N39W14            
S8394 2023.03.24       N22W13         merged with AR 13263
S8395 2023.03.24       N12W55          
S8396 2023.03.24       S24W36          
S8397 2023.03.24   3   N07W28 0005   BXO  
S8398 2023.03.25   5   N21E33 0007   BXO    
Total spot count: 43 192 81  
Sunspot number: 123 332 181  (total spot count + 10 * number of spotted regions)
Weighted SN: 86 238 127  (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): 135 183 145  

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) 14.48
(current
SC25 peak)
2023.03 159.2 (1)   86.7 (2A) / 107.5 (2B) / 136.3 (2C) (122.0 projected, +3.1) (15.8)
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.